feat: add more built-in highres upscalers (#1456)

.github/workflows/build.yml

@@ -176,6 +176,7 @@ jobs:
 
   build-and-push-docker-images:
     name: Build and push container images
+    if: ${{ github.event_name != 'pull_request' }}
     runs-on: ubuntu-latest
 
     permissions:

CMakeLists.txt

@@ -11,6 +11,10 @@ endif()
 if (MSVC)
     add_compile_definitions(_CRT_SECURE_NO_WARNINGS)
     add_compile_definitions(_SILENCE_CXX17_CODECVT_HEADER_DEPRECATION_WARNING)
+    add_compile_options(
+        $<$<COMPILE_LANGUAGE:C>:/MP>
+        $<$<COMPILE_LANGUAGE:CXX>:/MP>
+    )
 endif()
 
 set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/bin)
@@ -152,10 +156,12 @@ endif()
 
 set(SD_LIB stable-diffusion)
 
-file(GLOB SD_LIB_SOURCES
+file(GLOB SD_LIB_SOURCES CONFIGURE_DEPENDS
     "src/*.h"
     "src/*.cpp"
     "src/*.hpp"
+    "src/model_io/*.h"
+    "src/model_io/*.cpp"
     "src/tokenizers/*.h"
     "src/tokenizers/*.cpp"
     "src/tokenizers/vocab/*.h"

README.md

@@ -77,9 +77,10 @@ API and command-line option may change frequently.***
   - OpenCL
   - SYCL
 - Supported weight formats
-  - Pytorch checkpoint (`.ckpt` or `.pth`)
+  - Pytorch checkpoint (`.ckpt` or `.pth` or `.pt`)
   - Safetensors (`.safetensors`)
   - GGUF (`.gguf`)
+- Convert mode supports converting model weights to `.gguf` or `.safetensors`
 - Supported platforms
     - Linux
     - Mac OS

examples/cli/README.md

@@ -4,26 +4,29 @@
 usage: ./bin/sd-cli  [options]
 
 CLI Options:
-  -o, --output <string>       path to write result image to. you can use printf-style %d format specifiers for image sequences (default:
-                              ./output.png) (eg. output_%03d.png). For video generation, single-file outputs support .avi, .webm, and animated .webp
-  --preview-path <string>     path to write preview image to (default: ./preview.png). Multi-frame previews support .avi, .webm, and animated .webp
-  --preview-interval <int>    interval in denoising steps between consecutive updates of the image preview file (default is 1, meaning updating at
-                              every step)
-  --output-begin-idx <int>    starting index for output image sequence, must be non-negative (default 0 if specified %d in output path, 1 otherwise)
-  --image <string>            path to the image to inspect (for metadata mode)
-  --metadata-format <string>  metadata output format, one of [text, json] (default: text)
-  --canny                     apply canny preprocessor (edge detection)
-  --convert-name              convert tensor name (for convert mode)
-  -v, --verbose               print extra info
-  --color                     colors the logging tags according to level
-  --taesd-preview-only        prevents usage of taesd for decoding the final image. (for use with --preview tae)
-  --preview-noisy             enables previewing noisy inputs of the models rather than the denoised outputs
-  --metadata-raw              include raw hex previews for unparsed metadata payloads
-  --metadata-brief            truncate long metadata text values in text output
-  --metadata-all              include structural/container entries such as IHDR, IDAT, and non-metadata JPEG segments
-  -M, --mode                  run mode, one of [img_gen, vid_gen, upscale, convert, metadata], default: img_gen
-  --preview                   preview method. must be one of the following [none, proj, tae, vae] (default is none)
-  -h, --help                  show this help message and exit
+  -o, --output <string>         path to write result image to. you can use printf-style %d format specifiers for image
+                                sequences (default: ./output.png) (eg. output_%03d.png). Single-file video outputs
+                                support .avi, .webm, and animated .webp
+  --image <string>              path to the image to inspect (for metadata mode)
+  --metadata-format <string>    metadata output format, one of [text, json] (default: text)
+  --preview-path <string>       path to write preview image to (default: ./preview.png). Multi-frame previews support
+                                .avi, .webm, and animated .webp
+  --preview-interval <int>      interval in denoising steps between consecutive updates of the image preview file
+                                (default is 1, meaning updating at every step)
+  --output-begin-idx <int>      starting index for output image sequence, must be non-negative (default 0 if specified
+                                %d in output path, 1 otherwise)
+  --canny                       apply canny preprocessor (edge detection)
+  --convert-name                convert tensor name (for convert mode)
+  -v, --verbose                 print extra info
+  --color                       colors the logging tags according to level
+  --taesd-preview-only          prevents usage of taesd for decoding the final image. (for use with --preview tae)
+  --preview-noisy               enables previewing noisy inputs of the models rather than the denoised outputs
+  --metadata-raw                include raw hex previews for unparsed metadata payloads
+  --metadata-brief              truncate long metadata text values in text output
+  --metadata-all                include structural/container entries such as IHDR, IDAT, and non-metadata JPEG segments
+  -M, --mode                    run mode, one of [img_gen, vid_gen, upscale, convert, metadata], default: img_gen
+  --preview                     preview method. must be one of the following [none, proj, tae, vae] (default is none)
+  -h, --help                    show this help message and exit
 
 Context Options:
   -m, --model <string>                     path to full model
@@ -31,7 +34,8 @@ Context Options:
   --clip_g <string>                        path to the clip-g text encoder
   --clip_vision <string>                   path to the clip-vision encoder
   --t5xxl <string>                         path to the t5xxl text encoder
-  --llm <string>                           path to the llm text encoder. For example: (qwenvl2.5 for qwen-image, mistral-small3.2 for flux2, ...)
+  --llm <string>                           path to the llm text encoder. For example: (qwenvl2.5 for qwen-image,
+                                           mistral-small3.2 for flux2, ...)
   --llm_vision <string>                    path to the llm vit
   --qwen2vl <string>                       alias of --llm. Deprecated.
   --qwen2vl_vision <string>                alias of --llm_vision. Deprecated.
@@ -43,16 +47,16 @@ Context Options:
   --control-net <string>                   path to control net model
   --embd-dir <string>                      embeddings directory
   --lora-model-dir <string>                lora model directory
+  --hires-upscalers-dir <string>           highres fix upscaler model directory
   --tensor-type-rules <string>             weight type per tensor pattern (example: "^vae\.=f16,model\.=q8_0")
   --photo-maker <string>                   path to PHOTOMAKER model
   --upscale-model <string>                 path to esrgan model.
-  -t, --threads <int>                      number of threads to use during computation (default: -1). If threads <= 0, then threads will be set to the number of
-                                           CPU physical cores
+  -t, --threads <int>                      number of threads to use during computation (default: -1). If threads <= 0,
+                                           then threads will be set to the number of CPU physical cores
   --chroma-t5-mask-pad <int>               t5 mask pad size of chroma
-  --vae-tile-overlap <float>               tile overlap for vae tiling, in fraction of tile size (default: 0.5)
-  --vae-tiling                             process vae in tiles to reduce memory usage
   --force-sdxl-vae-conv-scale              force use of conv scale on sdxl vae
-  --offload-to-cpu                         place the weights in RAM to save VRAM, and automatically load them into VRAM when needed
+  --offload-to-cpu                         place the weights in RAM to save VRAM, and automatically load them into VRAM
+                                           when needed
   --mmap                                   whether to memory-map model
   --control-net-cpu                        keep controlnet in cpu (for low vram)
   --clip-on-cpu                            keep clip in cpu (for low vram)
@@ -67,20 +71,19 @@ Context Options:
   --chroma-disable-dit-mask                disable dit mask for chroma
   --qwen-image-zero-cond-t                 enable zero_cond_t for qwen image
   --chroma-enable-t5-mask                  enable t5 mask for chroma
-  --type                                   weight type (examples: f32, f16, q4_0, q4_1, q5_0, q5_1, q8_0, q2_K, q3_K, q4_K). If not specified, the default is the
-                                           type of the weight file
+  --type                                   weight type (examples: f32, f16, q4_0, q4_1, q5_0, q5_1, q8_0, q2_K, q3_K,
+                                           q4_K). If not specified, the default is the type of the weight file
   --rng                                    RNG, one of [std_default, cuda, cpu], default: cuda(sd-webui), cpu(comfyui)
   --sampler-rng                            sampler RNG, one of [std_default, cuda, cpu]. If not specified, use --rng
-  --prediction                             prediction type override, one of [eps, v, edm_v, sd3_flow, flux_flow, flux2_flow]
-  --lora-apply-mode                        the way to apply LoRA, one of [auto, immediately, at_runtime], default is auto. In auto mode, if the model weights
-                                           contain any quantized parameters, the at_runtime mode will be used; otherwise,
-                                           immediately will be used.The immediately mode may have precision and
-                                           compatibility issues with quantized parameters, but it usually offers faster inference
-                                           speed and, in some cases, lower memory usage. The at_runtime mode, on the
-                                           other hand, is exactly the opposite.
-  --vae-tile-size                          tile size for vae tiling, format [X]x[Y] (default: 32x32)
-  --vae-relative-tile-size                 relative tile size for vae tiling, format [X]x[Y], in fraction of image size if < 1, in number of tiles per dim if >=1
-                                           (overrides --vae-tile-size)
+  --prediction                             prediction type override, one of [eps, v, edm_v, sd3_flow, flux_flow,
+                                           flux2_flow]
+  --lora-apply-mode                        the way to apply LoRA, one of [auto, immediately, at_runtime], default is
+                                           auto. In auto mode, if the model weights contain any quantized parameters,
+                                           the at_runtime mode will be used; otherwise, immediately will be used.The
+                                           immediately mode may have precision and compatibility issues with quantized
+                                           parameters, but it usually offers faster inference speed and, in some cases,
+                                           lower memory usage. The at_runtime mode, on the other hand, is exactly the
+                                           opposite.
 
 Generation Options:
   -p, --prompt <string>                    the prompt to render
@@ -89,69 +92,99 @@ Generation Options:
   --end-img <string>                       path to the end image, required by flf2v
   --mask <string>                          path to the mask image
   --control-image <string>                 path to control image, control net
-  --control-video <string>                 path to control video frames, It must be a directory path. The video frames inside should be stored as images in
-                                           lexicographical (character) order. For example, if the control video path is
-                                           `frames`, the directory contain images such as 00.png, 01.png, ... etc.
+  --control-video <string>                 path to control video frames, It must be a directory path. The video frames
+                                           inside should be stored as images in lexicographical (character) order. For
+                                           example, if the control video path is `frames`, the directory contain images
+                                           such as 00.png, 01.png, ... etc.
   --pm-id-images-dir <string>              path to PHOTOMAKER input id images dir
   --pm-id-embed-path <string>              path to PHOTOMAKER v2 id embed
+  --hires-upscaler <string>                highres fix upscaler, Lanczos, Nearest, Latent, Latent (nearest), Latent
+                                           (nearest-exact), Latent (antialiased), Latent (bicubic), Latent (bicubic
+                                           antialiased), or a model name under --hires-upscalers-dir (default: Latent)
   -H, --height <int>                       image height, in pixel space (default: 512)
   -W, --width <int>                        image width, in pixel space (default: 512)
   --steps <int>                            number of sample steps (default: 20)
   --high-noise-steps <int>                 (high noise) number of sample steps (default: -1 = auto)
-  --clip-skip <int>                        ignore last layers of CLIP network; 1 ignores none, 2 ignores one layer (default: -1). <= 0 represents unspecified,
-                                           will be 1 for SD1.x, 2 for SD2.x
+  --clip-skip <int>                        ignore last layers of CLIP network; 1 ignores none, 2 ignores one layer
+                                           (default: -1). <= 0 represents unspecified, will be 1 for SD1.x, 2 for SD2.x
   -b, --batch-count <int>                  batch count
   --video-frames <int>                     video frames (default: 1)
   --fps <int>                              fps (default: 24)
-  --timestep-shift <int>                   shift timestep for NitroFusion models (default: 0). recommended N for NitroSD-Realism around 250 and 500 for
-                                           NitroSD-Vibrant
+  --timestep-shift <int>                   shift timestep for NitroFusion models (default: 0). recommended N for
+                                           NitroSD-Realism around 250 and 500 for NitroSD-Vibrant
   --upscale-repeats <int>                  Run the ESRGAN upscaler this many times (default: 1)
   --upscale-tile-size <int>                tile size for ESRGAN upscaling (default: 128)
+  --hires-width <int>                      highres fix target width, 0 to use --hires-scale (default: 0)
+  --hires-height <int>                     highres fix target height, 0 to use --hires-scale (default: 0)
+  --hires-steps <int>                      highres fix second pass sample steps, 0 to reuse --steps (default: 0)
+  --hires-upscale-tile-size <int>          highres fix upscaler tile size, reserved for model-backed upscalers (default:
+                                           128)
   --cfg-scale <float>                      unconditional guidance scale: (default: 7.0)
-  --img-cfg-scale <float>                  image guidance scale for inpaint or instruct-pix2pix models: (default: same as --cfg-scale)
+  --img-cfg-scale <float>                  image guidance scale for inpaint or instruct-pix2pix models: (default: same
+                                           as --cfg-scale)
   --guidance <float>                       distilled guidance scale for models with guidance input (default: 3.5)
-  --slg-scale <float>                      skip layer guidance (SLG) scale, only for DiT models: (default: 0). 0 means disabled, a value of 2.5 is nice for sd3.5
-                                           medium
+  --slg-scale <float>                      skip layer guidance (SLG) scale, only for DiT models: (default: 0). 0 means
+                                           disabled, a value of 2.5 is nice for sd3.5 medium
   --skip-layer-start <float>               SLG enabling point (default: 0.01)
   --skip-layer-end <float>                 SLG disabling point (default: 0.2)
-  --eta <float>                            noise multiplier (default: 0 for ddim_trailing, tcd, res_multistep and res_2s; 1 for euler_a, er_sde and dpm++2s_a)
+  --eta <float>                            noise multiplier (default: 0 for ddim_trailing, tcd, res_multistep and
+                                           res_2s; 1 for euler_a, er_sde and dpm++2s_a)
   --flow-shift <float>                     shift value for Flow models like SD3.x or WAN (default: auto)
   --high-noise-cfg-scale <float>           (high noise) unconditional guidance scale: (default: 7.0)
-  --high-noise-img-cfg-scale <float>       (high noise) image guidance scale for inpaint or instruct-pix2pix models (default: same as --cfg-scale)
-  --high-noise-guidance <float>            (high noise) distilled guidance scale for models with guidance input (default: 3.5)
-  --high-noise-slg-scale <float>           (high noise) skip layer guidance (SLG) scale, only for DiT models: (default: 0)
+  --high-noise-img-cfg-scale <float>       (high noise) image guidance scale for inpaint or instruct-pix2pix models
+                                           (default: same as --cfg-scale)
+  --high-noise-guidance <float>            (high noise) distilled guidance scale for models with guidance input
+                                           (default: 3.5)
+  --high-noise-slg-scale <float>           (high noise) skip layer guidance (SLG) scale, only for DiT models: (default:
+                                           0)
   --high-noise-skip-layer-start <float>    (high noise) SLG enabling point (default: 0.01)
   --high-noise-skip-layer-end <float>      (high noise) SLG disabling point (default: 0.2)
-  --high-noise-eta <float>                 (high noise) noise multiplier (default: 0 for ddim_trailing, tcd, res_multistep and res_2s; 1 for euler_a, er_sde and dpm++2s_a)
+  --high-noise-eta <float>                 (high noise) noise multiplier (default: 0 for ddim_trailing, tcd,
+                                           res_multistep and res_2s; 1 for euler_a, er_sde and dpm++2s_a)
   --strength <float>                       strength for noising/unnoising (default: 0.75)
-  --pm-style-strength <float>
-  --control-strength <float>               strength to apply Control Net (default: 0.9). 1.0 corresponds to full destruction of information in init image
-  --moe-boundary <float>                   timestep boundary for Wan2.2 MoE model. (default: 0.875). Only enabled if `--high-noise-steps` is set to -1
+  --pm-style-strength <float>              
+  --control-strength <float>               strength to apply Control Net (default: 0.9). 1.0 corresponds to full
+                                           destruction of information in init image
+  --moe-boundary <float>                   timestep boundary for Wan2.2 MoE model. (default: 0.875). Only enabled if
+                                           `--high-noise-steps` is set to -1
   --vace-strength <float>                  wan vace strength
-  --increase-ref-index                     automatically increase the indices of references images based on the order they are listed (starting with 1).
+  --vae-tile-overlap <float>               tile overlap for vae tiling, in fraction of tile size (default: 0.5)
+  --hires-scale <float>                    highres fix scale when target size is not set (default: 2.0)
+  --hires-denoising-strength <float>       highres fix second pass denoising strength (default: 0.7)
+  --increase-ref-index                     automatically increase the indices of references images based on the order
+                                           they are listed (starting with 1).
   --disable-auto-resize-ref-image          disable auto resize of ref images
   --disable-image-metadata                 do not embed generation metadata on image files
+  --vae-tiling                             process vae in tiles to reduce memory usage
+  --hires                                  enable highres fix
   -s, --seed                               RNG seed (default: 42, use random seed for < 0)
-  --sampling-method                        sampling method, one of [euler, euler_a, heun, dpm2, dpm++2s_a, dpm++2m, dpm++2mv2, ipndm, ipndm_v, lcm, ddim_trailing,
-                                           tcd, res_multistep, res_2s, er_sde] (default: euler for Flux/SD3/Wan, euler_a
-                                           otherwise)
-  --high-noise-sampling-method             (high noise) sampling method, one of [euler, euler_a, heun, dpm2, dpm++2s_a, dpm++2m, dpm++2mv2, ipndm, ipndm_v, lcm,
-                                           ddim_trailing, tcd, res_multistep, res_2s, er_sde] default: euler for Flux/SD3/Wan,
-                                           euler_a otherwise
-  --scheduler                              denoiser sigma scheduler, one of [discrete, karras, exponential, ays, gits, smoothstep, sgm_uniform, simple,
-                                           kl_optimal, lcm, bong_tangent], default: discrete
-  --sigmas                                 custom sigma values for the sampler, comma-separated (e.g., "14.61,7.8,3.5,0.0").
+  --sampling-method                        sampling method, one of [euler, euler_a, heun, dpm2, dpm++2s_a, dpm++2m,
+                                           dpm++2mv2, ipndm, ipndm_v, lcm, ddim_trailing, tcd, res_multistep, res_2s,
+                                           er_sde] (default: euler for Flux/SD3/Wan, euler_a otherwise)
+  --high-noise-sampling-method             (high noise) sampling method, one of [euler, euler_a, heun, dpm2, dpm++2s_a,
+                                           dpm++2m, dpm++2mv2, ipndm, ipndm_v, lcm, ddim_trailing, tcd, res_multistep,
+                                           res_2s, er_sde] default: euler for Flux/SD3/Wan, euler_a otherwise
+  --scheduler                              denoiser sigma scheduler, one of [discrete, karras, exponential, ays, gits,
+                                           smoothstep, sgm_uniform, simple, kl_optimal, lcm, bong_tangent], default:
+                                           discrete
+  --sigmas                                 custom sigma values for the sampler, comma-separated (e.g.,
+                                           "14.61,7.8,3.5,0.0").
   --skip-layers                            layers to skip for SLG steps (default: [7,8,9])
   --high-noise-skip-layers                 (high noise) layers to skip for SLG steps (default: [7,8,9])
   -r, --ref-image                          reference image for Flux Kontext models (can be used multiple times)
-  --cache-mode                             caching method: 'easycache' (DiT), 'ucache' (UNET), 'dbcache'/'taylorseer'/'cache-dit' (DiT block-level),
-                                           'spectrum' (UNET/DiT Chebyshev+Taylor forecasting)
+  --cache-mode                             caching method: 'easycache' (DiT), 'ucache' (UNET),
+                                           'dbcache'/'taylorseer'/'cache-dit' (DiT block-level), 'spectrum' (UNET/DiT
+                                           Chebyshev+Taylor forecasting)
   --cache-option                           named cache params (key=value format, comma-separated). easycache/ucache:
-                                           threshold=,start=,end=,decay=,relative=,reset=; dbcache/taylorseer/cache-dit: Fn=,Bn=,threshold=,warmup=;
-                                           spectrum: w=,m=,lam=,window=,flex=,warmup=,stop=. Examples:
-                                           "threshold=0.25" or "threshold=1.5,reset=0" or "w=0.4,window=2"
-  --scm-mask                               SCM steps mask for cache-dit: comma-separated 0/1 (e.g., "1,1,1,0,0,1,0,0,1,0") - 1=compute, 0=can cache
+                                           threshold=,start=,end=,decay=,relative=,reset=; dbcache/taylorseer/cache-dit:
+                                           Fn=,Bn=,threshold=,warmup=; spectrum: w=,m=,lam=,window=,flex=,warmup=,stop=.
+                                           Examples: "threshold=0.25" or "threshold=1.5,reset=0"
+  --scm-mask                               SCM steps mask for cache-dit: comma-separated 0/1 (e.g.,
+                                           "1,1,1,0,0,1,0,0,1,0") - 1=compute, 0=can cache
   --scm-policy                             SCM policy: 'dynamic' (default) or 'static'
+  --vae-tile-size                          tile size for vae tiling, format [X]x[Y] (default: 32x32)
+  --vae-relative-tile-size                 relative tile size for vae tiling, format [X]x[Y], in fraction of image size
+                                           if < 1, in number of tiles per dim if >=1 (overrides --vae-tile-size)
 ```
 
 Metadata mode inspects PNG/JPEG container metadata without loading any model:

examples/cli/main.cpp

@@ -278,7 +278,9 @@ void parse_args(int argc, const char** argv, SDCliParams& cli_params, SDContextP
     bool valid = cli_params.resolve_and_validate();
     if (valid && cli_params.mode != METADATA) {
         valid = ctx_params.resolve_and_validate(cli_params.mode) &&
-                gen_params.resolve_and_validate(cli_params.mode, ctx_params.lora_model_dir);
+                gen_params.resolve_and_validate(cli_params.mode,
+                                                ctx_params.lora_model_dir,
+                                                ctx_params.hires_upscalers_dir);
     }
 
     if (!valid) {
@@ -688,6 +690,13 @@ int main(int argc, const char* argv[]) {
         vae_decode_only = false;
     }
 
+    if (gen_params.hires_enabled &&
+        (gen_params.resolved_hires_upscaler == SD_HIRES_UPSCALER_MODEL ||
+         gen_params.resolved_hires_upscaler == SD_HIRES_UPSCALER_LANCZOS ||
+         gen_params.resolved_hires_upscaler == SD_HIRES_UPSCALER_NEAREST)) {
+        vae_decode_only = false;
+    }
+
     sd_ctx_params_t sd_ctx_params = ctx_params.to_sd_ctx_params_t(vae_decode_only, true, cli_params.taesd_preview);
 
     SDImageVec results;

examples/common/common.cpp

@@ -107,47 +107,60 @@ static bool is_absolute_path(const std::string& p) {
 
 std::string ArgOptions::wrap_text(const std::string& text, size_t width, size_t indent) {
     std::ostringstream oss;
-    size_t line_len = 0;
     size_t pos      = 0;
+    size_t line_len = 0;
 
     while (pos < text.size()) {
-        // Preserve manual newlines
         if (text[pos] == '\n') {
             oss << '\n'
                 << std::string(indent, ' ');
-            line_len = indent;
+            line_len = 0;
             ++pos;
             continue;
         }
 
-        // Add the character
-        oss << text[pos];
-        ++line_len;
-        ++pos;
+        if (std::isspace(static_cast<unsigned char>(text[pos]))) {
+            ++pos;
+            continue;
+        }
 
-        // If the current line exceeds width, try to break at the last space
-        if (line_len >= width) {
-            std::string current = oss.str();
-            size_t back         = current.size();
+        size_t word_start = pos;
+        while (pos < text.size() &&
+               text[pos] != '\n' &&
+               !std::isspace(static_cast<unsigned char>(text[pos]))) {
+            ++pos;
+        }
 
-            // Find the last space (for a clean break)
-            while (back > 0 && current[back - 1] != ' ' && current[back - 1] != '\n')
-                --back;
+        std::string word = text.substr(word_start, pos - word_start);
+        while (!word.empty()) {
+            size_t separator_len = line_len == 0 ? 0 : 1;
+            if (line_len + separator_len + word.size() <= width) {
+                if (separator_len > 0) {
+                    oss << ' ';
+                    ++line_len;
+                }
+                oss << word;
+                line_len += word.size();
+                word.clear();
+                continue;
+            }
 
-            // If found a space to break on
-            if (back > 0 && current[back - 1] != '\n') {
-                std::string before = current.substr(0, back - 1);
-                std::string after  = current.substr(back);
-                oss.str("");
-                oss.clear();
-                oss << before << "\n"
-                    << std::string(indent, ' ') << after;
-            } else {
-                // If no space found, just break at width
-                oss << "\n"
+            if (line_len > 0) {
+                oss << '\n'
                     << std::string(indent, ' ');
+                line_len = 0;
+                continue;
+            }
+
+            size_t chunk_len = std::min(width, word.size());
+            oss << word.substr(0, chunk_len);
+            line_len = chunk_len;
+            word.erase(0, chunk_len);
+            if (!word.empty()) {
+                oss << '\n'
+                    << std::string(indent, ' ');
+                line_len = 0;
             }
-            line_len = indent;
         }
     }
 
@@ -351,7 +364,10 @@ ArgOptions SDContextParams::get_options() {
          "--lora-model-dir",
          "lora model directory",
          &lora_model_dir},
-
+        {"",
+         "--hires-upscalers-dir",
+         "highres fix upscaler model directory",
+         &hires_upscalers_dir},
         {"",
          "--tensor-type-rules",
          "weight type per tensor pattern (example: \"^vae\\.=f16,model\\.=q8_0\")",
@@ -649,6 +665,7 @@ std::string SDContextParams::to_string() const {
         << "  wtype: " << sd_type_name(wtype) << ",\n"
         << "  tensor_type_rules: \"" << tensor_type_rules << "\",\n"
         << "  lora_model_dir: \"" << lora_model_dir << "\",\n"
+        << "  hires_upscalers_dir: \"" << hires_upscalers_dir << "\",\n"
         << "  photo_maker_path: \"" << photo_maker_path << "\",\n"
         << "  rng_type: " << sd_rng_type_name(rng_type) << ",\n"
         << "  sampler_rng_type: " << sd_rng_type_name(sampler_rng_type) << ",\n"
@@ -777,6 +794,12 @@ ArgOptions SDGenerationParams::get_options() {
          "--pm-id-embed-path",
          "path to PHOTOMAKER v2 id embed",
          &pm_id_embed_path},
+        {"",
+         "--hires-upscaler",
+         "highres fix upscaler, Lanczos, Nearest, Latent, Latent (nearest), Latent (nearest-exact), "
+         "Latent (antialiased), Latent (bicubic), Latent (bicubic antialiased), or a model name "
+         "under --hires-upscalers-dir (default: Latent)",
+         &hires_upscaler},
     };
 
     options.int_options = {
@@ -826,6 +849,22 @@ ArgOptions SDGenerationParams::get_options() {
          "--upscale-tile-size",
          "tile size for ESRGAN upscaling (default: 128)",
          &upscale_tile_size},
+        {"",
+         "--hires-width",
+         "highres fix target width, 0 to use --hires-scale (default: 0)",
+         &hires_width},
+        {"",
+         "--hires-height",
+         "highres fix target height, 0 to use --hires-scale (default: 0)",
+         &hires_height},
+        {"",
+         "--hires-steps",
+         "highres fix second pass sample steps, 0 to reuse --steps (default: 0)",
+         &hires_steps},
+        {"",
+         "--hires-upscale-tile-size",
+         "highres fix upscaler tile size, reserved for model-backed upscalers (default: 128)",
+         &hires_upscale_tile_size},
     };
 
     options.float_options = {
@@ -913,6 +952,14 @@ ArgOptions SDGenerationParams::get_options() {
          "--vae-tile-overlap",
          "tile overlap for vae tiling, in fraction of tile size (default: 0.5)",
          &vae_tiling_params.target_overlap},
+        {"",
+         "--hires-scale",
+         "highres fix scale when target size is not set (default: 2.0)",
+         &hires_scale},
+        {"",
+         "--hires-denoising-strength",
+         "highres fix second pass denoising strength (default: 0.7)",
+         &hires_denoising_strength},
     };
 
     options.bool_options = {
@@ -936,6 +983,11 @@ ArgOptions SDGenerationParams::get_options() {
          "process vae in tiles to reduce memory usage",
          true,
          &vae_tiling_params.enabled},
+        {"",
+         "--hires",
+         "enable highres fix",
+         true,
+         &hires_enabled},
     };
 
     auto on_seed_arg = [&](int argc, const char** argv, int index) {
@@ -1424,6 +1476,37 @@ static bool parse_lora_json_field(const json& parent,
     return true;
 }
 
+static bool resolve_model_file_from_dir(const std::string& model_name,
+                                        const std::string& model_dir,
+                                        const std::vector<std::string>& valid_ext,
+                                        const char* label,
+                                        std::string& resolved_path) {
+    if (model_dir.empty()) {
+        LOG_ERROR("%s directory is empty", label);
+        return false;
+    }
+    if (model_name.empty() ||
+        model_name.find('/') != std::string::npos ||
+        model_name.find('\\') != std::string::npos ||
+        fs::path(model_name).has_root_path() ||
+        fs::path(model_name).has_extension()) {
+        LOG_ERROR("%s must be a model name without path or extension: %s", label, model_name.c_str());
+        return false;
+    }
+
+    fs::path model_dir_path = model_dir;
+    for (const auto& ext : valid_ext) {
+        fs::path try_path = model_dir_path / (model_name + ext);
+        if (fs::exists(try_path) && fs::is_regular_file(try_path)) {
+            resolved_path = try_path.lexically_normal().string();
+            return true;
+        }
+    }
+
+    LOG_ERROR("can not find %s %s in %s", label, model_name.c_str(), model_dir_path.lexically_normal().string().c_str());
+    return false;
+}
+
 bool SDGenerationParams::from_json_str(
     const std::string& json_str,
     const std::function<std::string(const std::string&)>& lora_path_resolver) {
@@ -1487,6 +1570,34 @@ bool SDGenerationParams::from_json_str(
     load_if_exists("increase_ref_index", increase_ref_index);
     load_if_exists("embed_image_metadata", embed_image_metadata);
 
+    if (j.contains("hires") && j["hires"].is_object()) {
+        const json& hires_json = j["hires"];
+        if (hires_json.contains("enabled") && hires_json["enabled"].is_boolean()) {
+            hires_enabled = hires_json["enabled"];
+        }
+        if (hires_json.contains("upscaler") && hires_json["upscaler"].is_string()) {
+            hires_upscaler = hires_json["upscaler"];
+        }
+        if (hires_json.contains("scale") && hires_json["scale"].is_number()) {
+            hires_scale = hires_json["scale"];
+        }
+        if (hires_json.contains("target_width") && hires_json["target_width"].is_number_integer()) {
+            hires_width = hires_json["target_width"];
+        }
+        if (hires_json.contains("target_height") && hires_json["target_height"].is_number_integer()) {
+            hires_height = hires_json["target_height"];
+        }
+        if (hires_json.contains("steps") && hires_json["steps"].is_number_integer()) {
+            hires_steps = hires_json["steps"];
+        }
+        if (hires_json.contains("denoising_strength") && hires_json["denoising_strength"].is_number()) {
+            hires_denoising_strength = hires_json["denoising_strength"];
+        }
+        if (hires_json.contains("upscale_tile_size") && hires_json["upscale_tile_size"].is_number_integer()) {
+            hires_upscale_tile_size = hires_json["upscale_tile_size"];
+        }
+    }
+
     auto parse_sample_params_json = [&](const json& sample_json,
                                         sd_sample_params_t& target_params,
                                         std::vector<int>& target_skip_layers,
@@ -1589,10 +1700,18 @@ bool SDGenerationParams::from_json_str(
         LOG_ERROR("invalid init_image");
         return false;
     }
+    if (!parse_image_json_field(j, "end_image", 3, width, height, end_image)) {
+        LOG_ERROR("invalid end_image");
+        return false;
+    }
     if (!parse_image_array_json_field(j, "ref_images", 3, width, height, ref_images)) {
         LOG_ERROR("invalid ref_images");
         return false;
     }
+    if (!parse_image_array_json_field(j, "control_frames", 3, width, height, control_frames)) {
+        LOG_ERROR("invalid control_frames");
+        return false;
+    }
     if (!parse_image_json_field(j, "mask_image", 1, width, height, mask_image)) {
         LOG_ERROR("invalid mask_image");
         return false;
@@ -1792,7 +1911,7 @@ bool SDGenerationParams::initialize_cache_params() {
     return true;
 }
 
-bool SDGenerationParams::resolve(const std::string& lora_model_dir, bool strict) {
+bool SDGenerationParams::resolve(const std::string& lora_model_dir, const std::string& hires_upscalers_dir, bool strict) {
     if (high_noise_sample_params.sample_steps <= 0) {
         high_noise_sample_params.sample_steps = -1;
     }
@@ -1811,6 +1930,27 @@ bool SDGenerationParams::resolve(const std::string& lora_model_dir, bool strict)
         sample_params.sample_steps = std::clamp(sample_params.sample_steps, 1, 100);
     }
 
+    hires_upscaler_model_path.clear();
+    if (hires_enabled) {
+        if (hires_upscaler.empty()) {
+            hires_upscaler = "Latent";
+        }
+        resolved_hires_upscaler = str_to_sd_hires_upscaler(hires_upscaler.c_str());
+        if (resolved_hires_upscaler == SD_HIRES_UPSCALER_NONE) {
+            hires_enabled = false;
+        } else if (resolved_hires_upscaler == SD_HIRES_UPSCALER_COUNT) {
+            static const std::vector<std::string> valid_ext = {".gguf", ".safetensors", ".pt", ".pth"};
+            if (!resolve_model_file_from_dir(hires_upscaler,
+                                             hires_upscalers_dir,
+                                             valid_ext,
+                                             "hires upscaler",
+                                             hires_upscaler_model_path)) {
+                return false;
+            }
+            resolved_hires_upscaler = SD_HIRES_UPSCALER_MODEL;
+        }
+    }
+
     prompt_with_lora = prompt;
     if (!lora_model_dir.empty()) {
         extract_and_remove_lora(lora_model_dir);
@@ -1875,6 +2015,29 @@ bool SDGenerationParams::validate(SDMode mode) {
         return false;
     }
 
+    if (hires_enabled) {
+        if (hires_width < 0 || hires_height < 0) {
+            LOG_ERROR("error: hires target width and height must be >= 0");
+            return false;
+        }
+        if (hires_scale <= 0.f && hires_width <= 0 && hires_height <= 0) {
+            LOG_ERROR("error: hires scale must be positive when target size is not set");
+            return false;
+        }
+        if (hires_steps < 0) {
+            LOG_ERROR("error: hires steps must be >= 0");
+            return false;
+        }
+        if (hires_denoising_strength <= 0.f || hires_denoising_strength > 1.f) {
+            LOG_ERROR("error: hires denoising strength must be in (0.0, 1.0]");
+            return false;
+        }
+        if (hires_upscale_tile_size < 1) {
+            LOG_ERROR("error: hires upscale tile size must be positive");
+            return false;
+        }
+    }
+
     if (mode == UPSCALE) {
         if (init_image_path.length() == 0) {
             LOG_ERROR("error: upscale mode needs an init image (--init-img)\n");
@@ -1885,8 +2048,11 @@ bool SDGenerationParams::validate(SDMode mode) {
     return true;
 }
 
-bool SDGenerationParams::resolve_and_validate(SDMode mode, const std::string& lora_model_dir, bool strict) {
-    if (!resolve(lora_model_dir, strict)) {
+bool SDGenerationParams::resolve_and_validate(SDMode mode,
+                                              const std::string& lora_model_dir,
+                                              const std::string& hires_upscalers_dir,
+                                              bool strict) {
+    if (!resolve(lora_model_dir, hires_upscalers_dir, strict)) {
         return false;
     }
     if (!validate(mode)) {
@@ -1957,6 +2123,16 @@ sd_img_gen_params_t SDGenerationParams::to_sd_img_gen_params_t() {
     params.pm_params             = pm_params;
     params.vae_tiling_params     = vae_tiling_params;
     params.cache                 = cache_params;
+
+    params.hires.enabled            = hires_enabled;
+    params.hires.upscaler           = resolved_hires_upscaler;
+    params.hires.model_path         = hires_upscaler_model_path.empty() ? nullptr : hires_upscaler_model_path.c_str();
+    params.hires.scale              = hires_scale;
+    params.hires.target_width       = hires_width;
+    params.hires.target_height      = hires_height;
+    params.hires.steps              = hires_steps;
+    params.hires.denoising_strength = hires_denoising_strength;
+    params.hires.upscale_tile_size  = hires_upscale_tile_size;
     return params;
 }
 
@@ -2081,6 +2257,15 @@ std::string SDGenerationParams::to_string() const {
         << "  seed: " << seed << ",\n"
         << "  upscale_repeats: " << upscale_repeats << ",\n"
         << "  upscale_tile_size: " << upscale_tile_size << ",\n"
+        << "  hires: { enabled: " << (hires_enabled ? "true" : "false")
+        << ", upscaler: \"" << hires_upscaler << "\""
+        << ", model_path: \"" << hires_upscaler_model_path << "\""
+        << ", scale: " << hires_scale
+        << ", target_width: " << hires_width
+        << ", target_height: " << hires_height
+        << ", steps: " << hires_steps
+        << ", denoising_strength: " << hires_denoising_strength
+        << ", upscale_tile_size: " << hires_upscale_tile_size << " },\n"
         << "  vae_tiling_params: { "
         << vae_tiling_params.enabled << ", "
         << vae_tiling_params.tile_size_x << ", "
@@ -2154,6 +2339,13 @@ std::string get_image_params(const SDContextParams& ctx_params, const SDGenerati
     if (gen_params.clip_skip != -1) {
         parameter_string += "Clip skip: " + std::to_string(gen_params.clip_skip) + ", ";
     }
+    if (gen_params.hires_enabled) {
+        parameter_string += "Hires upscale: " + gen_params.hires_upscaler + ", ";
+        parameter_string += "Hires scale: " + std::to_string(gen_params.hires_scale) + ", ";
+        parameter_string += "Hires resize: " + std::to_string(gen_params.hires_width) + "x" + std::to_string(gen_params.hires_height) + ", ";
+        parameter_string += "Hires steps: " + std::to_string(gen_params.hires_steps) + ", ";
+        parameter_string += "Denoising strength: " + std::to_string(gen_params.hires_denoising_strength) + ", ";
+    }
     parameter_string += "Version: stable-diffusion.cpp";
     return parameter_string;
 }

examples/common/common.h

@@ -101,6 +101,7 @@ struct SDContextParams {
     sd_type_t wtype = SD_TYPE_COUNT;
     std::string tensor_type_rules;
     std::string lora_model_dir = ".";
+    std::string hires_upscalers_dir;
 
     std::map<std::string, std::string> embedding_map;
     std::vector<sd_embedding_t> embedding_vec;
@@ -190,12 +191,23 @@ struct SDGenerationParams {
     int upscale_repeats   = 1;
     int upscale_tile_size = 128;
 
+    bool hires_enabled         = false;
+    std::string hires_upscaler = "Latent";
+    std::string hires_upscaler_model_path;
+    float hires_scale              = 2.f;
+    int hires_width                = 0;
+    int hires_height               = 0;
+    int hires_steps                = 0;
+    float hires_denoising_strength = 0.7f;
+    int hires_upscale_tile_size    = 128;
+
     std::map<std::string, float> lora_map;
     std::map<std::string, float> high_noise_lora_map;
 
     // Derived and normalized fields.
     std::string prompt_with_lora;  // for metadata record only
     std::vector<sd_lora_t> lora_vec;
+    sd_hires_upscaler_t resolved_hires_upscaler;
 
     // Owned execution payload.
     SDImageOwner init_image;
@@ -225,9 +237,12 @@ struct SDGenerationParams {
     void set_width_and_height_if_unset(int w, int h);
     int get_resolved_width() const;
     int get_resolved_height() const;
-    bool resolve(const std::string& lora_model_dir, bool strict = false);
+    bool resolve(const std::string& lora_model_dir, const std::string& hires_upscalers_dir, bool strict = false);
     bool validate(SDMode mode);
-    bool resolve_and_validate(SDMode mode, const std::string& lora_model_dir, bool strict = false);
+    bool resolve_and_validate(SDMode mode,
+                              const std::string& lora_model_dir,
+                              const std::string& hires_upscalers_dir,
+                              bool strict = false);
     sd_img_gen_params_t to_sd_img_gen_params_t();
     sd_vid_gen_params_t to_sd_vid_gen_params_t();
     std::string to_string() const;

examples/common/media_io.cpp

@@ -95,6 +95,57 @@ using WebPMuxPtr         = std::unique_ptr<WebPMux, WebPMuxDeleter>;
 using WebPAnimEncoderPtr = std::unique_ptr<WebPAnimEncoder, WebPAnimEncoderDeleter>;
 #endif
 
+#ifdef SD_USE_WEBM
+class MemoryMkvWriter : public mkvmuxer::IMkvWriter {
+public:
+    mkvmuxer::int32 Write(const void* buf, mkvmuxer::uint32 len) override {
+        if (buf == nullptr && len > 0) {
+            return -1;
+        }
+        const size_t end_pos = position_ + static_cast<size_t>(len);
+        if (end_pos > data_.size()) {
+            data_.resize(end_pos);
+        }
+        if (len > 0) {
+            memcpy(data_.data() + position_, buf, len);
+        }
+        position_ = end_pos;
+        return 0;
+    }
+
+    mkvmuxer::int64 Position() const override {
+        return static_cast<mkvmuxer::int64>(position_);
+    }
+
+    mkvmuxer::int32 Position(mkvmuxer::int64 position) override {
+        if (position < 0) {
+            return -1;
+        }
+        const size_t target = static_cast<size_t>(position);
+        if (target > data_.size()) {
+            data_.resize(target);
+        }
+        position_ = target;
+        return 0;
+    }
+
+    bool Seekable() const override {
+        return true;
+    }
+
+    void ElementStartNotify(mkvmuxer::uint64, mkvmuxer::int64) override {
+    }
+
+    const std::vector<uint8_t>& data() const {
+        return data_;
+    }
+
+private:
+    std::vector<uint8_t> data_;
+    size_t position_ = 0;
+};
+#endif
+
 bool read_binary_file_bytes(const char* path, std::vector<uint8_t>& data) {
     std::ifstream fin(fs::path(path), std::ios::binary);
     if (!fin) {
@@ -570,6 +621,32 @@ void write_u16_le(FILE* f, uint16_t val) {
     fwrite(&val, 2, 1, f);
 }
 
+void write_u32_le(std::vector<uint8_t>& data, uint32_t val) {
+    data.push_back(static_cast<uint8_t>(val & 0xFF));
+    data.push_back(static_cast<uint8_t>((val >> 8) & 0xFF));
+    data.push_back(static_cast<uint8_t>((val >> 16) & 0xFF));
+    data.push_back(static_cast<uint8_t>((val >> 24) & 0xFF));
+}
+
+void write_u16_le(std::vector<uint8_t>& data, uint16_t val) {
+    data.push_back(static_cast<uint8_t>(val & 0xFF));
+    data.push_back(static_cast<uint8_t>((val >> 8) & 0xFF));
+}
+
+void patch_u32_le(std::vector<uint8_t>& data, size_t offset, uint32_t val) {
+    if (offset + 4 > data.size()) {
+        return;
+    }
+    data[offset + 0] = static_cast<uint8_t>(val & 0xFF);
+    data[offset + 1] = static_cast<uint8_t>((val >> 8) & 0xFF);
+    data[offset + 2] = static_cast<uint8_t>((val >> 16) & 0xFF);
+    data[offset + 3] = static_cast<uint8_t>((val >> 24) & 0xFF);
+}
+
+void write_fourcc(std::vector<uint8_t>& data, const char* fourcc) {
+    data.insert(data.end(), fourcc, fourcc + 4);
+}
+
 EncodedImageFormat encoded_image_format_from_path(const std::string& path) {
     std::string ext = fs::path(path).extension().string();
     std::transform(ext.begin(), ext.end(), ext.begin(), ::tolower);
@@ -699,95 +776,96 @@ uint8_t* load_image_from_memory(const char* image_bytes,
     return load_image_common(true, image_bytes, len, width, height, expected_width, expected_height, expected_channel);
 }
 
-int create_mjpg_avi_from_sd_images(const char* filename, sd_image_t* images, int num_images, int fps, int quality) {
+std::vector<uint8_t> create_mjpg_avi_from_sd_images_to_vector(sd_image_t* images, int num_images, int fps, int quality) {
     if (num_images == 0) {
         fprintf(stderr, "Error: Image array is empty.\n");
-        return -1;
+        return {};
     }
 
-    FilePtr file(fopen(filename, "wb"));
-    if (!file) {
-        perror("Error opening file for writing");
-        return -1;
-    }
-    FILE* f = file.get();
-
     uint32_t width    = images[0].width;
     uint32_t height   = images[0].height;
     uint32_t channels = images[0].channel;
     if (channels != 3 && channels != 4) {
         fprintf(stderr, "Error: Unsupported channel count: %u\n", channels);
-        return -1;
+        return {};
     }
 
-    fwrite("RIFF", 4, 1, f);
-    long riff_size_pos = ftell(f);
-    write_u32_le(f, 0);
-    fwrite("AVI ", 4, 1, f);
+    // stb_image_write changes JPEG sampling behavior above quality 90.
+    // MJPG AVI playback is more compatible when we keep the encoder on the
+    // <= 90 path.
+    const int mjpg_quality = std::clamp(quality, 1, 90);
 
-    fwrite("LIST", 4, 1, f);
-    write_u32_le(f, 4 + 8 + 56 + 8 + 4 + 8 + 56 + 8 + 40);
-    fwrite("hdrl", 4, 1, f);
+    std::vector<uint8_t> avi_data;
+    avi_data.reserve(static_cast<size_t>(num_images) * 1024);
 
-    fwrite("avih", 4, 1, f);
-    write_u32_le(f, 56);
-    write_u32_le(f, 1000000 / fps);
-    write_u32_le(f, 0);
-    write_u32_le(f, 0);
-    write_u32_le(f, 0x110);
-    write_u32_le(f, num_images);
-    write_u32_le(f, 0);
-    write_u32_le(f, 1);
-    write_u32_le(f, width * height * 3);
-    write_u32_le(f, width);
-    write_u32_le(f, height);
-    write_u32_le(f, 0);
-    write_u32_le(f, 0);
-    write_u32_le(f, 0);
-    write_u32_le(f, 0);
+    write_fourcc(avi_data, "RIFF");
+    const size_t riff_size_pos = avi_data.size();
+    write_u32_le(avi_data, 0);
+    write_fourcc(avi_data, "AVI ");
 
-    fwrite("LIST", 4, 1, f);
-    write_u32_le(f, 4 + 8 + 56 + 8 + 40);
-    fwrite("strl", 4, 1, f);
+    write_fourcc(avi_data, "LIST");
+    write_u32_le(avi_data, 4 + 8 + 56 + 8 + 4 + 8 + 56 + 8 + 40);
+    write_fourcc(avi_data, "hdrl");
 
-    fwrite("strh", 4, 1, f);
-    write_u32_le(f, 56);
-    fwrite("vids", 4, 1, f);
-    fwrite("MJPG", 4, 1, f);
-    write_u32_le(f, 0);
-    write_u16_le(f, 0);
-    write_u16_le(f, 0);
-    write_u32_le(f, 0);
-    write_u32_le(f, 1);
-    write_u32_le(f, fps);
-    write_u32_le(f, 0);
-    write_u32_le(f, num_images);
-    write_u32_le(f, width * height * 3);
-    write_u32_le(f, (uint32_t)-1);
-    write_u32_le(f, 0);
-    write_u16_le(f, 0);
-    write_u16_le(f, 0);
-    write_u16_le(f, 0);
-    write_u16_le(f, 0);
+    write_fourcc(avi_data, "avih");
+    write_u32_le(avi_data, 56);
+    write_u32_le(avi_data, 1000000 / fps);
+    write_u32_le(avi_data, 0);
+    write_u32_le(avi_data, 0);
+    write_u32_le(avi_data, 0x110);
+    write_u32_le(avi_data, num_images);
+    write_u32_le(avi_data, 0);
+    write_u32_le(avi_data, 1);
+    write_u32_le(avi_data, width * height * 3);
+    write_u32_le(avi_data, width);
+    write_u32_le(avi_data, height);
+    write_u32_le(avi_data, 0);
+    write_u32_le(avi_data, 0);
+    write_u32_le(avi_data, 0);
+    write_u32_le(avi_data, 0);
 
-    fwrite("strf", 4, 1, f);
-    write_u32_le(f, 40);
-    write_u32_le(f, 40);
-    write_u32_le(f, width);
-    write_u32_le(f, height);
-    write_u16_le(f, 1);
-    write_u16_le(f, 24);
-    fwrite("MJPG", 4, 1, f);
-    write_u32_le(f, width * height * 3);
-    write_u32_le(f, 0);
-    write_u32_le(f, 0);
-    write_u32_le(f, 0);
-    write_u32_le(f, 0);
+    write_fourcc(avi_data, "LIST");
+    write_u32_le(avi_data, 4 + 8 + 56 + 8 + 40);
+    write_fourcc(avi_data, "strl");
 
-    fwrite("LIST", 4, 1, f);
-    long movi_size_pos = ftell(f);
-    write_u32_le(f, 0);
-    fwrite("movi", 4, 1, f);
+    write_fourcc(avi_data, "strh");
+    write_u32_le(avi_data, 56);
+    write_fourcc(avi_data, "vids");
+    write_fourcc(avi_data, "MJPG");
+    write_u32_le(avi_data, 0);
+    write_u16_le(avi_data, 0);
+    write_u16_le(avi_data, 0);
+    write_u32_le(avi_data, 0);
+    write_u32_le(avi_data, 1);
+    write_u32_le(avi_data, fps);
+    write_u32_le(avi_data, 0);
+    write_u32_le(avi_data, num_images);
+    write_u32_le(avi_data, width * height * 3);
+    write_u32_le(avi_data, static_cast<uint32_t>(-1));
+    write_u32_le(avi_data, 0);
+    write_u16_le(avi_data, 0);
+    write_u16_le(avi_data, 0);
+    write_u16_le(avi_data, 0);
+    write_u16_le(avi_data, 0);
+
+    write_fourcc(avi_data, "strf");
+    write_u32_le(avi_data, 40);
+    write_u32_le(avi_data, 40);
+    write_u32_le(avi_data, width);
+    write_u32_le(avi_data, height);
+    write_u16_le(avi_data, 1);
+    write_u16_le(avi_data, 24);
+    write_fourcc(avi_data, "MJPG");
+    write_u32_le(avi_data, width * height * 3);
+    write_u32_le(avi_data, 0);
+    write_u32_le(avi_data, 0);
+    write_u32_le(avi_data, 0);
+    write_u32_le(avi_data, 0);
+
+    write_fourcc(avi_data, "LIST");
+    const size_t movi_size_pos = avi_data.size();
+    write_u32_le(avi_data, 0);
+    write_fourcc(avi_data, "movi");
 
     std::vector<avi_index_entry> index(static_cast<size_t>(num_images));
     std::vector<uint8_t> jpeg_data;
@@ -801,55 +879,61 @@ int create_mjpg_avi_from_sd_images(const char* filename, sd_image_t* images, int
             buffer->insert(buffer->end(), src, src + size);
         };
 
-        if (!stbi_write_jpg_to_func(write_to_buf, &jpeg_data, images[i].width, images[i].height, channels, images[i].data, quality)) {
+        if (!stbi_write_jpg_to_func(write_to_buf, &jpeg_data, images[i].width, images[i].height, channels, images[i].data, mjpg_quality)) {
             fprintf(stderr, "Error: Failed to encode JPEG frame.\n");
-            return -1;
+            return {};
         }
 
-        fwrite("00dc", 4, 1, f);
-        write_u32_le(f, (uint32_t)jpeg_data.size());
-        index[i].offset = ftell(f) - 8;
-        index[i].size   = (uint32_t)jpeg_data.size();
-        fwrite(jpeg_data.data(), 1, jpeg_data.size(), f);
+        index[i].offset = static_cast<uint32_t>(avi_data.size());
+        write_fourcc(avi_data, "00dc");
+        write_u32_le(avi_data, static_cast<uint32_t>(jpeg_data.size()));
+        index[i].size = (uint32_t)jpeg_data.size();
+        avi_data.insert(avi_data.end(), jpeg_data.begin(), jpeg_data.end());
 
         if (jpeg_data.size() % 2) {
-            fputc(0, f);
+            avi_data.push_back(0);
         }
     }
 
-    long cur_pos   = ftell(f);
-    long movi_size = cur_pos - movi_size_pos - 4;
-    fseek(f, movi_size_pos, SEEK_SET);
-    write_u32_le(f, movi_size);
-    fseek(f, cur_pos, SEEK_SET);
+    const size_t movi_size = avi_data.size() - movi_size_pos - 4;
+    patch_u32_le(avi_data, movi_size_pos, static_cast<uint32_t>(movi_size));
 
-    fwrite("idx1", 4, 1, f);
-    write_u32_le(f, num_images * 16);
+    write_fourcc(avi_data, "idx1");
+    write_u32_le(avi_data, num_images * 16);
     for (int i = 0; i < num_images; i++) {
-        fwrite("00dc", 4, 1, f);
-        write_u32_le(f, 0x10);
-        write_u32_le(f, index[i].offset);
-        write_u32_le(f, index[i].size);
+        write_fourcc(avi_data, "00dc");
+        write_u32_le(avi_data, 0x10);
+        write_u32_le(avi_data, index[i].offset);
+        write_u32_le(avi_data, index[i].size);
     }
 
-    cur_pos        = ftell(f);
-    long file_size = cur_pos - riff_size_pos - 4;
-    fseek(f, riff_size_pos, SEEK_SET);
-    write_u32_le(f, file_size);
-    fseek(f, cur_pos, SEEK_SET);
+    const size_t file_size = avi_data.size() - riff_size_pos - 4;
+    patch_u32_le(avi_data, riff_size_pos, static_cast<uint32_t>(file_size));
 
+    return avi_data;
+}
+
+int create_mjpg_avi_from_sd_images(const char* filename, sd_image_t* images, int num_images, int fps, int quality) {
+    std::vector<uint8_t> avi_data = create_mjpg_avi_from_sd_images_to_vector(images, num_images, fps, quality);
+    if (avi_data.empty()) {
+        return -1;
+    }
+    if (!write_binary_file_bytes(filename, avi_data)) {
+        perror("Error opening file for writing");
+        return -1;
+    }
     return 0;
 }
 
 #ifdef SD_USE_WEBP
-int create_animated_webp_from_sd_images(const char* filename, sd_image_t* images, int num_images, int fps, int quality) {
+std::vector<uint8_t> create_animated_webp_from_sd_images_to_vector(sd_image_t* images, int num_images, int fps, int quality) {
     if (num_images == 0) {
         fprintf(stderr, "Error: Image array is empty.\n");
-        return -1;
+        return {};
     }
     if (fps <= 0) {
         fprintf(stderr, "Error: FPS must be positive.\n");
-        return -1;
+        return {};
     }
 
     const int width    = static_cast<int>(images[0].width);
@@ -857,14 +941,14 @@ int create_animated_webp_from_sd_images(const char* filename, sd_image_t* images
     const int channels = static_cast<int>(images[0].channel);
     if (channels != 1 && channels != 3 && channels != 4) {
         fprintf(stderr, "Error: Unsupported channel count: %d\n", channels);
-        return -1;
+        return {};
     }
 
     WebPAnimEncoderOptions anim_options;
     WebPConfig config;
     if (!WebPAnimEncoderOptionsInit(&anim_options) || !WebPConfigInit(&config)) {
         fprintf(stderr, "Error: Failed to initialize WebP animation encoder.\n");
-        return -1;
+        return {};
     }
 
     config.quality      = static_cast<float>(quality);
@@ -875,13 +959,13 @@ int create_animated_webp_from_sd_images(const char* filename, sd_image_t* images
     }
     if (!WebPValidateConfig(&config)) {
         fprintf(stderr, "Error: Invalid WebP encoder configuration.\n");
-        return -1;
+        return {};
     }
 
     WebPAnimEncoderPtr enc(WebPAnimEncoderNew(width, height, &anim_options));
     if (enc == nullptr) {
         fprintf(stderr, "Error: Could not create WebPAnimEncoder object.\n");
-        return -1;
+        return {};
     }
 
     const int frame_duration_ms = std::max(1, static_cast<int>(std::lround(1000.0 / static_cast<double>(fps))));
@@ -891,13 +975,13 @@ int create_animated_webp_from_sd_images(const char* filename, sd_image_t* images
         const sd_image_t& image = images[i];
         if (static_cast<int>(image.width) != width || static_cast<int>(image.height) != height) {
             fprintf(stderr, "Error: Frame dimensions do not match.\n");
-            return -1;
+            return {};
         }
 
         WebPPictureGuard picture;
         if (!picture.initialized) {
             fprintf(stderr, "Error: Failed to initialize WebPPicture.\n");
-            return -1;
+            return {};
         }
         picture.picture.use_argb = 1;
         picture.picture.width    = width;
@@ -921,12 +1005,12 @@ int create_animated_webp_from_sd_images(const char* filename, sd_image_t* images
 
         if (!picture_ok) {
             fprintf(stderr, "Error: Failed to import frame into WebPPicture.\n");
-            return -1;
+            return {};
         }
 
         if (!WebPAnimEncoderAdd(enc.get(), &picture.picture, timestamp_ms, &config)) {
             fprintf(stderr, "Error: Failed to add frame to animated WebP: %s\n", WebPAnimEncoderGetError(enc.get()));
-            return -1;
+            return {};
         }
 
         timestamp_ms += frame_duration_ms;
@@ -934,52 +1018,50 @@ int create_animated_webp_from_sd_images(const char* filename, sd_image_t* images
 
     if (!WebPAnimEncoderAdd(enc.get(), nullptr, timestamp_ms, nullptr)) {
         fprintf(stderr, "Error: Failed to finalize animated WebP frames: %s\n", WebPAnimEncoderGetError(enc.get()));
-        return -1;
+        return {};
     }
 
     WebPDataGuard webp_data;
     if (!WebPAnimEncoderAssemble(enc.get(), &webp_data.data)) {
         fprintf(stderr, "Error: Failed to assemble animated WebP: %s\n", WebPAnimEncoderGetError(enc.get()));
-        return -1;
+        return {};
     }
 
-    FilePtr f(fopen(filename, "wb"));
-    if (!f) {
+    return std::vector<uint8_t>(webp_data.data.bytes, webp_data.data.bytes + webp_data.data.size);
+}
+
+int create_animated_webp_from_sd_images(const char* filename, sd_image_t* images, int num_images, int fps, int quality) {
+    std::vector<uint8_t> webp_data = create_animated_webp_from_sd_images_to_vector(images, num_images, fps, quality);
+    if (webp_data.empty()) {
+        return -1;
+    }
+    if (!write_binary_file_bytes(filename, webp_data)) {
         perror("Error opening file for writing");
         return -1;
     }
-    if (webp_data.data.size > 0 && fwrite(webp_data.data.bytes, 1, webp_data.data.size, f.get()) != webp_data.data.size) {
-        fprintf(stderr, "Error: Failed to write animated WebP file.\n");
-        return -1;
-    }
-
     return 0;
 }
 #endif
 
 #ifdef SD_USE_WEBM
-int create_webm_from_sd_images(const char* filename, sd_image_t* images, int num_images, int fps, int quality) {
+std::vector<uint8_t> create_webm_from_sd_images_to_vector(sd_image_t* images, int num_images, int fps, int quality) {
     if (num_images == 0) {
         fprintf(stderr, "Error: Image array is empty.\n");
-        return -1;
+        return {};
     }
     if (fps <= 0) {
         fprintf(stderr, "Error: FPS must be positive.\n");
-        return -1;
+        return {};
     }
 
     const int width  = static_cast<int>(images[0].width);
     const int height = static_cast<int>(images[0].height);
     if (width <= 0 || height <= 0) {
         fprintf(stderr, "Error: Invalid frame dimensions.\n");
-        return -1;
+        return {};
     }
 
-    mkvmuxer::MkvWriter writer;
-    if (!writer.Open(filename)) {
-        fprintf(stderr, "Error: Could not open WebM file for writing.\n");
-        return -1;
-    }
+    MemoryMkvWriter writer;
 
     const int ret = [&]() -> int {
         mkvmuxer::Segment segment;
@@ -1045,30 +1127,63 @@ int create_webm_from_sd_images(const char* filename, sd_image_t* images, int num
         }
         return 0;
     }();
-    writer.Close();
-    return ret;
+    if (ret != 0) {
+        return {};
+    }
+    return writer.data();
+}
+
+int create_webm_from_sd_images(const char* filename, sd_image_t* images, int num_images, int fps, int quality) {
+    std::vector<uint8_t> webm_data = create_webm_from_sd_images_to_vector(images, num_images, fps, quality);
+    if (webm_data.empty()) {
+        return -1;
+    }
+    if (!write_binary_file_bytes(filename, webm_data)) {
+        perror("Error opening file for writing");
+        return -1;
+    }
+    return 0;
 }
 #endif
 
-int create_video_from_sd_images(const char* filename, sd_image_t* images, int num_images, int fps, int quality) {
-    std::string path = filename ? filename : "";
-    auto pos         = path.find_last_of('.');
-    std::string ext  = pos == std::string::npos ? "" : path.substr(pos);
-    for (char& ch : ext) {
-        ch = static_cast<char>(tolower(static_cast<unsigned char>(ch)));
+std::vector<uint8_t> create_video_from_sd_images_to_vector(const std::string& output_format,
+                                                           sd_image_t* images,
+                                                           int num_images,
+                                                           int fps,
+                                                           int quality) {
+    std::string format = output_format;
+    std::transform(format.begin(), format.end(), format.begin(),
+                   [](unsigned char c) { return static_cast<char>(tolower(c)); });
+    if (!format.empty() && format[0] == '.') {
+        format.erase(format.begin());
     }
 
 #ifdef SD_USE_WEBM
-    if (ext == ".webm") {
-        return create_webm_from_sd_images(filename, images, num_images, fps, quality);
+    if (format == "webm") {
+        return create_webm_from_sd_images_to_vector(images, num_images, fps, quality);
     }
 #endif
 
 #ifdef SD_USE_WEBP
-    if (ext == ".webp") {
-        return create_animated_webp_from_sd_images(filename, images, num_images, fps, quality);
+    if (format == "webp") {
+        return create_animated_webp_from_sd_images_to_vector(images, num_images, fps, quality);
     }
 #endif
 
-    return create_mjpg_avi_from_sd_images(filename, images, num_images, fps, quality);
+    return create_mjpg_avi_from_sd_images_to_vector(images, num_images, fps, quality);
+}
+
+int create_video_from_sd_images(const char* filename, sd_image_t* images, int num_images, int fps, int quality) {
+    std::string path                = filename ? filename : "";
+    auto pos                        = path.find_last_of('.');
+    std::string ext                 = pos == std::string::npos ? "" : path.substr(pos);
+    std::vector<uint8_t> video_data = create_video_from_sd_images_to_vector(ext, images, num_images, fps, quality);
+    if (video_data.empty()) {
+        return -1;
+    }
+    if (!write_binary_file_bytes(filename, video_data)) {
+        perror("Error opening file for writing");
+        return -1;
+    }
+    return 0;
 }

examples/common/media_io.h

@@ -58,6 +58,10 @@ int create_mjpg_avi_from_sd_images(const char* filename,
                                    int num_images,
                                    int fps,
                                    int quality = 90);
+std::vector<uint8_t> create_mjpg_avi_from_sd_images_to_vector(sd_image_t* images,
+                                                              int num_images,
+                                                              int fps,
+                                                              int quality = 90);
 
 #ifdef SD_USE_WEBP
 int create_animated_webp_from_sd_images(const char* filename,
@@ -65,6 +69,10 @@ int create_animated_webp_from_sd_images(const char* filename,
                                         int num_images,
                                         int fps,
                                         int quality = 90);
+std::vector<uint8_t> create_animated_webp_from_sd_images_to_vector(sd_image_t* images,
+                                                                   int num_images,
+                                                                   int fps,
+                                                                   int quality = 90);
 #endif
 
 #ifdef SD_USE_WEBM
@@ -73,6 +81,10 @@ int create_webm_from_sd_images(const char* filename,
                                int num_images,
                                int fps,
                                int quality = 90);
+std::vector<uint8_t> create_webm_from_sd_images_to_vector(sd_image_t* images,
+                                                          int num_images,
+                                                          int fps,
+                                                          int quality = 90);
 #endif
 
 int create_video_from_sd_images(const char* filename,
@@ -80,5 +92,10 @@ int create_video_from_sd_images(const char* filename,
                                 int num_images,
                                 int fps,
                                 int quality = 90);
+std::vector<uint8_t> create_video_from_sd_images_to_vector(const std::string& output_format,
+                                                           sd_image_t* images,
+                                                           int num_images,
+                                                           int fps,
+                                                           int quality = 90);
 
 #endif  // __MEDIA_IO_H__

examples/server/README.md

@@ -123,11 +123,11 @@ In this case, the server will load and serve the specified `index.html` file ins
 usage: ./bin/sd-server  [options]
 
 Svr Options:
-  -l, --listen-ip <string>      server listen ip (default: 127.0.0.1)        
+  -l, --listen-ip <string>      server listen ip (default: 127.0.0.1)
   --serve-html-path <string>    path to HTML file to serve at root (optional)
   --listen-port <int>           server listen port (default: 1234)
   -v, --verbose                 print extra info
-  --color                       colors the logging tags according to level   
+  --color                       colors the logging tags according to level
   -h, --help                    show this help message and exit
 
 Context Options:
@@ -136,7 +136,8 @@ Context Options:
   --clip_g <string>                        path to the clip-g text encoder
   --clip_vision <string>                   path to the clip-vision encoder
   --t5xxl <string>                         path to the t5xxl text encoder
-  --llm <string>                           path to the llm text encoder. For example: (qwenvl2.5 for qwen-image, mistral-small3.2 for flux2, ...)
+  --llm <string>                           path to the llm text encoder. For example: (qwenvl2.5 for qwen-image,
+                                           mistral-small3.2 for flux2, ...)
   --llm_vision <string>                    path to the llm vit
   --qwen2vl <string>                       alias of --llm. Deprecated.
   --qwen2vl_vision <string>                alias of --llm_vision. Deprecated.
@@ -148,16 +149,16 @@ Context Options:
   --control-net <string>                   path to control net model
   --embd-dir <string>                      embeddings directory
   --lora-model-dir <string>                lora model directory
+  --hires-upscalers-dir <string>           highres fix upscaler model directory
   --tensor-type-rules <string>             weight type per tensor pattern (example: "^vae\.=f16,model\.=q8_0")
   --photo-maker <string>                   path to PHOTOMAKER model
   --upscale-model <string>                 path to esrgan model.
-  -t, --threads <int>                      number of threads to use during computation (default: -1). If threads <= 0, then threads will be set to the number of
-                                           CPU physical cores
+  -t, --threads <int>                      number of threads to use during computation (default: -1). If threads <= 0,
+                                           then threads will be set to the number of CPU physical cores
   --chroma-t5-mask-pad <int>               t5 mask pad size of chroma
-  --vae-tile-overlap <float>               tile overlap for vae tiling, in fraction of tile size (default: 0.5)
-  --vae-tiling                             process vae in tiles to reduce memory usage
   --force-sdxl-vae-conv-scale              force use of conv scale on sdxl vae
-  --offload-to-cpu                         place the weights in RAM to save VRAM, and automatically load them into VRAM when needed
+  --offload-to-cpu                         place the weights in RAM to save VRAM, and automatically load them into VRAM
+                                           when needed
   --mmap                                   whether to memory-map model
   --control-net-cpu                        keep controlnet in cpu (for low vram)
   --clip-on-cpu                            keep clip in cpu (for low vram)
@@ -172,20 +173,19 @@ Context Options:
   --chroma-disable-dit-mask                disable dit mask for chroma
   --qwen-image-zero-cond-t                 enable zero_cond_t for qwen image
   --chroma-enable-t5-mask                  enable t5 mask for chroma
-  --type                                   weight type (examples: f32, f16, q4_0, q4_1, q5_0, q5_1, q8_0, q2_K, q3_K, q4_K). If not specified, the default is the
-                                           type of the weight file
+  --type                                   weight type (examples: f32, f16, q4_0, q4_1, q5_0, q5_1, q8_0, q2_K, q3_K,
+                                           q4_K). If not specified, the default is the type of the weight file
   --rng                                    RNG, one of [std_default, cuda, cpu], default: cuda(sd-webui), cpu(comfyui)
   --sampler-rng                            sampler RNG, one of [std_default, cuda, cpu]. If not specified, use --rng
-  --prediction                             prediction type override, one of [eps, v, edm_v, sd3_flow, flux_flow, flux2_flow]
-  --lora-apply-mode                        the way to apply LoRA, one of [auto, immediately, at_runtime], default is auto. In auto mode, if the model weights
-                                           contain any quantized parameters, the at_runtime mode will be used; otherwise,
-                                           immediately will be used.The immediately mode may have precision and
-                                           compatibility issues with quantized parameters, but it usually offers faster inference
-                                           speed and, in some cases, lower memory usage. The at_runtime mode, on the
-                                           other hand, is exactly the opposite.
-  --vae-tile-size                          tile size for vae tiling, format [X]x[Y] (default: 32x32)
-  --vae-relative-tile-size                 relative tile size for vae tiling, format [X]x[Y], in fraction of image size if < 1, in number of tiles per dim if >=1
-                                           (overrides --vae-tile-size)
+  --prediction                             prediction type override, one of [eps, v, edm_v, sd3_flow, flux_flow,
+                                           flux2_flow]
+  --lora-apply-mode                        the way to apply LoRA, one of [auto, immediately, at_runtime], default is
+                                           auto. In auto mode, if the model weights contain any quantized parameters,
+                                           the at_runtime mode will be used; otherwise, immediately will be used.The
+                                           immediately mode may have precision and compatibility issues with quantized
+                                           parameters, but it usually offers faster inference speed and, in some cases,
+                                           lower memory usage. The at_runtime mode, on the other hand, is exactly the
+                                           opposite.
 
 Default Generation Options:
   -p, --prompt <string>                    the prompt to render
@@ -194,65 +194,97 @@ Default Generation Options:
   --end-img <string>                       path to the end image, required by flf2v
   --mask <string>                          path to the mask image
   --control-image <string>                 path to control image, control net
-  --control-video <string>                 path to control video frames, It must be a directory path. The video frames inside should be stored as images in
-                                           lexicographical (character) order. For example, if the control video path is
-                                           `frames`, the directory contain images such as 00.png, 01.png, ... etc.
+  --control-video <string>                 path to control video frames, It must be a directory path. The video frames
+                                           inside should be stored as images in lexicographical (character) order. For
+                                           example, if the control video path is `frames`, the directory contain images
+                                           such as 00.png, 01.png, ... etc.
   --pm-id-images-dir <string>              path to PHOTOMAKER input id images dir
   --pm-id-embed-path <string>              path to PHOTOMAKER v2 id embed
+  --hires-upscaler <string>                highres fix upscaler, Lanczos, Nearest, Latent, Latent (nearest), Latent
+                                           (nearest-exact), Latent (antialiased), Latent (bicubic), Latent (bicubic
+                                           antialiased), or a model name under --hires-upscalers-dir (default: Latent)
   -H, --height <int>                       image height, in pixel space (default: 512)
   -W, --width <int>                        image width, in pixel space (default: 512)
   --steps <int>                            number of sample steps (default: 20)
   --high-noise-steps <int>                 (high noise) number of sample steps (default: -1 = auto)
-  --clip-skip <int>                        ignore last layers of CLIP network; 1 ignores none, 2 ignores one layer (default: -1). <= 0 represents unspecified,
-                                           will be 1 for SD1.x, 2 for SD2.x
+  --clip-skip <int>                        ignore last layers of CLIP network; 1 ignores none, 2 ignores one layer
+                                           (default: -1). <= 0 represents unspecified, will be 1 for SD1.x, 2 for SD2.x
   -b, --batch-count <int>                  batch count
   --video-frames <int>                     video frames (default: 1)
   --fps <int>                              fps (default: 24)
-  --timestep-shift <int>                   shift timestep for NitroFusion models (default: 0). recommended N for NitroSD-Realism around 250 and 500 for
-                                           NitroSD-Vibrant
+  --timestep-shift <int>                   shift timestep for NitroFusion models (default: 0). recommended N for
+                                           NitroSD-Realism around 250 and 500 for NitroSD-Vibrant
   --upscale-repeats <int>                  Run the ESRGAN upscaler this many times (default: 1)
   --upscale-tile-size <int>                tile size for ESRGAN upscaling (default: 128)
+  --hires-width <int>                      highres fix target width, 0 to use --hires-scale (default: 0)
+  --hires-height <int>                     highres fix target height, 0 to use --hires-scale (default: 0)
+  --hires-steps <int>                      highres fix second pass sample steps, 0 to reuse --steps (default: 0)
+  --hires-upscale-tile-size <int>          highres fix upscaler tile size, reserved for model-backed upscalers (default:
+                                           128)
   --cfg-scale <float>                      unconditional guidance scale: (default: 7.0)
-  --img-cfg-scale <float>                  image guidance scale for inpaint or instruct-pix2pix models: (default: same as --cfg-scale)
+  --img-cfg-scale <float>                  image guidance scale for inpaint or instruct-pix2pix models: (default: same
+                                           as --cfg-scale)
   --guidance <float>                       distilled guidance scale for models with guidance input (default: 3.5)
-  --slg-scale <float>                      skip layer guidance (SLG) scale, only for DiT models: (default: 0). 0 means disabled, a value of 2.5 is nice for sd3.5
-                                           medium
+  --slg-scale <float>                      skip layer guidance (SLG) scale, only for DiT models: (default: 0). 0 means
+                                           disabled, a value of 2.5 is nice for sd3.5 medium
   --skip-layer-start <float>               SLG enabling point (default: 0.01)
   --skip-layer-end <float>                 SLG disabling point (default: 0.2)
-  --eta <float>                            noise multiplier (default: 0 for ddim_trailing, tcd, res_multistep and res_2s; 1 for euler_a, er_sde and dpm++2s_a)
+  --eta <float>                            noise multiplier (default: 0 for ddim_trailing, tcd, res_multistep and
+                                           res_2s; 1 for euler_a, er_sde and dpm++2s_a)
   --flow-shift <float>                     shift value for Flow models like SD3.x or WAN (default: auto)
   --high-noise-cfg-scale <float>           (high noise) unconditional guidance scale: (default: 7.0)
-  --high-noise-img-cfg-scale <float>       (high noise) image guidance scale for inpaint or instruct-pix2pix models (default: same as --cfg-scale)
-  --high-noise-guidance <float>            (high noise) distilled guidance scale for models with guidance input (default: 3.5)
-  --high-noise-slg-scale <float>           (high noise) skip layer guidance (SLG) scale, only for DiT models: (default: 0)
+  --high-noise-img-cfg-scale <float>       (high noise) image guidance scale for inpaint or instruct-pix2pix models
+                                           (default: same as --cfg-scale)
+  --high-noise-guidance <float>            (high noise) distilled guidance scale for models with guidance input
+                                           (default: 3.5)
+  --high-noise-slg-scale <float>           (high noise) skip layer guidance (SLG) scale, only for DiT models: (default:
+                                           0)
   --high-noise-skip-layer-start <float>    (high noise) SLG enabling point (default: 0.01)
   --high-noise-skip-layer-end <float>      (high noise) SLG disabling point (default: 0.2)
-  --high-noise-eta <float>                 (high noise) noise multiplier (default: 0 for ddim_trailing, tcd, res_multistep and res_2s; 1 for euler_a, er_sde and dpm++2s_a)
+  --high-noise-eta <float>                 (high noise) noise multiplier (default: 0 for ddim_trailing, tcd,
+                                           res_multistep and res_2s; 1 for euler_a, er_sde and dpm++2s_a)
   --strength <float>                       strength for noising/unnoising (default: 0.75)
-  --pm-style-strength <float>
-  --control-strength <float>               strength to apply Control Net (default: 0.9). 1.0 corresponds to full destruction of information in init image
-  --moe-boundary <float>                   timestep boundary for Wan2.2 MoE model. (default: 0.875). Only enabled if `--high-noise-steps` is set to -1
+  --pm-style-strength <float>              
+  --control-strength <float>               strength to apply Control Net (default: 0.9). 1.0 corresponds to full
+                                           destruction of information in init image
+  --moe-boundary <float>                   timestep boundary for Wan2.2 MoE model. (default: 0.875). Only enabled if
+                                           `--high-noise-steps` is set to -1
   --vace-strength <float>                  wan vace strength
-  --increase-ref-index                     automatically increase the indices of references images based on the order they are listed (starting with 1).
+  --vae-tile-overlap <float>               tile overlap for vae tiling, in fraction of tile size (default: 0.5)
+  --hires-scale <float>                    highres fix scale when target size is not set (default: 2.0)
+  --hires-denoising-strength <float>       highres fix second pass denoising strength (default: 0.7)
+  --increase-ref-index                     automatically increase the indices of references images based on the order
+                                           they are listed (starting with 1).
   --disable-auto-resize-ref-image          disable auto resize of ref images
   --disable-image-metadata                 do not embed generation metadata on image files
+  --vae-tiling                             process vae in tiles to reduce memory usage
+  --hires                                  enable highres fix
   -s, --seed                               RNG seed (default: 42, use random seed for < 0)
-  --sampling-method                        sampling method, one of [euler, euler_a, heun, dpm2, dpm++2s_a, dpm++2m, dpm++2mv2, ipndm, ipndm_v, lcm, ddim_trailing,
-                                           tcd, res_multistep, res_2s, er_sde] (default: euler for Flux/SD3/Wan, euler_a
-                                           otherwise)
-  --high-noise-sampling-method             (high noise) sampling method, one of [euler, euler_a, heun, dpm2, dpm++2s_a, dpm++2m, dpm++2mv2, ipndm, ipndm_v, lcm,
-                                           ddim_trailing, tcd, res_multistep, res_2s, er_sde] default: euler for Flux/SD3/Wan,
-                                           euler_a otherwise
-  --scheduler                              denoiser sigma scheduler, one of [discrete, karras, exponential, ays, gits, smoothstep, sgm_uniform, simple,
-                                           kl_optimal, lcm, bong_tangent], default: discrete
-  --sigmas                                 custom sigma values for the sampler, comma-separated (e.g., "14.61,7.8,3.5,0.0").
+  --sampling-method                        sampling method, one of [euler, euler_a, heun, dpm2, dpm++2s_a, dpm++2m,
+                                           dpm++2mv2, ipndm, ipndm_v, lcm, ddim_trailing, tcd, res_multistep, res_2s,
+                                           er_sde] (default: euler for Flux/SD3/Wan, euler_a otherwise)
+  --high-noise-sampling-method             (high noise) sampling method, one of [euler, euler_a, heun, dpm2, dpm++2s_a,
+                                           dpm++2m, dpm++2mv2, ipndm, ipndm_v, lcm, ddim_trailing, tcd, res_multistep,
+                                           res_2s, er_sde] default: euler for Flux/SD3/Wan, euler_a otherwise
+  --scheduler                              denoiser sigma scheduler, one of [discrete, karras, exponential, ays, gits,
+                                           smoothstep, sgm_uniform, simple, kl_optimal, lcm, bong_tangent], default:
+                                           discrete
+  --sigmas                                 custom sigma values for the sampler, comma-separated (e.g.,
+                                           "14.61,7.8,3.5,0.0").
   --skip-layers                            layers to skip for SLG steps (default: [7,8,9])
   --high-noise-skip-layers                 (high noise) layers to skip for SLG steps (default: [7,8,9])
   -r, --ref-image                          reference image for Flux Kontext models (can be used multiple times)
-  --cache-mode                             caching method: 'easycache' (DiT), 'ucache' (UNET), 'dbcache'/'taylorseer'/'cache-dit' (DiT block-level), 'spectrum' (UNET/DiT Chebyshev+Taylor forecasting)
+  --cache-mode                             caching method: 'easycache' (DiT), 'ucache' (UNET),
+                                           'dbcache'/'taylorseer'/'cache-dit' (DiT block-level), 'spectrum' (UNET/DiT
+                                           Chebyshev+Taylor forecasting)
   --cache-option                           named cache params (key=value format, comma-separated). easycache/ucache:
-                                           threshold=,start=,end=,decay=,relative=,reset=; dbcache/taylorseer/cache-dit: Fn=,Bn=,threshold=,warmup=. Examples:
-                                           "threshold=0.25" or "threshold=1.5,reset=0"
-  --scm-mask                               SCM steps mask for cache-dit: comma-separated 0/1 (e.g., "1,1,1,0,0,1,0,0,1,0") - 1=compute, 0=can cache
+                                           threshold=,start=,end=,decay=,relative=,reset=; dbcache/taylorseer/cache-dit:
+                                           Fn=,Bn=,threshold=,warmup=; spectrum: w=,m=,lam=,window=,flex=,warmup=,stop=.
+                                           Examples: "threshold=0.25" or "threshold=1.5,reset=0"
+  --scm-mask                               SCM steps mask for cache-dit: comma-separated 0/1 (e.g.,
+                                           "1,1,1,0,0,1,0,0,1,0") - 1=compute, 0=can cache
   --scm-policy                             SCM policy: 'dynamic' (default) or 'static'
+  --vae-tile-size                          tile size for vae tiling, format [X]x[Y] (default: 32x32)
+  --vae-relative-tile-size                 relative tile size for vae tiling, format [X]x[Y], in fraction of image size
+                                           if < 1, in number of tiles per dim if >=1 (overrides --vae-tile-size)
 ```

examples/server/api.md

@@ -9,7 +9,7 @@ The server currently exposes three API families:
 - `sdcpp API` under `/sdcpp/v1/...`
 
 The `sdcpp API` is the native API surface.
-Its request schema is also the canonical schema for `sd_cpp_extra_args`.
+Its request schema is the same schema used by `sd_cpp_extra_args`.
 
 Global LoRA rule:
 
@@ -38,6 +38,8 @@ Current generation-related endpoints include:
 - `POST /sdapi/v1/txt2img`
 - `POST /sdapi/v1/img2img`
 - `GET /sdapi/v1/loras`
+- `GET /sdapi/v1/upscalers`
+- `GET /sdapi/v1/latent-upscale-modes`
 - `GET /sdapi/v1/samplers`
 - `GET /sdapi/v1/schedulers`
 - `GET /sdapi/v1/sd-models`
@@ -55,8 +57,6 @@ Current endpoints include:
 - `POST /sdcpp/v1/jobs/{id}/cancel`
 - `POST /sdcpp/v1/vid_gen`
 
-`POST /sdcpp/v1/vid_gen` is currently exposed but returns `501 Not Implemented`.
-
 ## `sd_cpp_extra_args`
 
 `sd_cpp_extra_args` is an extension mechanism for the compatibility APIs.
@@ -79,12 +79,12 @@ Behavior:
 - The JSON block is parsed using the same field rules as the `sdcpp API`.
 - The block is removed from the final prompt before generation.
 
-Intended use:
+Supported use:
 
 - extend `OpenAI API` requests with native `stable-diffusion.cpp` controls
 - extend `sdapi` requests with native `stable-diffusion.cpp` controls
 
-Not intended use:
+Unsupported use:
 
 - do not use `sd_cpp_extra_args` with `/sdcpp/v1/*`
 
@@ -218,6 +218,13 @@ Currently supported request fields:
 | `scheduler` | `string` | Scheduler name |
 | `lora` | `array<object>` | Structured LoRA list |
 | `extra_images` | `array<string>` | Base64 or data URL images |
+| `enable_hr` | `boolean` | Enable highres fix for `txt2img` |
+| `hr_upscaler` | `string` | `Lanczos`, `Nearest`, a latent mode such as `Latent (nearest-exact)`, or an upscaler model name from `/sdapi/v1/upscalers` |
+| `hr_scale` | `number` | Highres scale when resize target is not set |
+| `hr_resize_x` | `integer` | Highres target width, `0` to use scale |
+| `hr_resize_y` | `integer` | Highres target height, `0` to use scale |
+| `hr_steps` | `integer` | Highres second-pass sample steps, `0` to reuse `steps` |
+| `denoising_strength` | `number` | Highres denoising strength for `txt2img` |
 
 Native extension fields:
 
@@ -243,6 +250,8 @@ Currently supported request fields:
 | `inpainting_mask_invert` | `integer` or `boolean` | Treated as invert flag |
 | `denoising_strength` | `number` | Clamped to `0.0..1.0` |
 
+Highres fix fields are currently handled for `txt2img`; `img2img` uses `denoising_strength` as image-to-image strength.
+
 Native extension fields:
 
 - any `sdcpp API` fields embedded through `sd_cpp_extra_args` inside `prompt`
@@ -260,6 +269,8 @@ Response fields:
 Currently exposed:
 
 - `GET /sdapi/v1/loras`
+- `GET /sdapi/v1/upscalers`
+- `GET /sdapi/v1/latent-upscale-modes`
 - `GET /sdapi/v1/samplers`
 - `GET /sdapi/v1/schedulers`
 - `GET /sdapi/v1/sd-models`
@@ -274,6 +285,26 @@ Response fields:
 | `[].name` | `string` | Display name derived from file stem |
 | `[].path` | `string` | Relative path under the configured LoRA directory |
 
+`GET /sdapi/v1/upscalers`
+
+| Field | Type | Notes |
+| --- | --- | --- |
+| `[].name` | `string` | Built-in name or model stem |
+| `[].model_name` | `string \| null` | Model family label for model-backed upscalers |
+| `[].model_path` | `string \| null` | Absolute model path for model-backed upscalers |
+| `[].model_url` | `string \| null` | Currently always null |
+| `[].scale` | `integer` | Currently `4` |
+
+Built-in entries include `None`, `Lanczos`, and `Nearest`. Model-backed entries are scanned from the top level of `--hires-upscalers-dir`; subdirectories are not scanned.
+
+`GET /sdapi/v1/latent-upscale-modes`
+
+| Field | Type | Notes |
+| --- | --- | --- |
+| `[].name` | `string` | WebUI-compatible latent upscale mode name |
+
+Built-in latent modes include `Latent`, `Latent (nearest)`, `Latent (nearest-exact)`, `Latent (antialiased)`, `Latent (bicubic)`, and `Latent (bicubic antialiased)`.
+
 `GET /sdapi/v1/samplers`
 
 | Field | Type | Notes |
@@ -372,20 +403,26 @@ Field types:
 
 Returns frontend-friendly capability metadata.
 
-Typical contents:
+The mode-aware fields are the primary interface. The top-level compatibility fields are deprecated mirrors kept for older clients.
 
-| Field | Type |
-| --- | --- |
-| `model` | `object` |
-| `defaults` | `object` |
-| `loras` | `array<object>` |
-| `samplers` | `array<string>` |
-| `schedulers` | `array<string>` |
-| `output_formats` | `array<string>` |
-| `limits` | `object` |
-| `features` | `object` |
+Top-level fields:
 
-Nested fields currently returned:
+| Field | Type | Notes |
+| --- | --- | --- |
+| `model` | `object` | Loaded model metadata |
+| `current_mode` | `string` | The native generation mode mirrored by top-level compatibility fields |
+| `supported_modes` | `array<string>` | Supported native modes such as `img_gen` or `vid_gen` |
+| `defaults` | `object` | Deprecated compatibility mirror of `defaults_by_mode[current_mode]` |
+| `output_formats` | `array<string>` | Deprecated compatibility mirror of `output_formats_by_mode[current_mode]` |
+| `features` | `object` | Deprecated compatibility mirror of `features_by_mode[current_mode]` |
+| `defaults_by_mode` | `object` | Explicit defaults for each supported mode |
+| `output_formats_by_mode` | `object` | Explicit output formats for each supported mode |
+| `features_by_mode` | `object` | Explicit feature flags for each supported mode |
+| `samplers` | `array<string>` | Available sampling methods |
+| `schedulers` | `array<string>` | Available schedulers |
+| `loras` | `array<object>` | Available LoRA entries |
+| `upscalers` | `array<object>` | Available model-backed highres upscalers |
+| `limits` | `object` | Shared queue and size limits |
 
 `model`
 
@@ -395,50 +432,24 @@ Nested fields currently returned:
 | `model.stem` | `string` |
 | `model.path` | `string` |
 
-`defaults`
+Compatibility rules:
+
+- `defaults`, `output_formats`, and `features` are deprecated compatibility mirrors
+- those three top-level fields always mirror `current_mode`
+- `supported_modes`, `defaults_by_mode`, `output_formats_by_mode`, and `features_by_mode` are the mode-aware fields
+
+Mode-aware objects:
 
 | Field | Type |
 | --- | --- |
-| `defaults.prompt` | `string` |
-| `defaults.negative_prompt` | `string` |
-| `defaults.clip_skip` | `integer` |
-| `defaults.width` | `integer` |
-| `defaults.height` | `integer` |
-| `defaults.strength` | `number` |
-| `defaults.seed` | `integer` |
-| `defaults.batch_count` | `integer` |
-| `defaults.auto_resize_ref_image` | `boolean` |
-| `defaults.increase_ref_index` | `boolean` |
-| `defaults.control_strength` | `number` |
-| `defaults.sample_params` | `object` |
-| `defaults.sample_params.scheduler` | `string` |
-| `defaults.sample_params.sample_method` | `string` |
-| `defaults.sample_params.sample_steps` | `integer` |
-| `defaults.sample_params.eta` | `number \| null` |
-| `defaults.sample_params.shifted_timestep` | `integer` |
-| `defaults.sample_params.flow_shift` | `number \| null` |
-| `defaults.sample_params.guidance` | `object` |
-| `defaults.sample_params.guidance.txt_cfg` | `number` |
-| `defaults.sample_params.guidance.img_cfg` | `number \| null` |
-| `defaults.sample_params.guidance.distilled_guidance` | `number` |
-| `defaults.sample_params.guidance.slg` | `object` |
-| `defaults.sample_params.guidance.slg.layers` | `array<integer>` |
-| `defaults.sample_params.guidance.slg.layer_start` | `number` |
-| `defaults.sample_params.guidance.slg.layer_end` | `number` |
-| `defaults.sample_params.guidance.slg.scale` | `number` |
-| `defaults.vae_tiling_params` | `object` |
-| `defaults.vae_tiling_params.enabled` | `boolean` |
-| `defaults.vae_tiling_params.tile_size_x` | `integer` |
-| `defaults.vae_tiling_params.tile_size_y` | `integer` |
-| `defaults.vae_tiling_params.target_overlap` | `number` |
-| `defaults.vae_tiling_params.rel_size_x` | `number` |
-| `defaults.vae_tiling_params.rel_size_y` | `number` |
-| `defaults.cache_mode` | `string` |
-| `defaults.cache_option` | `string` |
-| `defaults.scm_mask` | `string` |
-| `defaults.scm_policy_dynamic` | `boolean` |
-| `defaults.output_format` | `string` |
-| `defaults.output_compression` | `integer` |
+| `defaults_by_mode.img_gen` | `object` |
+| `defaults_by_mode.vid_gen` | `object` |
+| `output_formats_by_mode.img_gen` | `array<string>` |
+| `output_formats_by_mode.vid_gen` | `array<string>` |
+| `features_by_mode.img_gen` | `object` |
+| `features_by_mode.vid_gen` | `object` |
+
+Shared nested fields:
 
 `loras`
 
@@ -447,6 +458,14 @@ Nested fields currently returned:
 | `loras[].name` | `string` |
 | `loras[].path` | `string` |
 
+`upscalers`
+
+| Field | Type | Notes |
+| --- | --- | --- |
+| `upscalers[].name` | `string` | Built-in name or model stem; use this value in `hires.upscaler` |
+
+Built-in entries include `None`, `Lanczos`, `Nearest`, `Latent`, `Latent (nearest)`, `Latent (nearest-exact)`, `Latent (antialiased)`, `Latent (bicubic)`, and `Latent (bicubic antialiased)`. Model-backed entries are scanned from the top level of `--hires-upscalers-dir`; subdirectories are not scanned.
+
 `limits`
 
 | Field | Type |
@@ -458,19 +477,110 @@ Nested fields currently returned:
 | `limits.max_batch_count` | `integer` |
 | `limits.max_queue_size` | `integer` |
 
-`features`
+Shared default fields used by both `img_gen` and `vid_gen`:
 
 | Field | Type |
 | --- | --- |
-| `features.init_image` | `boolean` |
-| `features.mask_image` | `boolean` |
-| `features.control_image` | `boolean` |
-| `features.ref_images` | `boolean` |
-| `features.lora` | `boolean` |
-| `features.vae_tiling` | `boolean` |
-| `features.cache` | `boolean` |
-| `features.cancel_queued` | `boolean` |
-| `features.cancel_generating` | `boolean` |
+| `prompt` | `string` |
+| `negative_prompt` | `string` |
+| `clip_skip` | `integer` |
+| `width` | `integer` |
+| `height` | `integer` |
+| `strength` | `number` |
+| `seed` | `integer` |
+| `sample_params` | `object` |
+| `sample_params.scheduler` | `string` |
+| `sample_params.sample_method` | `string` |
+| `sample_params.sample_steps` | `integer` |
+| `sample_params.eta` | `number \| null` |
+| `sample_params.shifted_timestep` | `integer` |
+| `sample_params.flow_shift` | `number \| null` |
+| `sample_params.guidance.txt_cfg` | `number` |
+| `sample_params.guidance.img_cfg` | `number \| null` |
+| `sample_params.guidance.distilled_guidance` | `number` |
+| `sample_params.guidance.slg.layers` | `array<integer>` |
+| `sample_params.guidance.slg.layer_start` | `number` |
+| `sample_params.guidance.slg.layer_end` | `number` |
+| `sample_params.guidance.slg.scale` | `number` |
+| `vae_tiling_params` | `object` |
+| `vae_tiling_params.enabled` | `boolean` |
+| `vae_tiling_params.tile_size_x` | `integer` |
+| `vae_tiling_params.tile_size_y` | `integer` |
+| `vae_tiling_params.target_overlap` | `number` |
+| `vae_tiling_params.rel_size_x` | `number` |
+| `vae_tiling_params.rel_size_y` | `number` |
+| `cache_mode` | `string` |
+| `cache_option` | `string` |
+| `scm_mask` | `string` |
+| `scm_policy_dynamic` | `boolean` |
+| `output_format` | `string` |
+| `output_compression` | `integer` |
+
+`img_gen`-specific default fields:
+
+| Field | Type |
+| --- | --- |
+| `batch_count` | `integer` |
+| `auto_resize_ref_image` | `boolean` |
+| `increase_ref_index` | `boolean` |
+| `control_strength` | `number` |
+| `hires` | `object` |
+| `hires.enabled` | `boolean` |
+| `hires.upscaler` | `string` |
+| `hires.scale` | `number` |
+| `hires.target_width` | `integer` |
+| `hires.target_height` | `integer` |
+| `hires.steps` | `integer` |
+| `hires.denoising_strength` | `number` |
+| `hires.upscale_tile_size` | `integer` |
+
+`vid_gen`-specific default fields:
+
+| Field | Type |
+| --- | --- |
+| `video_frames` | `integer` |
+| `fps` | `integer` |
+| `moe_boundary` | `number` |
+| `vace_strength` | `number` |
+| `high_noise_sample_params` | `object` |
+| `high_noise_sample_params.scheduler` | `string` |
+| `high_noise_sample_params.sample_method` | `string` |
+| `high_noise_sample_params.sample_steps` | `integer` |
+| `high_noise_sample_params.eta` | `number \| null` |
+| `high_noise_sample_params.shifted_timestep` | `integer` |
+| `high_noise_sample_params.flow_shift` | `number \| null` |
+| `high_noise_sample_params.guidance.txt_cfg` | `number` |
+| `high_noise_sample_params.guidance.img_cfg` | `number \| null` |
+| `high_noise_sample_params.guidance.distilled_guidance` | `number` |
+| `high_noise_sample_params.guidance.slg.layers` | `array<integer>` |
+| `high_noise_sample_params.guidance.slg.layer_start` | `number` |
+| `high_noise_sample_params.guidance.slg.layer_end` | `number` |
+| `high_noise_sample_params.guidance.slg.scale` | `number` |
+
+Fields returned in `features_by_mode.img_gen`:
+
+- `init_image`
+- `mask_image`
+- `control_image`
+- `ref_images`
+- `lora`
+- `vae_tiling`
+- `hires`
+- `cache`
+- `cancel_queued`
+- `cancel_generating`
+
+Fields returned in `features_by_mode.vid_gen`:
+
+- `init_image`
+- `end_image`
+- `control_frames`
+- `high_noise_sample_params`
+- `lora`
+- `vae_tiling`
+- `cache`
+- `cancel_queued`
+- `cancel_generating`
 
 #### `POST /sdcpp/v1/img_gen`
 
@@ -521,9 +631,7 @@ Typical status codes:
 - `409 Conflict`
 - `410 Gone`
 
-### Canonical Request Schema
-
-The `sdcpp API` request body is the canonical native schema.
+### Request Body
 
 Example:
 
@@ -569,6 +677,16 @@ Example:
   },
 
   "lora": [],
+  "hires": {
+    "enabled": false,
+    "upscaler": "Latent",
+    "scale": 2.0,
+    "target_width": 0,
+    "target_height": 0,
+    "steps": 0,
+    "denoising_strength": 0.7,
+    "upscale_tile_size": 128
+  },
 
   "vae_tiling_params": {
     "enabled": false,
@@ -612,7 +730,7 @@ Channel expectations:
 If omitted or null:
 
 - single-image fields map to an empty `sd_image_t`
-- array fields map to `nullptr + count = 0`
+- array fields map to an empty C-style array, represented as `pointer = nullptr` and `count = 0`
 
 ### Field Mapping Summary
 
@@ -673,12 +791,23 @@ Other native fields:
 
 | Field | Type |
 | --- | --- |
+| `hires` | `object` |
+| `hires.enabled` | `boolean` |
+| `hires.upscaler` | `string` |
+| `hires.scale` | `number` |
+| `hires.target_width` | `integer` |
+| `hires.target_height` | `integer` |
+| `hires.steps` | `integer` |
+| `hires.denoising_strength` | `number` |
+| `hires.upscale_tile_size` | `integer` |
 | `vae_tiling_params` | `object` |
 | `cache_mode` | `string` |
 | `cache_option` | `string` |
 | `scm_mask` | `string` |
 | `scm_policy_dynamic` | `boolean` |
 
+For `hires.upscaler`, use `Lanczos`, `Nearest`, `Latent`, `Latent (nearest)`, `Latent (nearest-exact)`, `Latent (antialiased)`, `Latent (bicubic)`, `Latent (bicubic antialiased)`, or an `upscalers[].name` value from `GET /sdcpp/v1/capabilities`. Model-backed upscalers are resolved as `--hires-upscalers-dir / (name + ext)` and must live directly in that directory.
+
 HTTP-only output fields:
 
 | Field | Type |
@@ -686,11 +815,11 @@ HTTP-only output fields:
 | `output_format` | `string` |
 | `output_compression` | `integer` |
 
-### Optional Field Semantics
+### Optional Field Handling
 
-Clients should preserve unset semantics for optional sampling fields.
+Optional sampling fields may be omitted.
 
-If a user has not explicitly provided one of these fields, the client should omit it instead of injecting a guessed fallback:
+When omitted, backend defaults apply to these fields:
 
 - `sample_params.scheduler`
 - `sample_params.sample_method`
@@ -766,29 +895,394 @@ Example cancelled job:
 }
 ```
 
-### Validation and Retention
+### Submission Errors
 
-Recommended behavior:
+`POST /sdcpp/v1/img_gen` may return:
 
-- malformed JSON returns `400`
-- invalid image payloads return `400`
-- invalid parameter structure returns `400`
-- queue full returns `429` or `503`
-- accepted runtime failures transition the job to `failed`
-- unsupported in-progress cancellation may return `409`
+- `202 Accepted` when the job is created
+- `400 Bad Request` for an empty body, unsupported model mode, invalid JSON, or invalid generation parameters
+- `429 Too Many Requests` when the job queue is full
+- `500 Internal Server Error` for unexpected server exceptions during submission
 
-Recommended retention controls:
+### `vid_gen`
 
-- pending job limit
-- completed job TTL
-- failed job TTL
+The following section documents the native async contract for video generation.
 
-### Future `vid_gen`
+#### `POST /sdcpp/v1/vid_gen`
 
-Future `vid_gen` should reuse the same async job model:
+Submits an async video generation job.
 
-- `POST /sdcpp/v1/vid_gen`
-- `GET /sdcpp/v1/jobs/{id}`
-- `POST /sdcpp/v1/jobs/{id}/cancel`
+Successful submission returns `202 Accepted`.
 
-Its request body should mirror `sd_vid_gen_params_t` in the same way that `img_gen` mirrors `sd_img_gen_params_t`.
+Example response:
+
+```json
+{
+  "id": "job_01HTXYZVID",
+  "kind": "vid_gen",
+  "status": "queued",
+  "created": 1775401200,
+  "poll_url": "/sdcpp/v1/jobs/job_01HTXYZVID"
+}
+```
+
+Response fields:
+
+| Field | Type |
+| --- | --- |
+| `id` | `string` |
+| `kind` | `string` |
+| `status` | `string` |
+| `created` | `integer` |
+| `poll_url` | `string` |
+
+### Request Body
+
+Compared with `img_gen`, the `vid_gen` request body:
+
+- `vid_gen` is a single video sequence job, so `batch_count` is not part of the request schema
+- `ref_images`, `mask_image`, `control_image`, `control_strength`, and `embed_image_metadata` are not part of the request schema
+- `vid_gen` adds `end_image`, `control_frames`, `high_noise_sample_params`, `video_frames`, `fps`, `moe_boundary`, and `vace_strength`
+
+Example:
+
+```json
+{
+  "prompt": "a cat walking through a rainy alley",
+  "negative_prompt": "",
+  "clip_skip": -1,
+  "width": 832,
+  "height": 480,
+  "strength": 0.75,
+  "seed": -1,
+  "video_frames": 33,
+  "fps": 16,
+  "moe_boundary": 0.875,
+  "vace_strength": 1.0,
+
+  "init_image": null,
+  "end_image": null,
+  "control_frames": [],
+
+  "sample_params": {
+    "scheduler": "discrete",
+    "sample_method": "euler",
+    "sample_steps": 28,
+    "eta": 1.0,
+    "shifted_timestep": 0,
+    "custom_sigmas": [],
+    "flow_shift": 0.0,
+    "guidance": {
+      "txt_cfg": 7.0,
+      "img_cfg": 7.0,
+      "distilled_guidance": 3.5,
+      "slg": {
+        "layers": [7, 8, 9],
+        "layer_start": 0.01,
+        "layer_end": 0.2,
+        "scale": 0.0
+      }
+    }
+  },
+
+  "high_noise_sample_params": {
+    "scheduler": "discrete",
+    "sample_method": "euler",
+    "sample_steps": -1,
+    "eta": 1.0,
+    "shifted_timestep": 0,
+    "flow_shift": 0.0,
+    "guidance": {
+      "txt_cfg": 7.0,
+      "img_cfg": 7.0,
+      "distilled_guidance": 3.5,
+      "slg": {
+        "layers": [7, 8, 9],
+        "layer_start": 0.01,
+        "layer_end": 0.2,
+        "scale": 0.0
+      }
+    }
+  },
+
+  "lora": [],
+
+  "vae_tiling_params": {
+    "enabled": false,
+    "tile_size_x": 0,
+    "tile_size_y": 0,
+    "target_overlap": 0.5,
+    "rel_size_x": 0.0,
+    "rel_size_y": 0.0
+  },
+
+  "cache_mode": "disabled",
+  "cache_option": "",
+  "scm_mask": "",
+  "scm_policy_dynamic": true,
+
+  "output_format": "webm",
+  "output_compression": 100
+}
+```
+
+### LoRA Rules
+
+- The server only accepts explicit LoRA entries from the `lora` field.
+- Prompt-embedded `<lora:...>` tags are intentionally unsupported.
+- `lora[].is_high_noise` controls whether a LoRA applies only to the high-noise stage.
+
+### Image and Frame Encoding Rules
+
+Any image field accepts:
+
+- a raw base64 string, or
+- a data URL such as `data:image/png;base64,...`
+
+Channel expectations:
+
+- `init_image`: 3 channels
+- `end_image`: 3 channels
+- `control_frames[]`: 3 channels
+
+Frame ordering rules:
+
+- `control_frames[]` order is the conditioning frame order
+- `control_frames[]` is preserved in request order
+
+If omitted or null:
+
+- single-image fields map to an empty `sd_image_t`
+- array fields map to an empty C-style array, represented as `pointer = nullptr` and `count = 0`
+
+### Field Mapping Summary
+
+Top-level scalar fields:
+
+| Field | Type |
+| --- | --- |
+| `prompt` | `string` |
+| `negative_prompt` | `string` |
+| `clip_skip` | `integer` |
+| `width` | `integer` |
+| `height` | `integer` |
+| `strength` | `number` |
+| `seed` | `integer` |
+| `video_frames` | `integer` |
+| `fps` | `integer` |
+| `moe_boundary` | `number` |
+| `vace_strength` | `number` |
+
+Image and frame fields:
+
+| Field | Type |
+| --- | --- |
+| `init_image` | `string \| null` |
+| `end_image` | `string \| null` |
+| `control_frames` | `array<string>` |
+
+LoRA fields:
+
+| Field | Type |
+| --- | --- |
+| `lora[].path` | `string` |
+| `lora[].multiplier` | `number` |
+| `lora[].is_high_noise` | `boolean` |
+
+Sampling fields:
+
+| Field | Type |
+| --- | --- |
+| `sample_params.scheduler` | `string` |
+| `sample_params.sample_method` | `string` |
+| `sample_params.sample_steps` | `integer` |
+| `sample_params.eta` | `number` |
+| `sample_params.shifted_timestep` | `integer` |
+| `sample_params.custom_sigmas` | `array<number>` |
+| `sample_params.flow_shift` | `number` |
+| `sample_params.guidance.txt_cfg` | `number` |
+| `sample_params.guidance.img_cfg` | `number` |
+| `sample_params.guidance.distilled_guidance` | `number` |
+| `sample_params.guidance.slg.layers` | `array<integer>` |
+| `sample_params.guidance.slg.layer_start` | `number` |
+| `sample_params.guidance.slg.layer_end` | `number` |
+| `sample_params.guidance.slg.scale` | `number` |
+
+High-noise sampling fields:
+
+| Field | Type |
+| --- | --- |
+| `high_noise_sample_params.scheduler` | `string` |
+| `high_noise_sample_params.sample_method` | `string` |
+| `high_noise_sample_params.sample_steps` | `integer` |
+| `high_noise_sample_params.eta` | `number` |
+| `high_noise_sample_params.shifted_timestep` | `integer` |
+| `high_noise_sample_params.flow_shift` | `number` |
+| `high_noise_sample_params.guidance.txt_cfg` | `number` |
+| `high_noise_sample_params.guidance.img_cfg` | `number` |
+| `high_noise_sample_params.guidance.distilled_guidance` | `number` |
+| `high_noise_sample_params.guidance.slg.layers` | `array<integer>` |
+| `high_noise_sample_params.guidance.slg.layer_start` | `number` |
+| `high_noise_sample_params.guidance.slg.layer_end` | `number` |
+| `high_noise_sample_params.guidance.slg.scale` | `number` |
+
+Other native fields:
+
+| Field | Type |
+| --- | --- |
+| `vae_tiling_params` | `object` |
+| `cache_mode` | `string` |
+| `cache_option` | `string` |
+| `scm_mask` | `string` |
+| `scm_policy_dynamic` | `boolean` |
+
+HTTP-only output fields:
+
+| Field | Type |
+| --- | --- |
+| `output_format` | `string` |
+| `output_compression` | `integer` |
+
+For `vid_gen`, `output_format` and `output_compression` control container encoding.
+`fps` is request metadata for the generated sequence and is echoed in the completed job result.
+
+Allowed `output_format` values:
+
+- `webm`
+- `webp`
+- `avi`
+
+Output format behavior:
+
+- `output_format` defaults to `webm`
+- `webp` means animated WebP
+- `avi` means MJPG AVI
+- `webm` requires the server to be built with WebM support; otherwise the request returns `400`
+
+### Result Payload
+
+Completed jobs return one encoded container payload, not a list of per-frame images.
+
+Result fields:
+
+- `result.b64_json` contains the whole encoded container file as base64
+- `result.mime_type` identifies the media type
+- `result.output_format` echoes the selected container format
+- `result.fps` echoes the effective playback FPS
+- `result.frame_count` reports the actual decoded frame count used to build the container
+
+Expected MIME types:
+
+| `output_format` | `mime_type` |
+| --- | --- |
+| `webm` | `video/webm` |
+| `webp` | `image/webp` |
+| `avi` | `video/x-msvideo` |
+
+### Optional Field Handling
+
+Optional sampling fields may be omitted.
+
+When omitted, backend defaults apply to these fields:
+
+- `sample_params.scheduler`
+- `sample_params.sample_method`
+- `sample_params.eta`
+- `sample_params.flow_shift`
+- `sample_params.guidance.img_cfg`
+- `high_noise_sample_params.scheduler`
+- `high_noise_sample_params.sample_method`
+- `high_noise_sample_params.eta`
+- `high_noise_sample_params.flow_shift`
+- `high_noise_sample_params.guidance.img_cfg`
+
+`high_noise_sample_params` may also be omitted entirely.
+
+### Frame Count Semantics
+
+`video_frames` is the requested target length, but the current core video path internally normalizes the effective frame count to the largest `4n + 1` value that does not exceed the requested count.
+
+Examples:
+
+- `video_frames = 33` stays `33`
+- `video_frames = 34` becomes `33`
+- `video_frames = 32` becomes `29`
+
+The completed job payload includes the actual decoded `frame_count`.
+
+### Completion Result
+
+Example completed job:
+
+```json
+{
+  "id": "job_01HTXYZVID",
+  "kind": "vid_gen",
+  "status": "completed",
+  "created": 1775401200,
+  "started": 1775401203,
+  "completed": 1775401215,
+  "queue_position": 0,
+  "result": {
+    "output_format": "webm",
+    "mime_type": "video/webm",
+    "fps": 16,
+    "frame_count": 33,
+    "b64_json": "GkXfo59ChoEBQveBAULygQRC84EIQo..."
+  },
+  "error": null
+}
+```
+
+The response returns the encoded `.webm`, animated `.webp`, or `.avi` container payload directly.
+
+### Failure Result
+
+Example failed job:
+
+```json
+{
+  "id": "job_01HTXYZVID",
+  "kind": "vid_gen",
+  "status": "failed",
+  "created": 1775401200,
+  "started": 1775401203,
+  "completed": 1775401204,
+  "queue_position": 0,
+  "result": null,
+  "error": {
+    "code": "generation_failed",
+    "message": "generate_video returned no results"
+  }
+}
+```
+
+### Cancelled Result
+
+Example cancelled job:
+
+```json
+{
+  "id": "job_01HTXYZVID",
+  "kind": "vid_gen",
+  "status": "cancelled",
+  "created": 1775401200,
+  "started": null,
+  "completed": 1775401202,
+  "queue_position": 0,
+  "result": null,
+  "error": {
+    "code": "cancelled",
+    "message": "job cancelled by client"
+  }
+}
+```
+
+### Submission Errors
+
+`POST /sdcpp/v1/vid_gen` may return:
+
+- `202 Accepted` when the job is created
+- `400 Bad Request` for an empty body, unsupported model mode, invalid JSON, invalid generation parameters, or an unsupported output format
+- `429 Too Many Requests` when the job queue is full
+- `500 Internal Server Error` for unexpected server exceptions during submission

examples/server/async_jobs.cpp

@@ -95,8 +95,12 @@ bool cancel_queued_job(AsyncJobManager& manager, AsyncGenerationJob& job) {
     job.status       = AsyncJobStatus::Cancelled;
     job.completed_at = unix_timestamp_now();
     job.result_images_b64.clear();
-    job.error_code    = "cancelled";
-    job.error_message = "job cancelled by client";
+    job.result_media_b64.clear();
+    job.result_media_mime_type.clear();
+    job.result_frame_count = 0;
+    job.result_fps         = 0;
+    job.error_code         = "cancelled";
+    job.error_message      = "job cancelled by client";
     return true;
 }
 
@@ -122,14 +126,24 @@ json make_async_job_json(const AsyncJobManager& manager, const AsyncGenerationJo
     }
 
     if (job.status == AsyncJobStatus::Completed) {
-        json images = json::array();
-        for (size_t i = 0; i < job.result_images_b64.size(); ++i) {
-            images.push_back({{"index", i}, {"b64_json", job.result_images_b64[i]}});
+        if (job.kind == AsyncJobKind::VidGen) {
+            result["result"] = {
+                {"output_format", job.vid_gen.output_format},
+                {"mime_type", job.result_media_mime_type},
+                {"fps", job.result_fps},
+                {"frame_count", job.result_frame_count},
+                {"b64_json", job.result_media_b64},
+            };
+        } else {
+            json images = json::array();
+            for (size_t i = 0; i < job.result_images_b64.size(); ++i) {
+                images.push_back({{"index", i}, {"b64_json", job.result_images_b64[i]}});
+            }
+            result["result"] = {
+                {"output_format", job.img_gen.output_format},
+                {"images", images},
+            };
         }
-        result["result"] = {
-            {"output_format", job.img_gen.output_format},
-            {"images", images},
-        };
         result["error"] = nullptr;
     } else if (job.status == AsyncJobStatus::Failed ||
                job.status == AsyncJobStatus::Cancelled) {
@@ -156,16 +170,15 @@ bool execute_img_gen_job(ServerRuntime& runtime,
     sd_img_gen_params_t params = job.img_gen.to_sd_img_gen_params_t();
 
     SDImageVec results;
-    int num_results = 0;
 
     {
         std::lock_guard<std::mutex> lock(*runtime.sd_ctx_mutex);
         sd_image_t* raw_results = generate_image(runtime.sd_ctx, &params);
-        num_results             = params.batch_count;
-        results.adopt(raw_results, num_results);
+        results.adopt(raw_results, params.batch_count);
     }
 
-    if (results.empty() || num_results <= 0) {
+    const int num_results = results.count();
+    if (num_results <= 0) {
         error_message = "generate_image returned no results";
         return false;
     }
@@ -208,6 +221,47 @@ bool execute_img_gen_job(ServerRuntime& runtime,
     return true;
 }
 
+bool execute_vid_gen_job(ServerRuntime& runtime,
+                         AsyncGenerationJob& job,
+                         std::string& output_media_b64,
+                         std::string& output_media_mime_type,
+                         int& output_frame_count,
+                         int& output_fps,
+                         std::string& error_message) {
+    sd_vid_gen_params_t params = job.vid_gen.to_sd_vid_gen_params_t();
+
+    SDImageVec results;
+    int num_results = 0;
+
+    {
+        std::lock_guard<std::mutex> lock(*runtime.sd_ctx_mutex);
+        sd_image_t* raw_results = generate_video(runtime.sd_ctx, &params, &num_results);
+        results.adopt(raw_results, num_results);
+    }
+
+    num_results = results.count();
+    if (num_results <= 0) {
+        error_message = "generate_video returned no results";
+        return false;
+    }
+
+    std::vector<uint8_t> video_bytes = create_video_from_sd_images_to_vector(job.vid_gen.output_format,
+                                                                             results.data(),
+                                                                             num_results,
+                                                                             job.vid_gen.gen_params.fps,
+                                                                             job.vid_gen.output_compression);
+    if (video_bytes.empty()) {
+        error_message = "failed to encode generated video container";
+        return false;
+    }
+
+    output_media_b64       = base64_encode(video_bytes);
+    output_media_mime_type = video_mime_type(job.vid_gen.output_format);
+    output_frame_count     = num_results;
+    output_fps             = job.vid_gen.gen_params.fps;
+    return true;
+}
+
 void async_job_worker(ServerRuntime& runtime) {
     AsyncJobManager& manager = *runtime.async_job_manager;
 
@@ -240,11 +294,23 @@ void async_job_worker(ServerRuntime& runtime) {
         }
 
         std::vector<std::string> output_images;
+        std::string output_media_b64;
+        std::string output_media_mime_type;
+        int output_frame_count = 0;
+        int output_fps         = 0;
         std::string error_message;
         bool ok = false;
 
         if (job->kind == AsyncJobKind::ImgGen) {
             ok = execute_img_gen_job(runtime, *job, output_images, error_message);
+        } else if (job->kind == AsyncJobKind::VidGen) {
+            ok = execute_vid_gen_job(runtime,
+                                     *job,
+                                     output_media_b64,
+                                     output_media_mime_type,
+                                     output_frame_count,
+                                     output_fps,
+                                     error_message);
         } else {
             error_message = "unsupported job kind";
         }
@@ -258,8 +324,12 @@ void async_job_worker(ServerRuntime& runtime) {
 
             job->completed_at = unix_timestamp_now();
             if (ok) {
-                job->status            = AsyncJobStatus::Completed;
-                job->result_images_b64 = std::move(output_images);
+                job->status                 = AsyncJobStatus::Completed;
+                job->result_images_b64      = std::move(output_images);
+                job->result_media_b64       = std::move(output_media_b64);
+                job->result_media_mime_type = std::move(output_media_mime_type);
+                job->result_frame_count     = output_frame_count;
+                job->result_fps             = output_fps;
                 job->error_code.clear();
                 job->error_message.clear();
             } else {
@@ -267,6 +337,10 @@ void async_job_worker(ServerRuntime& runtime) {
                 job->error_code    = "generation_failed";
                 job->error_message = error_message.empty() ? "unknown generation error" : error_message;
                 job->result_images_b64.clear();
+                job->result_media_b64.clear();
+                job->result_media_mime_type.clear();
+                job->result_frame_count = 0;
+                job->result_fps         = 0;
             }
 
             purge_expired_jobs(manager);

examples/server/async_jobs.h

@@ -36,7 +36,12 @@ struct AsyncGenerationJob {
     int64_t started_at    = 0;
     int64_t completed_at  = 0;
     ImgGenJobRequest img_gen;
+    VidGenJobRequest vid_gen;
     std::vector<std::string> result_images_b64;
+    std::string result_media_b64;
+    std::string result_media_mime_type;
+    int result_frame_count = 0;
+    int result_fps         = 0;
     std::string error_code;
     std::string error_message;
 };
@@ -63,4 +68,11 @@ bool execute_img_gen_job(ServerRuntime& runtime,
                          AsyncGenerationJob& job,
                          std::vector<std::string>& output_images,
                          std::string& error_message);
+bool execute_vid_gen_job(ServerRuntime& runtime,
+                         AsyncGenerationJob& job,
+                         std::string& output_media_b64,
+                         std::string& output_media_mime_type,
+                         int& output_frame_count,
+                         int& output_fps,
+                         std::string& error_message);
 void async_job_worker(ServerRuntime& runtime);

examples/server/main.cpp

@@ -48,7 +48,9 @@ static void parse_args(int argc,
 
     if (!svr_params.resolve_and_validate() ||
         !ctx_params.resolve_and_validate(IMG_GEN) ||
-        !default_gen_params.resolve_and_validate(IMG_GEN, ctx_params.lora_model_dir)) {
+        !default_gen_params.resolve_and_validate(IMG_GEN,
+                                                 ctx_params.lora_model_dir,
+                                                 ctx_params.hires_upscalers_dir)) {
         print_usage(argv[0], options_vec);
         exit(1);
     }
@@ -95,6 +97,8 @@ int main(int argc, const char** argv) {
 
     std::vector<LoraEntry> lora_cache;
     std::mutex lora_mutex;
+    std::vector<UpscalerEntry> upscaler_cache;
+    std::mutex upscaler_mutex;
     AsyncJobManager async_job_manager;
     ServerRuntime runtime = {
         sd_ctx.get(),
@@ -104,6 +108,8 @@ int main(int argc, const char** argv) {
         &default_gen_params,
         &lora_cache,
         &lora_mutex,
+        &upscaler_cache,
+        &upscaler_mutex,
         &async_job_manager,
     };
 

examples/server/routes_openai.cpp

@@ -70,7 +70,7 @@ static bool build_openai_generation_request(const httplib::Request& req,
     }
 
     // Intentionally disable prompt-embedded LoRA tag parsing for server APIs.
-    if (!request.gen_params.resolve_and_validate(IMG_GEN, "", true)) {
+    if (!request.gen_params.resolve_and_validate(IMG_GEN, "", runtime.ctx_params->hires_upscalers_dir, true)) {
         error_message = "invalid params";
         return false;
     }
@@ -212,7 +212,7 @@ static bool build_openai_edit_request(const httplib::Request& req,
     }
 
     // Intentionally disable prompt-embedded LoRA tag parsing for server APIs.
-    if (!request.gen_params.resolve_and_validate(IMG_GEN, "", true)) {
+    if (!request.gen_params.resolve_and_validate(IMG_GEN, "", runtime.ctx_params->hires_upscalers_dir, true)) {
         error_message = "invalid params";
         return false;
     }
@@ -253,6 +253,12 @@ void register_openai_api_endpoints(httplib::Server& svr, ServerRuntime& rt) {
 
     svr.Post("/v1/images/generations", [runtime](const httplib::Request& req, httplib::Response& res) {
         try {
+            if (!runtime_supports_generation_mode(*runtime, IMG_GEN)) {
+                res.status = 400;
+                res.set_content(json({{"error", unsupported_generation_mode_error(IMG_GEN)}}).dump(), "application/json");
+                return;
+            }
+
             ImgGenJobRequest request;
             std::string error_message;
             if (!build_openai_generation_request(req, *runtime, request, error_message)) {
@@ -319,6 +325,12 @@ void register_openai_api_endpoints(httplib::Server& svr, ServerRuntime& rt) {
 
     svr.Post("/v1/images/edits", [runtime](const httplib::Request& req, httplib::Response& res) {
         try {
+            if (!runtime_supports_generation_mode(*runtime, IMG_GEN)) {
+                res.status = 400;
+                res.set_content(json({{"error", unsupported_generation_mode_error(IMG_GEN)}}).dump(), "application/json");
+                return;
+            }
+
             ImgGenJobRequest request;
             std::string error_message;
             if (!build_openai_edit_request(req, *runtime, request, error_message)) {

examples/server/routes_sdapi.cpp

@@ -1,6 +1,7 @@
 #include "routes.h"
 
 #include <algorithm>
+#include <cctype>
 #include <cstring>
 #include <regex>
 #include <string_view>
@@ -35,14 +36,20 @@ static fs::path resolve_display_model_path(const ServerRuntime& runtime) {
     return {};
 }
 
+static std::string lower_ascii(std::string value) {
+    std::transform(value.begin(), value.end(), value.begin(), [](unsigned char c) {
+        return static_cast<char>(std::tolower(c));
+    });
+    return value;
+}
+
 static enum sample_method_t get_sdapi_sample_method(std::string name) {
     enum sample_method_t result = str_to_sample_method(name.c_str());
     if (result != SAMPLE_METHOD_COUNT) {
         return result;
     }
 
-    std::transform(name.begin(), name.end(), name.begin(),
-                   [](unsigned char c) { return static_cast<char>(std::tolower(c)); });
+    name = lower_ascii(name);
     static const std::unordered_map<std::string_view, sample_method_t> hardcoded{
         {"euler a", EULER_A_SAMPLE_METHOD},
         {"k_euler_a", EULER_A_SAMPLE_METHOD},
@@ -114,6 +121,18 @@ static bool build_sdapi_img_gen_request(const json& j,
     request.gen_params.width                          = j.value("width", -1);
     request.gen_params.height                         = j.value("height", -1);
 
+    if (!img2img && j.value("enable_hr", false)) {
+        request.gen_params.hires_enabled = true;
+        request.gen_params.hires_scale   = j.value("hr_scale", request.gen_params.hires_scale);
+        request.gen_params.hires_width   = j.value("hr_resize_x", request.gen_params.hires_width);
+        request.gen_params.hires_height  = j.value("hr_resize_y", request.gen_params.hires_height);
+        request.gen_params.hires_steps   = j.value("hr_steps", request.gen_params.hires_steps);
+        request.gen_params.hires_denoising_strength =
+            j.value("denoising_strength", request.gen_params.hires_denoising_strength);
+
+        request.gen_params.hires_upscaler = j.value("hr_upscaler", request.gen_params.hires_upscaler);
+    }
+
     std::string sd_cpp_extra_args_str = extract_and_remove_sd_cpp_extra_args(request.gen_params.prompt);
     if (!sd_cpp_extra_args_str.empty() && !request.gen_params.from_json_str(sd_cpp_extra_args_str)) {
         error_message = "invalid sd_cpp_extra_args";
@@ -228,7 +247,7 @@ static bool build_sdapi_img_gen_request(const json& j,
     }
 
     // Intentionally disable prompt-embedded LoRA tag parsing for server APIs.
-    if (!request.gen_params.resolve_and_validate(IMG_GEN, "", true)) {
+    if (!request.gen_params.resolve_and_validate(IMG_GEN, "", runtime.ctx_params->hires_upscalers_dir, true)) {
         error_message = "invalid params";
         return false;
     }
@@ -246,6 +265,11 @@ void register_sdapi_endpoints(httplib::Server& svr, ServerRuntime& rt) {
                 res.set_content(R"({"error":"empty body"})", "application/json");
                 return;
             }
+            if (!runtime_supports_generation_mode(*runtime, IMG_GEN)) {
+                res.status = 400;
+                res.set_content(json({{"error", unsupported_generation_mode_error(IMG_GEN)}}).dump(), "application/json");
+                return;
+            }
 
             json j = json::parse(req.body);
             ImgGenJobRequest request;
@@ -342,6 +366,52 @@ void register_sdapi_endpoints(httplib::Server& svr, ServerRuntime& rt) {
         res.set_content(result.dump(), "application/json");
     });
 
+    svr.Get("/sdapi/v1/upscalers", [runtime](const httplib::Request&, httplib::Response& res) {
+        refresh_upscaler_cache(*runtime);
+
+        auto make_builtin = [](const char* name) {
+            json item;
+            item["name"]       = name;
+            item["model_name"] = nullptr;
+            item["model_path"] = nullptr;
+            item["model_url"]  = nullptr;
+            item["scale"]      = 4;
+            return item;
+        };
+
+        json result = json::array();
+        result.push_back(make_builtin("None"));
+        result.push_back(make_builtin("Lanczos"));
+        result.push_back(make_builtin("Nearest"));
+
+        {
+            std::lock_guard<std::mutex> lock(*runtime->upscaler_mutex);
+            for (const auto& e : *runtime->upscaler_cache) {
+                json item;
+                item["name"]       = e.name;
+                item["model_name"] = e.model_name;
+                item["model_path"] = e.fullpath;
+                item["model_url"]  = nullptr;
+                item["scale"]      = e.scale;
+                result.push_back(item);
+            }
+        }
+
+        res.set_content(result.dump(), "application/json");
+    });
+
+    svr.Get("/sdapi/v1/latent-upscale-modes", [](const httplib::Request&, httplib::Response& res) {
+        json result = json::array({
+            {{"name", "Latent"}},
+            {{"name", "Latent (nearest)"}},
+            {{"name", "Latent (nearest-exact)"}},
+            {{"name", "Latent (antialiased)"}},
+            {{"name", "Latent (bicubic)"}},
+            {{"name", "Latent (bicubic antialiased)"}},
+        });
+        res.set_content(result.dump(), "application/json");
+    });
+
     svr.Get("/sdapi/v1/samplers", [runtime](const httplib::Request&, httplib::Response& res) {
         std::vector<std::string> sampler_names;
         sampler_names.push_back("default");

examples/server/routes_sdcpp.cpp

@@ -75,48 +75,33 @@ static fs::path resolve_display_model_path(const ServerRuntime& runtime) {
     return {};
 }
 
-static json make_capabilities_json(ServerRuntime& runtime) {
-    refresh_lora_cache(runtime);
-
-    AsyncJobManager& manager  = *runtime.async_job_manager;
-    const auto& defaults      = *runtime.default_gen_params;
-    const auto& sample_params = defaults.sample_params;
-    const auto& guidance      = sample_params.guidance;
-    const fs::path model_path = resolve_display_model_path(runtime);
-    json samplers             = json::array();
-    json schedulers           = json::array();
-    json output_formats       = json::array({"png", "jpeg"});
-    json available_loras      = json::array();
-
-    for (int i = 0; i < SAMPLE_METHOD_COUNT; ++i) {
-        samplers.push_back(sd_sample_method_name((sample_method_t)i));
-    }
-
-    for (int i = 0; i < SCHEDULER_COUNT; ++i) {
-        schedulers.push_back(sd_scheduler_name((scheduler_t)i));
-    }
-
-#ifdef SD_USE_WEBP
-    output_formats.push_back("webp");
-#endif
-
-    {
-        std::lock_guard<std::mutex> lock(*runtime.lora_mutex);
-        for (const auto& entry : *runtime.lora_cache) {
-            available_loras.push_back({
-                {"name", entry.name},
-                {"path", entry.path},
-            });
-        }
-    }
-
-    json result;
-    result["model"] = {
-        {"name", model_path.filename().u8string()},
-        {"stem", model_path.stem().u8string()},
-        {"path", model_path.u8string()},
+static json make_sample_params_json(const sd_sample_params_t& sample_params, const std::vector<int>& skip_layers) {
+    const auto& guidance = sample_params.guidance;
+    return {
+        {"scheduler", capability_scheduler_name(sample_params.scheduler)},
+        {"sample_method", capability_sample_method_name(sample_params.sample_method)},
+        {"sample_steps", sample_params.sample_steps},
+        {"eta", finite_number_or_null(sample_params.eta)},
+        {"shifted_timestep", sample_params.shifted_timestep},
+        {"flow_shift", finite_number_or_null(sample_params.flow_shift)},
+        {"guidance",
+         {
+             {"txt_cfg", guidance.txt_cfg},
+             {"img_cfg", finite_number_or_null(guidance.img_cfg)},
+             {"distilled_guidance", guidance.distilled_guidance},
+             {"slg",
+              {
+                  {"layers", skip_layers},
+                  {"layer_start", guidance.slg.layer_start},
+                  {"layer_end", guidance.slg.layer_end},
+                  {"scale", guidance.slg.scale},
+              }},
+         }},
     };
-    result["defaults"] = {
+}
+
+static json make_img_gen_defaults_json(const SDGenerationParams& defaults, const std::string& output_format) {
+    return {
         {"prompt", defaults.prompt},
         {"negative_prompt", defaults.negative_prompt},
         {"clip_skip", defaults.clip_skip},
@@ -128,59 +113,228 @@ static json make_capabilities_json(ServerRuntime& runtime) {
         {"auto_resize_ref_image", defaults.auto_resize_ref_image},
         {"increase_ref_index", defaults.increase_ref_index},
         {"control_strength", defaults.control_strength},
-        {"sample_params",
+        {"sample_params", make_sample_params_json(defaults.sample_params, defaults.skip_layers)},
+        {"hires",
          {
-             {"scheduler", capability_scheduler_name(sample_params.scheduler)},
-             {"sample_method", capability_sample_method_name(sample_params.sample_method)},
-             {"sample_steps", sample_params.sample_steps},
-             {"eta", finite_number_or_null(sample_params.eta)},
-             {"shifted_timestep", sample_params.shifted_timestep},
-             {"flow_shift", finite_number_or_null(sample_params.flow_shift)},
-             {"guidance",
-              {
-                  {"txt_cfg", guidance.txt_cfg},
-                  {"img_cfg", finite_number_or_null(guidance.img_cfg)},
-                  {"distilled_guidance", guidance.distilled_guidance},
-                  {"slg",
-                   {
-                       {"layers", defaults.skip_layers},
-                       {"layer_start", guidance.slg.layer_start},
-                       {"layer_end", guidance.slg.layer_end},
-                       {"scale", guidance.slg.scale},
-                   }},
-              }},
+             {"enabled", defaults.hires_enabled},
+             {"upscaler", defaults.hires_upscaler},
+             {"scale", defaults.hires_scale},
+             {"target_width", defaults.hires_width},
+             {"target_height", defaults.hires_height},
+             {"steps", defaults.hires_steps},
+             {"denoising_strength", defaults.hires_denoising_strength},
+             {"upscale_tile_size", defaults.hires_upscale_tile_size},
          }},
         {"vae_tiling_params", make_vae_tiling_json(defaults.vae_tiling_params)},
         {"cache_mode", defaults.cache_mode},
         {"cache_option", defaults.cache_option},
         {"scm_mask", defaults.scm_mask},
         {"scm_policy_dynamic", defaults.scm_policy_dynamic},
-        {"output_format", "png"},
+        {"output_format", output_format},
         {"output_compression", 100},
     };
-    result["limits"] = {
-        {"min_width", 64},
-        {"max_width", 4096},
-        {"min_height", 64},
-        {"max_height", 4096},
-        {"max_batch_count", 8},
-        {"max_queue_size", manager.max_pending_jobs},
+}
+
+static json make_vid_gen_defaults_json(const SDGenerationParams& defaults, const std::string& output_format) {
+    return {
+        {"prompt", defaults.prompt},
+        {"negative_prompt", defaults.negative_prompt},
+        {"clip_skip", defaults.clip_skip},
+        {"width", defaults.width > 0 ? defaults.width : 512},
+        {"height", defaults.height > 0 ? defaults.height : 512},
+        {"strength", defaults.strength},
+        {"seed", defaults.seed},
+        {"video_frames", defaults.video_frames},
+        {"fps", defaults.fps},
+        {"moe_boundary", defaults.moe_boundary},
+        {"vace_strength", defaults.vace_strength},
+        {"sample_params", make_sample_params_json(defaults.sample_params, defaults.skip_layers)},
+        {"high_noise_sample_params", make_sample_params_json(defaults.high_noise_sample_params, defaults.high_noise_skip_layers)},
+        {"vae_tiling_params", make_vae_tiling_json(defaults.vae_tiling_params)},
+        {"cache_mode", defaults.cache_mode},
+        {"cache_option", defaults.cache_option},
+        {"scm_mask", defaults.scm_mask},
+        {"scm_policy_dynamic", defaults.scm_policy_dynamic},
+        {"output_format", output_format},
+        {"output_compression", 100},
     };
-    result["samplers"]       = samplers;
-    result["schedulers"]     = schedulers;
-    result["output_formats"] = output_formats;
-    result["features"]       = {
-              {"init_image", true},
-              {"mask_image", true},
-              {"control_image", true},
-              {"ref_images", true},
-              {"lora", true},
-              {"vae_tiling", true},
-              {"cache", true},
+}
+
+static json make_img_gen_features_json() {
+    return {
+        {"init_image", true},
+        {"mask_image", true},
+        {"control_image", true},
+        {"ref_images", true},
+        {"lora", true},
+        {"vae_tiling", true},
+        {"hires", true},
+        {"cache", true},
+        {"cancel_queued", true},
+        {"cancel_generating", false},
+    };
+}
+
+static json make_vid_gen_features_json() {
+    return {
+        {"init_image", true},
+        {"end_image", true},
+        {"control_frames", true},
+        {"high_noise_sample_params", true},
+        {"lora", true},
+        {"vae_tiling", true},
+        {"cache", true},
+        {"cancel_queued", true},
+        {"cancel_generating", false},
+    };
+}
+
+static json make_capabilities_json(ServerRuntime& runtime) {
+    refresh_lora_cache(runtime);
+    refresh_upscaler_cache(runtime);
+
+    AsyncJobManager& manager  = *runtime.async_job_manager;
+    const auto& defaults      = *runtime.default_gen_params;
+    const fs::path model_path = resolve_display_model_path(runtime);
+    const bool supports_img   = runtime_supports_generation_mode(runtime, IMG_GEN);
+    const bool supports_vid   = runtime_supports_generation_mode(runtime, VID_GEN);
+    json samplers             = json::array();
+    json schedulers           = json::array();
+    json image_output_formats = supported_img_output_formats();
+    json video_output_formats = supported_vid_output_formats();
+    json available_loras      = json::array();
+    json available_upscalers  = json::array();
+    json supported_modes      = json::array();
+
+    for (int i = 0; i < SAMPLE_METHOD_COUNT; ++i) {
+        samplers.push_back(sd_sample_method_name((sample_method_t)i));
+    }
+
+    for (int i = 0; i < SCHEDULER_COUNT; ++i) {
+        schedulers.push_back(sd_scheduler_name((scheduler_t)i));
+    }
+
+    {
+        std::lock_guard<std::mutex> lock(*runtime.lora_mutex);
+        for (const auto& entry : *runtime.lora_cache) {
+            available_loras.push_back({
+                {"name", entry.name},
+                {"path", entry.path},
+            });
+        }
+    }
+
+    available_upscalers.push_back({
+        {"name", "None"},
+    });
+    available_upscalers.push_back({
+        {"name", "Lanczos"},
+    });
+    available_upscalers.push_back({
+        {"name", "Nearest"},
+    });
+    available_upscalers.push_back({
+        {"name", "Latent"},
+    });
+    available_upscalers.push_back({
+        {"name", "Latent (nearest)"},
+    });
+    available_upscalers.push_back({
+        {"name", "Latent (nearest-exact)"},
+    });
+    available_upscalers.push_back({
+        {"name", "Latent (antialiased)"},
+    });
+    available_upscalers.push_back({
+        {"name", "Latent (bicubic)"},
+    });
+    available_upscalers.push_back({
+        {"name", "Latent (bicubic antialiased)"},
+    });
+    {
+        std::lock_guard<std::mutex> lock(*runtime.upscaler_mutex);
+        for (const auto& entry : *runtime.upscaler_cache) {
+            available_upscalers.push_back({
+                {"name", entry.name},
+            });
+        }
+    }
+
+    if (supports_img) {
+        supported_modes.push_back("img_gen");
+    }
+    if (supports_vid) {
+        supported_modes.push_back("vid_gen");
+    }
+
+    std::string default_img_output_format = "png";
+    std::string default_vid_output_format = "avi";
+    if (!image_output_formats.empty()) {
+        default_img_output_format = image_output_formats[0].get<std::string>();
+    }
+    if (!video_output_formats.empty()) {
+        default_vid_output_format = video_output_formats[0].get<std::string>();
+    }
+
+    json defaults_by_mode       = json::object();
+    json output_formats_by_mode = json::object();
+    json features_by_mode       = json::object();
+    if (supports_img) {
+        defaults_by_mode["img_gen"]       = make_img_gen_defaults_json(defaults, default_img_output_format);
+        output_formats_by_mode["img_gen"] = image_output_formats;
+        features_by_mode["img_gen"]       = make_img_gen_features_json();
+    }
+    if (supports_vid) {
+        defaults_by_mode["vid_gen"]       = make_vid_gen_defaults_json(defaults, default_vid_output_format);
+        output_formats_by_mode["vid_gen"] = video_output_formats;
+        features_by_mode["vid_gen"]       = make_vid_gen_features_json();
+    }
+
+    json top_level_defaults       = json::object();
+    json top_level_output_formats = json::array();
+    json top_level_features       = {
               {"cancel_queued", true},
               {"cancel_generating", false},
     };
-    result["loras"] = available_loras;
+    std::string current_mode = "";
+    if (supports_img) {
+        current_mode             = "img_gen";
+        top_level_defaults       = defaults_by_mode["img_gen"];
+        top_level_output_formats = output_formats_by_mode["img_gen"];
+        top_level_features       = features_by_mode["img_gen"];
+    } else if (supports_vid) {
+        current_mode             = "vid_gen";
+        top_level_defaults       = defaults_by_mode["vid_gen"];
+        top_level_output_formats = output_formats_by_mode["vid_gen"];
+        top_level_features       = features_by_mode["vid_gen"];
+    }
+
+    json result;
+    result["model"] = {
+        {"name", model_path.filename().u8string()},
+        {"stem", model_path.stem().u8string()},
+        {"path", model_path.u8string()},
+    };
+    result["current_mode"]     = current_mode;
+    result["supported_modes"]  = supported_modes;
+    result["defaults"]         = top_level_defaults;
+    result["defaults_by_mode"] = defaults_by_mode;
+    result["limits"]           = {
+                  {"min_width", 64},
+                  {"max_width", 4096},
+                  {"min_height", 64},
+                  {"max_height", 4096},
+                  {"max_batch_count", 8},
+                  {"max_queue_size", manager.max_pending_jobs},
+    };
+    result["samplers"]               = samplers;
+    result["schedulers"]             = schedulers;
+    result["output_formats"]         = top_level_output_formats;
+    result["output_formats_by_mode"] = output_formats_by_mode;
+    result["features"]               = top_level_features;
+    result["features_by_mode"]       = features_by_mode;
+    result["loras"]                  = available_loras;
+    result["upscalers"]              = available_upscalers;
     return result;
 }
 
@@ -204,7 +358,34 @@ static bool parse_img_gen_request(const json& body,
         return false;
     }
     // Intentionally disable prompt-embedded LoRA tag parsing for server APIs.
-    if (!request.gen_params.resolve_and_validate(IMG_GEN, "", true)) {
+    if (!request.gen_params.resolve_and_validate(IMG_GEN, "", runtime.ctx_params->hires_upscalers_dir, true)) {
+        error_message = "invalid generation parameters";
+        return false;
+    }
+    return true;
+}
+
+static bool parse_vid_gen_request(const json& body,
+                                  ServerRuntime& runtime,
+                                  VidGenJobRequest& request,
+                                  std::string& error_message) {
+    request.gen_params = *runtime.default_gen_params;
+
+    refresh_lora_cache(runtime);
+    if (!request.gen_params.from_json_str(body.dump(), [&](const std::string& path) {
+            return get_lora_full_path(runtime, path);
+        })) {
+        error_message = "invalid generation parameters";
+        return false;
+    }
+
+    std::string output_format = body.value("output_format", "webm");
+    int output_compression    = body.value("output_compression", 100);
+    if (!assign_output_options(request, output_format, output_compression, error_message)) {
+        return false;
+    }
+    // Intentionally disable prompt-embedded LoRA tag parsing for server APIs.
+    if (!request.gen_params.resolve_and_validate(VID_GEN, "", runtime.ctx_params->hires_upscalers_dir, true)) {
         error_message = "invalid generation parameters";
         return false;
     }
@@ -226,6 +407,11 @@ void register_sdcpp_api_endpoints(httplib::Server& svr, ServerRuntime& rt) {
                 res.set_content(R"({"error":"empty body"})", "application/json");
                 return;
             }
+            if (!runtime_supports_generation_mode(*runtime, IMG_GEN)) {
+                res.status = 400;
+                res.set_content(json({{"error", unsupported_generation_mode_error(IMG_GEN)}}).dump(), "application/json");
+                return;
+            }
 
             json body = json::parse(req.body);
             ImgGenJobRequest request;
@@ -276,9 +462,66 @@ void register_sdcpp_api_endpoints(httplib::Server& svr, ServerRuntime& rt) {
         }
     });
 
-    svr.Post("/sdcpp/v1/vid_gen", [](const httplib::Request&, httplib::Response& res) {
-        res.status = 501;
-        res.set_content(R"({"error":"vid_gen is reserved and not implemented yet"})", "application/json");
+    svr.Post("/sdcpp/v1/vid_gen", [runtime](const httplib::Request& req, httplib::Response& res) {
+        try {
+            if (req.body.empty()) {
+                res.status = 400;
+                res.set_content(R"({"error":"empty body"})", "application/json");
+                return;
+            }
+            if (!runtime_supports_generation_mode(*runtime, VID_GEN)) {
+                res.status = 400;
+                res.set_content(json({{"error", unsupported_generation_mode_error(VID_GEN)}}).dump(), "application/json");
+                return;
+            }
+
+            json body = json::parse(req.body);
+            VidGenJobRequest request;
+            std::string error_message;
+            if (!parse_vid_gen_request(body, *runtime, request, error_message)) {
+                res.status = 400;
+                res.set_content(json({{"error", error_message}}).dump(), "application/json");
+                return;
+            }
+
+            AsyncJobManager& manager                = *runtime->async_job_manager;
+            std::shared_ptr<AsyncGenerationJob> job = std::make_shared<AsyncGenerationJob>();
+            job->kind                               = AsyncJobKind::VidGen;
+            job->status                             = AsyncJobStatus::Queued;
+            job->created_at                         = unix_timestamp_now();
+            job->vid_gen                            = std::move(request);
+
+            {
+                std::lock_guard<std::mutex> lock(manager.mutex);
+                purge_expired_jobs(manager);
+                if (count_pending_jobs(manager) >= manager.max_pending_jobs) {
+                    res.status = 429;
+                    res.set_content(R"({"error":"job queue is full"})", "application/json");
+                    return;
+                }
+                job->id               = make_async_job_id(manager);
+                manager.jobs[job->id] = job;
+                manager.queue.push_back(job->id);
+            }
+
+            manager.cv.notify_one();
+
+            json out;
+            out["id"]       = job->id;
+            out["kind"]     = async_job_kind_name(job->kind);
+            out["status"]   = async_job_status_name(job->status);
+            out["created"]  = job->created_at;
+            out["poll_url"] = "/sdcpp/v1/jobs/" + job->id;
+
+            res.status = 202;
+            res.set_content(out.dump(), "application/json");
+        } catch (const json::parse_error& e) {
+            res.status = 400;
+            res.set_content(json({{"error", "invalid json"}, {"message", e.what()}}).dump(), "application/json");
+        } catch (const std::exception& e) {
+            res.status = 500;
+            res.set_content(json({{"error", "server_error"}, {"message", e.what()}}).dump(), "application/json");
+        }
     });
 
     svr.Get(R"(/sdcpp/v1/jobs/([A-Za-z0-9_\-]+))", [runtime](const httplib::Request& req, httplib::Response& res) {

examples/server/runtime.cpp

@@ -1,6 +1,7 @@
 #include "runtime.h"
 
 #include <algorithm>
+#include <cctype>
 #include <chrono>
 #include <cstdlib>
 #include <filesystem>
@@ -13,6 +14,18 @@
 
 namespace fs = std::filesystem;
 
+static std::string lower_ascii(std::string value) {
+    std::transform(value.begin(), value.end(), value.begin(), [](unsigned char c) {
+        return static_cast<char>(std::tolower(c));
+    });
+    return value;
+}
+
+static bool is_supported_model_ext(const fs::path& p) {
+    auto ext = lower_ascii(p.extension().string());
+    return ext == ".gguf" || ext == ".pt" || ext == ".pth" || ext == ".safetensors";
+}
+
 static const std::string k_base64_chars =
     "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
     "abcdefghijklmnopqrstuvwxyz"
@@ -45,6 +58,44 @@ std::string normalize_output_format(std::string output_format) {
     return output_format;
 }
 
+std::vector<std::string> supported_img_output_formats(bool allow_webp) {
+    std::vector<std::string> formats = {"png", "jpeg"};
+#ifdef SD_USE_WEBP
+    if (allow_webp) {
+        formats.push_back("webp");
+    }
+#else
+    (void)allow_webp;
+#endif
+    return formats;
+}
+
+std::vector<std::string> supported_vid_output_formats() {
+    std::vector<std::string> formats;
+#ifdef SD_USE_WEBM
+    formats.push_back("webm");
+#endif
+#ifdef SD_USE_WEBP
+    formats.push_back("webp");
+#endif
+    formats.push_back("avi");
+    return formats;
+}
+
+static std::string valid_vid_output_formats_message() {
+    const std::vector<std::string> formats = supported_vid_output_formats();
+
+    std::string message = "invalid output_format, must be one of [";
+    for (size_t i = 0; i < formats.size(); ++i) {
+        if (i > 0) {
+            message += ", ";
+        }
+        message += formats[i];
+    }
+    message += "]";
+    return message;
+}
+
 bool assign_output_options(ImgGenJobRequest& request,
                            std::string output_format,
                            int output_compression,
@@ -53,19 +104,88 @@ bool assign_output_options(ImgGenJobRequest& request,
     request.output_format      = normalize_output_format(std::move(output_format));
     request.output_compression = std::clamp(output_compression, 0, 100);
 
-    const bool valid_format = request.output_format == "png" ||
-                              request.output_format == "jpeg" ||
-                              (allow_webp && request.output_format == "webp");
+    const std::vector<std::string> valid_formats = supported_img_output_formats(allow_webp);
+    const bool valid_format                      = std::find(valid_formats.begin(),
+                                                             valid_formats.end(),
+                                                             request.output_format) != valid_formats.end();
     if (!valid_format) {
-        error_message = allow_webp
-                            ? "invalid output_format, must be one of [png, jpeg, webp]"
-                            : "invalid output_format, must be one of [png, jpeg]";
+        error_message = "invalid output_format, must be one of [";
+        for (size_t i = 0; i < valid_formats.size(); ++i) {
+            if (i > 0) {
+                error_message += ", ";
+            }
+            error_message += valid_formats[i];
+        }
+        error_message += "]";
         return false;
     }
 
     return true;
 }
 
+bool assign_output_options(VidGenJobRequest& request,
+                           std::string output_format,
+                           int output_compression,
+                           std::string& error_message) {
+    request.output_format      = normalize_output_format(std::move(output_format));
+    request.output_compression = std::clamp(output_compression, 0, 100);
+
+    if (request.output_format == "avi") {
+        return true;
+    }
+
+    if (request.output_format == "webm") {
+#ifdef SD_USE_WEBM
+        return true;
+#else
+        error_message = valid_vid_output_formats_message();
+        return false;
+#endif
+    }
+
+    if (request.output_format == "webp") {
+#ifdef SD_USE_WEBP
+        return true;
+#else
+        error_message = valid_vid_output_formats_message();
+        return false;
+#endif
+    }
+
+    error_message = valid_vid_output_formats_message();
+    return false;
+}
+
+std::string video_mime_type(const std::string& output_format) {
+    if (output_format == "webm") {
+        return "video/webm";
+    }
+    if (output_format == "webp") {
+        return "image/webp";
+    }
+    return "video/x-msvideo";
+}
+
+bool runtime_supports_generation_mode(const ServerRuntime& runtime, SDMode mode) {
+    if (mode == VID_GEN) {
+        return sd_ctx_supports_video_generation(runtime.sd_ctx);
+    }
+    if (mode == IMG_GEN) {
+        return sd_ctx_supports_image_generation(runtime.sd_ctx);
+    }
+    return true;
+}
+
+std::string unsupported_generation_mode_error(SDMode mode) {
+    if (mode == VID_GEN) {
+        return "loaded model does not support vid_gen";
+    }
+    if (mode == IMG_GEN) {
+        return "loaded model does not support img_gen";
+    }
+    return "loaded model does not support requested mode";
+}
+
 ArgOptions SDSvrParams::get_options() {
     ArgOptions options;
 
@@ -134,20 +254,12 @@ void refresh_lora_cache(ServerRuntime& rt) {
 
     fs::path lora_dir = rt.ctx_params->lora_model_dir;
     if (fs::exists(lora_dir) && fs::is_directory(lora_dir)) {
-        auto is_lora_ext = [](const fs::path& p) {
-            auto ext = p.extension().string();
-            std::transform(ext.begin(), ext.end(), ext.begin(), [](unsigned char c) {
-                return static_cast<char>(std::tolower(c));
-            });
-            return ext == ".gguf" || ext == ".pt" || ext == ".pth" || ext == ".safetensors";
-        };
-
         for (auto& entry : fs::recursive_directory_iterator(lora_dir)) {
             if (!entry.is_regular_file()) {
                 continue;
             }
             const fs::path& p = entry.path();
-            if (!is_lora_ext(p)) {
+            if (!is_supported_model_ext(p)) {
                 continue;
             }
 
@@ -179,6 +291,40 @@ std::string get_lora_full_path(ServerRuntime& rt, const std::string& path) {
     return it != rt.lora_cache->end() ? it->fullpath : "";
 }
 
+void refresh_upscaler_cache(ServerRuntime& rt) {
+    std::vector<UpscalerEntry> new_cache;
+
+    fs::path upscaler_dir = rt.ctx_params->hires_upscalers_dir;
+    if (fs::exists(upscaler_dir) && fs::is_directory(upscaler_dir)) {
+        for (auto& entry : fs::directory_iterator(upscaler_dir)) {
+            if (!entry.is_regular_file()) {
+                continue;
+            }
+            const fs::path& p = entry.path();
+            if (!is_supported_model_ext(p)) {
+                continue;
+            }
+
+            UpscalerEntry upscaler_entry;
+            upscaler_entry.name       = p.stem().u8string();
+            upscaler_entry.fullpath   = fs::absolute(p).lexically_normal().u8string();
+            upscaler_entry.model_name = "ESRGAN_4x";
+            upscaler_entry.path       = p.filename().u8string();
+
+            new_cache.push_back(std::move(upscaler_entry));
+        }
+    }
+
+    std::sort(new_cache.begin(), new_cache.end(), [](const UpscalerEntry& a, const UpscalerEntry& b) {
+        return a.name < b.name;
+    });
+
+    {
+        std::lock_guard<std::mutex> lock(*rt.upscaler_mutex);
+        *rt.upscaler_cache = std::move(new_cache);
+    }
+}
+
 int64_t unix_timestamp_now() {
     return std::chrono::duration_cast<std::chrono::seconds>(
                std::chrono::system_clock::now().time_since_epoch())

examples/server/runtime.h

@@ -37,6 +37,14 @@ struct LoraEntry {
     std::string fullpath;
 };
 
+struct UpscalerEntry {
+    std::string name;
+    std::string path;
+    std::string fullpath;
+    std::string model_name;
+    int scale = 4;
+};
+
 struct ServerRuntime {
     sd_ctx_t* sd_ctx;
     std::mutex* sd_ctx_mutex;
@@ -45,6 +53,8 @@ struct ServerRuntime {
     const SDGenerationParams* default_gen_params;
     std::vector<LoraEntry>* lora_cache;
     std::mutex* lora_mutex;
+    std::vector<UpscalerEntry>* upscaler_cache;
+    std::mutex* upscaler_mutex;
     AsyncJobManager* async_job_manager;
 };
 
@@ -58,13 +68,33 @@ struct ImgGenJobRequest {
     }
 };
 
+struct VidGenJobRequest {
+    SDGenerationParams gen_params;
+    std::string output_format = "webm";
+    int output_compression    = 100;
+
+    sd_vid_gen_params_t to_sd_vid_gen_params_t() {
+        return gen_params.to_sd_vid_gen_params_t();
+    }
+};
+
 std::string base64_encode(const std::vector<uint8_t>& bytes);
 std::string normalize_output_format(std::string output_format);
+std::vector<std::string> supported_img_output_formats(bool allow_webp = true);
+std::vector<std::string> supported_vid_output_formats();
 bool assign_output_options(ImgGenJobRequest& request,
                            std::string output_format,
                            int output_compression,
                            bool allow_webp,
                            std::string& error_message);
+bool assign_output_options(VidGenJobRequest& request,
+                           std::string output_format,
+                           int output_compression,
+                           std::string& error_message);
+std::string video_mime_type(const std::string& output_format);
+bool runtime_supports_generation_mode(const ServerRuntime& runtime, SDMode mode);
+std::string unsupported_generation_mode_error(SDMode mode);
 void refresh_lora_cache(ServerRuntime& rt);
 std::string get_lora_full_path(ServerRuntime& rt, const std::string& path);
+void refresh_upscaler_cache(ServerRuntime& rt);
 int64_t unix_timestamp_now();

format-code.sh

@@ -1,5 +1,5 @@
 for f in src/*.cpp src/*.h src/*.hpp src/tokenizers/*.h src/tokenizers/*.cpp src/tokenizers/vocab/*.h src/tokenizers/vocab/*.cpp \
-         examples/cli/*.cpp examples/cli/*.h examples/server/*.cpp \
+         src/model_io/*.h src/model_io/*.cpp examples/cli/*.cpp examples/cli/*.h examples/server/*.cpp \
          examples/common/*.hpp examples/common/*.h examples/common/*.cpp; do
   [[ "$f" == vocab* ]] && continue
   echo "formatting '$f'"

include/stable-diffusion.h

@@ -289,6 +289,32 @@ typedef struct {
     const char* path;
 } sd_lora_t;
 
+enum sd_hires_upscaler_t {
+    SD_HIRES_UPSCALER_NONE,
+    SD_HIRES_UPSCALER_LATENT,
+    SD_HIRES_UPSCALER_LATENT_NEAREST,
+    SD_HIRES_UPSCALER_LATENT_NEAREST_EXACT,
+    SD_HIRES_UPSCALER_LATENT_ANTIALIASED,
+    SD_HIRES_UPSCALER_LATENT_BICUBIC,
+    SD_HIRES_UPSCALER_LATENT_BICUBIC_ANTIALIASED,
+    SD_HIRES_UPSCALER_LANCZOS,
+    SD_HIRES_UPSCALER_NEAREST,
+    SD_HIRES_UPSCALER_MODEL,
+    SD_HIRES_UPSCALER_COUNT,
+};
+
+typedef struct {
+    bool enabled;
+    enum sd_hires_upscaler_t upscaler;
+    const char* model_path;
+    float scale;
+    int target_width;
+    int target_height;
+    int steps;
+    float denoising_strength;
+    int upscale_tile_size;
+} sd_hires_params_t;
+
 typedef struct {
     const sd_lora_t* loras;
     uint32_t lora_count;
@@ -312,6 +338,7 @@ typedef struct {
     sd_pm_params_t pm_params;
     sd_tiling_params_t vae_tiling_params;
     sd_cache_params_t cache;
+    sd_hires_params_t hires;
 } sd_img_gen_params_t;
 
 typedef struct {
@@ -348,6 +375,8 @@ SD_API void sd_set_progress_callback(sd_progress_cb_t cb, void* data);
 SD_API void sd_set_preview_callback(sd_preview_cb_t cb, enum preview_t mode, int interval, bool denoised, bool noisy, void* data);
 SD_API int32_t sd_get_num_physical_cores();
 SD_API const char* sd_get_system_info();
+SD_API bool sd_ctx_supports_image_generation(const sd_ctx_t* sd_ctx);
+SD_API bool sd_ctx_supports_video_generation(const sd_ctx_t* sd_ctx);
 
 SD_API const char* sd_type_name(enum sd_type_t type);
 SD_API enum sd_type_t str_to_sd_type(const char* str);
@@ -363,8 +392,11 @@ SD_API const char* sd_preview_name(enum preview_t preview);
 SD_API enum preview_t str_to_preview(const char* str);
 SD_API const char* sd_lora_apply_mode_name(enum lora_apply_mode_t mode);
 SD_API enum lora_apply_mode_t str_to_lora_apply_mode(const char* str);
+SD_API const char* sd_hires_upscaler_name(enum sd_hires_upscaler_t upscaler);
+SD_API enum sd_hires_upscaler_t str_to_sd_hires_upscaler(const char* str);
 
 SD_API void sd_cache_params_init(sd_cache_params_t* cache_params);
+SD_API void sd_hires_params_init(sd_hires_params_t* hires_params);
 
 SD_API void sd_ctx_params_init(sd_ctx_params_t* sd_ctx_params);
 SD_API char* sd_ctx_params_to_str(const sd_ctx_params_t* sd_ctx_params);

src/convert.cpp

@@ -0,0 +1,138 @@
+#include <cstring>
+#include <mutex>
+#include <regex>
+#include <vector>
+
+#include "model.h"
+#include "model_io/gguf_io.h"
+#include "model_io/safetensors_io.h"
+#include "util.h"
+
+#include "ggml-cpu.h"
+
+static ggml_type get_export_tensor_type(ModelLoader& model_loader,
+                                        const TensorStorage& tensor_storage,
+                                        ggml_type type,
+                                        const TensorTypeRules& tensor_type_rules) {
+    const std::string& name = tensor_storage.name;
+    ggml_type tensor_type   = tensor_storage.type;
+    ggml_type dst_type      = type;
+
+    for (const auto& tensor_type_rule : tensor_type_rules) {
+        std::regex pattern(tensor_type_rule.first);
+        if (std::regex_search(name, pattern)) {
+            dst_type = tensor_type_rule.second;
+            break;
+        }
+    }
+
+    if (model_loader.tensor_should_be_converted(tensor_storage, dst_type)) {
+        tensor_type = dst_type;
+    }
+
+    return tensor_type;
+}
+
+static bool load_tensors_for_export(ModelLoader& model_loader,
+                                    ggml_context* ggml_ctx,
+                                    ggml_type type,
+                                    const TensorTypeRules& tensor_type_rules,
+                                    std::vector<TensorWriteInfo>& tensors) {
+    std::mutex tensor_mutex;
+    auto on_new_tensor_cb = [&](const TensorStorage& tensor_storage, ggml_tensor** dst_tensor) -> bool {
+        const std::string& name = tensor_storage.name;
+        ggml_type tensor_type   = get_export_tensor_type(model_loader, tensor_storage, type, tensor_type_rules);
+
+        std::lock_guard<std::mutex> lock(tensor_mutex);
+        ggml_tensor* tensor = ggml_new_tensor(ggml_ctx, tensor_type, tensor_storage.n_dims, tensor_storage.ne);
+        if (tensor == nullptr) {
+            LOG_ERROR("ggml_new_tensor failed");
+            return false;
+        }
+        ggml_set_name(tensor, name.c_str());
+
+        if (!tensor->data) {
+            GGML_ASSERT(ggml_nelements(tensor) == 0);
+            // Avoid crashing writers by setting a dummy pointer for zero-sized tensors.
+            LOG_DEBUG("setting dummy pointer for zero-sized tensor %s", name.c_str());
+            tensor->data = ggml_get_mem_buffer(ggml_ctx);
+        }
+
+        TensorWriteInfo write_info;
+        write_info.tensor = tensor;
+        write_info.n_dims = tensor_storage.n_dims;
+        for (int i = 0; i < tensor_storage.n_dims; ++i) {
+            write_info.ne[i] = tensor_storage.ne[i];
+        }
+
+        *dst_tensor = tensor;
+        tensors.push_back(std::move(write_info));
+
+        return true;
+    };
+
+    bool success = model_loader.load_tensors(on_new_tensor_cb);
+    LOG_INFO("load tensors done");
+    return success;
+}
+
+bool convert(const char* input_path,
+             const char* vae_path,
+             const char* output_path,
+             sd_type_t output_type,
+             const char* tensor_type_rules,
+             bool convert_name) {
+    ModelLoader model_loader;
+
+    if (!model_loader.init_from_file(input_path)) {
+        LOG_ERROR("init model loader from file failed: '%s'", input_path);
+        return false;
+    }
+
+    if (vae_path != nullptr && strlen(vae_path) > 0) {
+        if (!model_loader.init_from_file(vae_path, "vae.")) {
+            LOG_ERROR("init model loader from file failed: '%s'", vae_path);
+            return false;
+        }
+    }
+    if (convert_name) {
+        model_loader.convert_tensors_name();
+    }
+
+    ggml_type type             = (ggml_type)output_type;
+    bool output_is_safetensors = ends_with(output_path, ".safetensors");
+    TensorTypeRules type_rules = parse_tensor_type_rules(tensor_type_rules);
+
+    auto backend    = ggml_backend_cpu_init();
+    size_t mem_size = 1 * 1024 * 1024;  // for padding
+    mem_size += model_loader.get_tensor_storage_map().size() * ggml_tensor_overhead();
+    mem_size += model_loader.get_params_mem_size(backend, type);
+    LOG_INFO("model tensors mem size: %.2fMB", mem_size / 1024.f / 1024.f);
+    ggml_context* ggml_ctx = ggml_init({mem_size, nullptr, false});
+
+    if (ggml_ctx == nullptr) {
+        LOG_ERROR("ggml_init failed for converter");
+        ggml_backend_free(backend);
+        return false;
+    }
+
+    std::vector<TensorWriteInfo> tensors;
+    bool success = load_tensors_for_export(model_loader, ggml_ctx, type, type_rules, tensors);
+    ggml_backend_free(backend);
+
+    std::string error;
+    if (success) {
+        if (output_is_safetensors) {
+            success = write_safetensors_file(output_path, tensors, &error);
+        } else {
+            success = write_gguf_file(output_path, tensors, &error);
+        }
+    }
+
+    if (!success && !error.empty()) {
+        LOG_ERROR("%s", error.c_str());
+    }
+
+    ggml_free(ggml_ctx);
+    return success;
+}

src/denoiser.hpp

@@ -970,6 +970,100 @@ static sd::Tensor<float> sample_dpmpp_2s_ancestral(denoise_cb_t model,
     return x;
 }
 
+static sd::Tensor<float> sample_dpmpp_2s_ancestral_flow(denoise_cb_t model,
+                                                        sd::Tensor<float> x,
+                                                        const std::vector<float>& sigmas,
+                                                        std::shared_ptr<RNG> rng,
+                                                        float eta = 1.0f) {
+    int steps = static_cast<int>(sigmas.size()) - 1;
+    for (int i = 0; i < steps; i++) {
+        float sigma    = sigmas[i];
+        float sigma_to = sigmas[i + 1];
+
+        bool opt_first_step = (1.0 - sigma < 1e-6);
+
+        auto denoised_opt = model(x, sigma, (opt_first_step ? 1 : -1) * (i + 1));
+        if (denoised_opt.empty()) {
+            return {};
+        }
+        sd::Tensor<float> denoised = std::move(denoised_opt);
+
+        if (sigma_to == 0.0f) {
+            // Euler method (final step, no noise)
+            // sigma_to == 0 --> sigma_down = 0, so:
+            //   x +                       d  * (sigma_down - sigma)
+            // = x + ((x - denoised) / sigma) * (sigma_down - sigma)
+            // = x + ((x - denoised) / sigma) * (         0 - sigma)
+            // = x + ((x - denoised)        ) * -1
+            // = x    -x + denoised
+            x = denoised;
+
+        } else {
+            auto [sigma_down, sigma_up, alpha_scale] = get_ancestral_step_flow(sigma, sigma_to, eta);
+            sd::Tensor<float> D_i;
+
+            if (opt_first_step) {
+                // the reformulated exp_s calc already accounts for this, but we can avoid
+                // a redundant model call for the typical sigma 1 at the first step:
+                // exp_s = sqrt((1-sigma)/sigma * (1-sigma_down)/sigma_down)
+                //       = sqrt((1-    1)/    1 * (1-sigma_down)/sigma_down)
+                //       = 0
+                // so sigma_s = 1 = sigma, and sigma_s_i_ratio = sigma_s / sigma = 1
+                // u = (x*sigma_s_i_ratio)+(denoised*(1.0f-sigma_s_i_ratio))
+                //   = (x*1)+(denoised*0) = x
+                // so D_i = model(u, sigma_s, i + 1)
+                //        = model(x, sigma,   i + 1)
+                //        = denoised
+                D_i = denoised;
+
+            } else {
+                float sigma_s;
+
+                // ref implementation would be:
+                // auto lambda_fn = [](float sigma) -> float {
+                //     return std::log((1.0f - sigma) / sigma); };
+                // auto sigma_fn = [](float lbda) -> float {
+                //     return 1.0f / (std::exp(lbda) + 1.0f); };
+                // t_i     = lambda_fn(sigma);
+                // t_down  = lambda_fn(sigma_down);
+                // float r = 0.5f;
+                // h       = t_down - t_i;
+                // s       = t_i + r * h;
+                // sigma_s = sigma_fn(s);
+
+                // assuming r is constant, we sidestep the singularity at sigma -> 1 by:
+                // s   = 0.5 * (lambda_fn(sigma)     + lambda_fn(sigma_down))
+                //     = 0.5 * (log((1-sigma)/sigma) + log((1-sigma_down)/sigma_down))
+                //     = 0.5 * log(((1-sigma)/sigma) *    ((1-sigma_down)/sigma_down))
+                //     = log(sqrt (((1-sigma)/sigma) *    ((1-sigma_down)/sigma_down)))
+                // so exp(s) = sqrt((1-sigma)/sigma  *     (1-sigma_down)/sigma_down)
+                // and sigma_s = sigma_fn(s) = 1.0f / (exp(s) + 1.0f)
+
+                float exp_s = std::sqrt(((1 - sigma) / sigma) * ((1 - sigma_down) / sigma_down));
+                sigma_s     = 1.0f / (exp_s + 1.0f);
+
+                float sigma_s_i_ratio = sigma_s / sigma;
+                sd::Tensor<float> u   = (x * sigma_s_i_ratio) + (denoised * (1.0f - sigma_s_i_ratio));
+
+                auto denoised2_opt = model(u, sigma_s, i + 1);
+                if (denoised2_opt.empty()) {
+                    return {};
+                }
+                D_i = std::move(denoised2_opt);
+            }
+
+            float sigma_down_i_ratio = sigma_down / sigma;
+            x                        = (x * sigma_down_i_ratio) + (D_i * (1.0f - sigma_down_i_ratio));
+
+            if (sigma_to > 0.0f && eta > 0.0f) {
+                x = alpha_scale * x + sd::Tensor<float>::randn_like(x, rng) * sigma_up;
+            }
+        }
+    }
+
+    return x;
+}
+
 static sd::Tensor<float> sample_dpmpp_2m(denoise_cb_t model,
                                          sd::Tensor<float> x,
                                          const std::vector<float>& sigmas) {
@@ -1041,7 +1135,8 @@ static sd::Tensor<float> sample_dpmpp_2m_v2(denoise_cb_t model,
 static sd::Tensor<float> sample_lcm(denoise_cb_t model,
                                     sd::Tensor<float> x,
                                     const std::vector<float>& sigmas,
-                                    std::shared_ptr<RNG> rng) {
+                                    std::shared_ptr<RNG> rng,
+                                    bool is_flow_denoiser) {
     int steps = static_cast<int>(sigmas.size()) - 1;
     for (int i = 0; i < steps; i++) {
         auto denoised_opt = model(x, sigmas[i], i + 1);
@@ -1050,6 +1145,9 @@ static sd::Tensor<float> sample_lcm(denoise_cb_t model,
         }
         x = std::move(denoised_opt);
         if (sigmas[i + 1] > 0) {
+            if (is_flow_denoiser) {
+                x *= (1 - sigmas[i + 1]);
+            }
             x += sd::Tensor<float>::randn_like(x, rng) * sigmas[i + 1];
         }
     }
@@ -1425,32 +1523,10 @@ static sd::Tensor<float> sample_ddim_trailing(denoise_cb_t model,
                                               const std::vector<float>& sigmas,
                                               std::shared_ptr<RNG> rng,
                                               float eta) {
-    float beta_start = 0.00085f;
-    float beta_end   = 0.0120f;
-    std::vector<double> alphas_cumprod(TIMESTEPS);
-    std::vector<double> compvis_sigmas(TIMESTEPS);
-    for (int i = 0; i < TIMESTEPS; i++) {
-        alphas_cumprod[i] =
-            (i == 0 ? 1.0f : alphas_cumprod[i - 1]) *
-            (1.0f -
-             std::pow(sqrtf(beta_start) +
-                          (sqrtf(beta_end) - sqrtf(beta_start)) *
-                              ((float)i / (TIMESTEPS - 1)),
-                      2));
-        compvis_sigmas[i] =
-            std::sqrt((1 - alphas_cumprod[i]) / alphas_cumprod[i]);
-    }
-
     int steps = static_cast<int>(sigmas.size()) - 1;
     for (int i = 0; i < steps; i++) {
-        int timestep      = static_cast<int>(roundf(TIMESTEPS - i * ((float)TIMESTEPS / steps))) - 1;
-        int prev_timestep = timestep - TIMESTEPS / steps;
-        float sigma       = static_cast<float>(compvis_sigmas[timestep]);
-        if (i == 0) {
-            x *= std::sqrt(sigma * sigma + 1) / sigma;
-        } else {
-            x *= std::sqrt(sigma * sigma + 1);
-        }
+        float sigma    = sigmas[i];
+        float sigma_to = sigmas[i + 1];
 
         auto model_output_opt = model(x, sigma, i + 1);
         if (model_output_opt.empty()) {
@@ -1459,8 +1535,8 @@ static sd::Tensor<float> sample_ddim_trailing(denoise_cb_t model,
         sd::Tensor<float> model_output = std::move(model_output_opt);
         model_output                   = (x - model_output) * (1.0f / sigma);
 
-        float alpha_prod_t      = static_cast<float>(alphas_cumprod[timestep]);
-        float alpha_prod_t_prev = static_cast<float>(prev_timestep >= 0 ? alphas_cumprod[prev_timestep] : alphas_cumprod[0]);
+        float alpha_prod_t      = 1.0f / (sigma * sigma + 1.0f);
+        float alpha_prod_t_prev = 1.0f / (sigma_to * sigma_to + 1.0f);
         float beta_prod_t       = 1.0f - alpha_prod_t;
 
         sd::Tensor<float> pred_original_sample = ((x / std::sqrt(sigma * sigma + 1)) -
@@ -1472,11 +1548,11 @@ static sd::Tensor<float> sample_ddim_trailing(denoise_cb_t model,
                          (1.0f - alpha_prod_t / alpha_prod_t_prev);
         float std_dev_t = eta * std::sqrt(variance);
 
-        x = std::sqrt(alpha_prod_t_prev) * pred_original_sample +
-            std::sqrt(1.0f - alpha_prod_t_prev - std::pow(std_dev_t, 2)) * model_output;
+        x = pred_original_sample +
+            std::sqrt((1.0f - alpha_prod_t_prev - std::pow(std_dev_t, 2)) / alpha_prod_t_prev) * model_output;
 
         if (eta > 0) {
-            x += std_dev_t * sd::Tensor<float>::randn_like(x, rng);
+            x += std_dev_t / std::sqrt(alpha_prod_t_prev) * sd::Tensor<float>::randn_like(x, rng);
         }
     }
     return x;
@@ -1503,19 +1579,26 @@ static sd::Tensor<float> sample_tcd(denoise_cb_t model,
             std::sqrt((1 - alphas_cumprod[i]) / alphas_cumprod[i]);
     }
 
-    int original_steps = 50;
-    int steps          = static_cast<int>(sigmas.size()) - 1;
-    for (int i = 0; i < steps; i++) {
-        int timestep      = TIMESTEPS - 1 - (TIMESTEPS / original_steps) * (int)floor(i * ((float)original_steps / steps));
-        int prev_timestep = i >= steps - 1 ? 0 : TIMESTEPS - 1 - (TIMESTEPS / original_steps) * (int)floor((i + 1) * ((float)original_steps / steps));
-        int timestep_s    = (int)floor((1 - eta) * prev_timestep);
-        float sigma       = static_cast<float>(compvis_sigmas[timestep]);
-
-        if (i == 0) {
-            x *= std::sqrt(sigma * sigma + 1) / sigma;
-        } else {
-            x *= std::sqrt(sigma * sigma + 1);
+    auto get_timestep_from_sigma = [&](float s) -> int {
+        auto it = std::lower_bound(compvis_sigmas.begin(), compvis_sigmas.end(), s);
+        if (it == compvis_sigmas.begin())
+            return 0;
+        if (it == compvis_sigmas.end())
+            return TIMESTEPS - 1;
+        int idx_high = static_cast<int>(std::distance(compvis_sigmas.begin(), it));
+        int idx_low  = idx_high - 1;
+        if (std::abs(compvis_sigmas[idx_high] - s) < std::abs(compvis_sigmas[idx_low] - s)) {
+            return idx_high;
         }
+        return idx_low;
+    };
+
+    int steps = static_cast<int>(sigmas.size()) - 1;
+    for (int i = 0; i < steps; i++) {
+        float sigma_to    = sigmas[i + 1];
+        int prev_timestep = get_timestep_from_sigma(sigma_to);
+        int timestep_s    = (int)floor((1 - eta) * prev_timestep);
+        float sigma       = sigmas[i];
 
         auto model_output_opt = model(x, sigma, i + 1);
         if (model_output_opt.empty()) {
@@ -1524,9 +1607,9 @@ static sd::Tensor<float> sample_tcd(denoise_cb_t model,
         sd::Tensor<float> model_output = std::move(model_output_opt);
         model_output                   = (x - model_output) * (1.0f / sigma);
 
-        float alpha_prod_t      = static_cast<float>(alphas_cumprod[timestep]);
+        float alpha_prod_t      = 1.0f / (sigma * sigma + 1.0f);
         float beta_prod_t       = 1.0f - alpha_prod_t;
-        float alpha_prod_t_prev = static_cast<float>(prev_timestep >= 0 ? alphas_cumprod[prev_timestep] : alphas_cumprod[0]);
+        float alpha_prod_t_prev = 1.0f / (sigma_to * sigma_to + 1.0f);
         float alpha_prod_s      = static_cast<float>(alphas_cumprod[timestep_s]);
         float beta_prod_s       = 1.0f - alpha_prod_s;
 
@@ -1534,12 +1617,12 @@ static sd::Tensor<float> sample_tcd(denoise_cb_t model,
                                                   std::sqrt(beta_prod_t) * model_output) *
                                                  (1.0f / std::sqrt(alpha_prod_t));
 
-        x = std::sqrt(alpha_prod_s) * pred_original_sample +
-            std::sqrt(beta_prod_s) * model_output;
+        x = std::sqrt(alpha_prod_s / alpha_prod_t_prev) * pred_original_sample +
+            std::sqrt(beta_prod_s / alpha_prod_t_prev) * model_output;
 
-        if (eta > 0 && i != steps - 1) {
+        if (eta > 0 && sigma_to > 0.0f) {
             x = std::sqrt(alpha_prod_t_prev / alpha_prod_s) * x +
-                std::sqrt(1.0f - alpha_prod_t_prev / alpha_prod_s) * sd::Tensor<float>::randn_like(x, rng);
+                std::sqrt(1.0f / alpha_prod_t_prev - 1.0f / alpha_prod_s) * sd::Tensor<float>::randn_like(x, rng);
         }
     }
     return x;
@@ -1566,13 +1649,16 @@ static sd::Tensor<float> sample_k_diffusion(sample_method_t method,
         case DPM2_SAMPLE_METHOD:
             return sample_dpm2(model, std::move(x), sigmas);
         case DPMPP2S_A_SAMPLE_METHOD:
-            return sample_dpmpp_2s_ancestral(model, std::move(x), sigmas, rng, eta);
+            if (is_flow_denoiser)
+                return sample_dpmpp_2s_ancestral_flow(model, std::move(x), sigmas, rng, eta);
+            else
+                return sample_dpmpp_2s_ancestral(model, std::move(x), sigmas, rng, eta);
         case DPMPP2M_SAMPLE_METHOD:
             return sample_dpmpp_2m(model, std::move(x), sigmas);
         case DPMPP2Mv2_SAMPLE_METHOD:
             return sample_dpmpp_2m_v2(model, std::move(x), sigmas);
         case LCM_SAMPLE_METHOD:
-            return sample_lcm(model, std::move(x), sigmas, rng);
+            return sample_lcm(model, std::move(x), sigmas, rng, is_flow_denoiser);
         case IPNDM_SAMPLE_METHOD:
             return sample_ipndm(model, std::move(x), sigmas);
         case IPNDM_V_SAMPLE_METHOD:

src/model.cpp

@@ -2,6 +2,7 @@
 #include <atomic>
 #include <chrono>
 #include <cstdarg>
+#include <cstdlib>
 #include <fstream>
 #include <functional>
 #include <mutex>
@@ -12,8 +13,11 @@
 #include <unordered_map>
 #include <vector>
 
-#include "gguf_reader.hpp"
 #include "model.h"
+#include "model_io/gguf_io.h"
+#include "model_io/safetensors_io.h"
+#include "model_io/torch_legacy_io.h"
+#include "model_io/torch_zip_io.h"
 #include "stable-diffusion.h"
 #include "util.h"
 
@@ -21,6 +25,7 @@
 #include "ggml-backend.h"
 #include "ggml-cpu.h"
 #include "ggml.h"
+#include "zip.h"
 
 #include "name_conversion.h"
 #include "stable-diffusion.h"
@@ -37,40 +42,6 @@
 #include "ggml-opencl.h"
 #endif
 
-#define ST_HEADER_SIZE_LEN 8
-
-uint64_t read_u64(uint8_t* buffer) {
-    // little endian
-    uint64_t value = 0;
-    value |= static_cast<int64_t>(buffer[7]) << 56;
-    value |= static_cast<int64_t>(buffer[6]) << 48;
-    value |= static_cast<int64_t>(buffer[5]) << 40;
-    value |= static_cast<int64_t>(buffer[4]) << 32;
-    value |= static_cast<int64_t>(buffer[3]) << 24;
-    value |= static_cast<int64_t>(buffer[2]) << 16;
-    value |= static_cast<int64_t>(buffer[1]) << 8;
-    value |= static_cast<int64_t>(buffer[0]);
-    return value;
-}
-
-int32_t read_int(uint8_t* buffer) {
-    // little endian
-    int value = 0;
-    value |= buffer[3] << 24;
-    value |= buffer[2] << 16;
-    value |= buffer[1] << 8;
-    value |= buffer[0];
-    return value;
-}
-
-uint16_t read_short(uint8_t* buffer) {
-    // little endian
-    uint16_t value = 0;
-    value |= buffer[1] << 8;
-    value |= buffer[0];
-    return value;
-}
-
 /*================================================= Preprocess ==================================================*/
 
 const char* unused_tensors[] = {
@@ -110,7 +81,7 @@ const char* unused_tensors[] = {
     "first_stage_model.bn.",
 };
 
-bool is_unused_tensor(std::string name) {
+bool is_unused_tensor(const std::string& name) {
     for (size_t i = 0; i < sizeof(unused_tensors) / sizeof(const char*); i++) {
         if (starts_with(name, unused_tensors[i])) {
             return true;
@@ -250,79 +221,6 @@ void ModelLoader::add_tensor_storage(const TensorStorage& tensor_storage) {
     tensor_storage_map[tensor_storage.name] = tensor_storage;
 }
 
-bool is_zip_file(const std::string& file_path) {
-    zip_t* zip = zip_open(file_path.c_str(), 0, 'r');
-    if (zip == nullptr) {
-        return false;
-    }
-    zip_close(zip);
-    return true;
-}
-
-bool is_gguf_file(const std::string& file_path) {
-    std::ifstream file(file_path, std::ios::binary);
-    if (!file.is_open()) {
-        return false;
-    }
-
-    char magic[4];
-
-    file.read(magic, sizeof(magic));
-    if (!file) {
-        return false;
-    }
-    for (uint32_t i = 0; i < sizeof(magic); i++) {
-        if (magic[i] != GGUF_MAGIC[i]) {
-            return false;
-        }
-    }
-
-    return true;
-}
-
-bool is_safetensors_file(const std::string& file_path) {
-    std::ifstream file(file_path, std::ios::binary);
-    if (!file.is_open()) {
-        return false;
-    }
-
-    // get file size
-    file.seekg(0, file.end);
-    size_t file_size_ = file.tellg();
-    file.seekg(0, file.beg);
-
-    // read header size
-    if (file_size_ <= ST_HEADER_SIZE_LEN) {
-        return false;
-    }
-
-    uint8_t header_size_buf[ST_HEADER_SIZE_LEN];
-    file.read((char*)header_size_buf, ST_HEADER_SIZE_LEN);
-    if (!file) {
-        return false;
-    }
-
-    size_t header_size_ = read_u64(header_size_buf);
-    if (header_size_ >= file_size_ || header_size_ <= 2) {
-        return false;
-    }
-
-    // read header
-    std::vector<char> header_buf;
-    header_buf.resize(header_size_ + 1);
-    header_buf[header_size_] = '\0';
-    file.read(header_buf.data(), header_size_);
-    if (!file) {
-        return false;
-    }
-    try {
-        nlohmann::json header_ = nlohmann::json::parse(header_buf.data());
-    } catch (const std::exception&) {
-        return false;
-    }
-    return true;
-}
-
 bool ModelLoader::init_from_file(const std::string& file_path, const std::string& prefix) {
     if (is_directory(file_path)) {
         LOG_INFO("load %s using diffusers format", file_path.c_str());
@@ -333,9 +231,12 @@ bool ModelLoader::init_from_file(const std::string& file_path, const std::string
     } else if (is_safetensors_file(file_path)) {
         LOG_INFO("load %s using safetensors format", file_path.c_str());
         return init_from_safetensors_file(file_path, prefix);
-    } else if (is_zip_file(file_path)) {
-        LOG_INFO("load %s using checkpoint format", file_path.c_str());
-        return init_from_ckpt_file(file_path, prefix);
+    } else if (is_torch_zip_file(file_path)) {
+        LOG_INFO("load %s using torch zip format", file_path.c_str());
+        return init_from_torch_zip_file(file_path, prefix);
+    } else if (init_from_torch_legacy_file(file_path, prefix)) {
+        LOG_INFO("load %s using torch legacy format", file_path.c_str());
+        return true;
     } else {
         if (file_exists(file_path)) {
             LOG_WARN("unknown format %s", file_path.c_str());
@@ -375,242 +276,121 @@ bool ModelLoader::init_from_file_and_convert_name(const std::string& file_path,
 
 bool ModelLoader::init_from_gguf_file(const std::string& file_path, const std::string& prefix) {
     LOG_DEBUG("init from '%s'", file_path.c_str());
+
+    std::vector<TensorStorage> tensor_storages;
+    std::string error;
+    if (!read_gguf_file(file_path, tensor_storages, &error)) {
+        LOG_ERROR("%s", error.c_str());
+        return false;
+    }
+
     file_paths_.push_back(file_path);
     size_t file_index = file_paths_.size() - 1;
 
-    gguf_context* ctx_gguf_ = nullptr;
-    ggml_context* ctx_meta_ = nullptr;
+    for (auto& tensor_storage : tensor_storages) {
+        // LOG_DEBUG("%s", tensor_storage.name.c_str());
 
-    ctx_gguf_ = gguf_init_from_file(file_path.c_str(), {true, &ctx_meta_});
-    if (!ctx_gguf_) {
-        LOG_ERROR("failed to open '%s' with gguf_init_from_file. Try to open it with GGUFReader.", file_path.c_str());
-        GGUFReader gguf_reader;
-        if (!gguf_reader.load(file_path)) {
-            LOG_ERROR("failed to open '%s' with GGUFReader.", file_path.c_str());
-            return false;
+        if (!starts_with(tensor_storage.name, prefix)) {
+            tensor_storage.name = prefix + tensor_storage.name;
         }
-
-        size_t data_offset = gguf_reader.data_offset();
-        for (const auto& gguf_tensor_info : gguf_reader.tensors()) {
-            std::string name = gguf_tensor_info.name;
-            if (!starts_with(name, prefix)) {
-                name = prefix + name;
-            }
-
-            TensorStorage tensor_storage(
-                name,
-                gguf_tensor_info.type,
-                gguf_tensor_info.shape.data(),
-                static_cast<int>(gguf_tensor_info.shape.size()),
-                file_index,
-                data_offset + gguf_tensor_info.offset);
-
-            // LOG_DEBUG("%s %s", name.c_str(), tensor_storage.to_string().c_str());
-
-            add_tensor_storage(tensor_storage);
-        }
-
-        return true;
-    }
-
-    int n_tensors = static_cast<int>(gguf_get_n_tensors(ctx_gguf_));
-
-    size_t total_size  = 0;
-    size_t data_offset = gguf_get_data_offset(ctx_gguf_);
-    for (int i = 0; i < n_tensors; i++) {
-        std::string name   = gguf_get_tensor_name(ctx_gguf_, i);
-        ggml_tensor* dummy = ggml_get_tensor(ctx_meta_, name.c_str());
-        size_t offset      = data_offset + gguf_get_tensor_offset(ctx_gguf_, i);
-
-        // LOG_DEBUG("%s", name.c_str());
-
-        if (!starts_with(name, prefix)) {
-            name = prefix + name;
-        }
-
-        TensorStorage tensor_storage(name, dummy->type, dummy->ne, ggml_n_dims(dummy), file_index, offset);
-
-        GGML_ASSERT(ggml_nbytes(dummy) == tensor_storage.nbytes());
+        tensor_storage.file_index = file_index;
 
         add_tensor_storage(tensor_storage);
     }
 
-    gguf_free(ctx_gguf_);
-    ggml_free(ctx_meta_);
-
     return true;
 }
 
 /*================================================= SafeTensorsModelLoader ==================================================*/
 
-ggml_type str_to_ggml_type(const std::string& dtype) {
-    ggml_type ttype = GGML_TYPE_COUNT;
-    if (dtype == "F16") {
-        ttype = GGML_TYPE_F16;
-    } else if (dtype == "BF16") {
-        ttype = GGML_TYPE_BF16;
-    } else if (dtype == "F32") {
-        ttype = GGML_TYPE_F32;
-    } else if (dtype == "F64") {
-        ttype = GGML_TYPE_F32;
-    } else if (dtype == "F8_E4M3") {
-        ttype = GGML_TYPE_F16;
-    } else if (dtype == "F8_E5M2") {
-        ttype = GGML_TYPE_F16;
-    } else if (dtype == "I64") {
-        ttype = GGML_TYPE_I32;
-    }
-    return ttype;
-}
-
-// https://huggingface.co/docs/safetensors/index
 bool ModelLoader::init_from_safetensors_file(const std::string& file_path, const std::string& prefix) {
     LOG_DEBUG("init from '%s', prefix = '%s'", file_path.c_str(), prefix.c_str());
+
+    std::vector<TensorStorage> tensor_storages;
+    std::string error;
+    if (!read_safetensors_file(file_path, tensor_storages, &error)) {
+        LOG_ERROR("%s", error.c_str());
+        return false;
+    }
+
     file_paths_.push_back(file_path);
     size_t file_index = file_paths_.size() - 1;
-    std::ifstream file(file_path, std::ios::binary);
-    if (!file.is_open()) {
-        LOG_ERROR("failed to open '%s'", file_path.c_str());
-        file_paths_.pop_back();
-        return false;
-    }
 
-    // get file size
-    file.seekg(0, file.end);
-    size_t file_size_ = file.tellg();
-    file.seekg(0, file.beg);
-
-    // read header size
-    if (file_size_ <= ST_HEADER_SIZE_LEN) {
-        LOG_ERROR("invalid safetensor file '%s'", file_path.c_str());
-        file_paths_.pop_back();
-        return false;
-    }
-
-    uint8_t header_size_buf[ST_HEADER_SIZE_LEN];
-    file.read((char*)header_size_buf, ST_HEADER_SIZE_LEN);
-    if (!file) {
-        LOG_ERROR("read safetensors header size failed: '%s'", file_path.c_str());
-        return false;
-    }
-
-    size_t header_size_ = read_u64(header_size_buf);
-    if (header_size_ >= file_size_) {
-        LOG_ERROR("invalid safetensor file '%s'", file_path.c_str());
-        file_paths_.pop_back();
-        return false;
-    }
-
-    // read header
-    std::vector<char> header_buf;
-    header_buf.resize(header_size_ + 1);
-    header_buf[header_size_] = '\0';
-    file.read(header_buf.data(), header_size_);
-    if (!file) {
-        LOG_ERROR("read safetensors header failed: '%s'", file_path.c_str());
-        file_paths_.pop_back();
-        return false;
-    }
-
-    nlohmann::json header_;
-    try {
-        header_ = nlohmann::json::parse(header_buf.data());
-    } catch (const std::exception&) {
-        LOG_ERROR("parsing safetensors header failed", file_path.c_str());
-        file_paths_.pop_back();
-        return false;
-    }
-
-    for (auto& item : header_.items()) {
-        std::string name           = item.key();
-        nlohmann::json tensor_info = item.value();
-        // LOG_DEBUG("%s %s\n", name.c_str(), tensor_info.dump().c_str());
-
-        if (name == "__metadata__") {
+    for (auto& tensor_storage : tensor_storages) {
+        if (is_unused_tensor(tensor_storage.name)) {
             continue;
         }
 
-        if (is_unused_tensor(name)) {
-            continue;
-        }
-
-        std::string dtype    = tensor_info["dtype"];
-        nlohmann::json shape = tensor_info["shape"];
-
-        if (dtype == "U8") {
-            continue;
-        }
-
-        size_t begin = tensor_info["data_offsets"][0].get<size_t>();
-        size_t end   = tensor_info["data_offsets"][1].get<size_t>();
-
-        ggml_type type = str_to_ggml_type(dtype);
-        if (type == GGML_TYPE_COUNT) {
-            LOG_ERROR("unsupported dtype '%s' (tensor '%s')", dtype.c_str(), name.c_str());
-            return false;
-        }
-
-        if (shape.size() > SD_MAX_DIMS) {
-            LOG_ERROR("invalid tensor '%s'", name.c_str());
-            return false;
-        }
-
-        int n_dims              = (int)shape.size();
-        int64_t ne[SD_MAX_DIMS] = {1, 1, 1, 1, 1};
-        for (int i = 0; i < n_dims; i++) {
-            ne[i] = shape[i].get<int64_t>();
-        }
-
-        if (n_dims == 5) {
-            n_dims = 4;
-            ne[0]  = ne[0] * ne[1];
-            ne[1]  = ne[2];
-            ne[2]  = ne[3];
-            ne[3]  = ne[4];
-        }
-
-        // ggml_n_dims returns 1 for scalars
-        if (n_dims == 0) {
-            n_dims = 1;
-        }
-
-        if (!starts_with(name, prefix)) {
-            name = prefix + name;
-        }
-
-        TensorStorage tensor_storage(name, type, ne, n_dims, file_index, ST_HEADER_SIZE_LEN + header_size_ + begin);
-        tensor_storage.reverse_ne();
-
-        size_t tensor_data_size = end - begin;
-
-        bool tensor_size_ok;
-        if (dtype == "F8_E4M3") {
-            tensor_storage.is_f8_e4m3 = true;
-            // f8 -> f16
-            tensor_size_ok = (tensor_storage.nbytes() == tensor_data_size * 2);
-        } else if (dtype == "F8_E5M2") {
-            tensor_storage.is_f8_e5m2 = true;
-            // f8 -> f16
-            tensor_size_ok = (tensor_storage.nbytes() == tensor_data_size * 2);
-        } else if (dtype == "F64") {
-            tensor_storage.is_f64 = true;
-            // f64 -> f32
-            tensor_size_ok = (tensor_storage.nbytes() * 2 == tensor_data_size);
-        } else if (dtype == "I64") {
-            tensor_storage.is_i64 = true;
-            // i64 -> i32
-            tensor_size_ok = (tensor_storage.nbytes() * 2 == tensor_data_size);
-        } else {
-            tensor_size_ok = (tensor_storage.nbytes() == tensor_data_size);
-        }
-        if (!tensor_size_ok) {
-            LOG_ERROR("size mismatch for tensor '%s' (%s)\n", name.c_str(), dtype.c_str());
-            return false;
+        if (!starts_with(tensor_storage.name, prefix)) {
+            tensor_storage.name = prefix + tensor_storage.name;
         }
+        tensor_storage.file_index = file_index;
 
         add_tensor_storage(tensor_storage);
 
-        // LOG_DEBUG("%s %s", tensor_storage.to_string().c_str(), dtype.c_str());
+        // LOG_DEBUG("%s", tensor_storage.to_string().c_str());
+    }
+
+    return true;
+}
+
+/*================================================= TorchLegacyModelLoader ==================================================*/
+
+bool ModelLoader::init_from_torch_legacy_file(const std::string& file_path, const std::string& prefix) {
+    LOG_DEBUG("init from torch legacy '%s'", file_path.c_str());
+
+    std::vector<TensorStorage> tensor_storages;
+    std::string error;
+    if (!read_torch_legacy_file(file_path, tensor_storages, &error)) {
+        if ((!error.empty()) && (ends_with(file_path, ".pt") || ends_with(file_path, ".pth"))) {
+            LOG_WARN("%s", error.c_str());
+        }
+        return false;
+    }
+
+    file_paths_.push_back(file_path);
+    size_t file_index = file_paths_.size() - 1;
+
+    for (auto& tensor_storage : tensor_storages) {
+        if (is_unused_tensor(tensor_storage.name)) {
+            continue;
+        }
+
+        if (!starts_with(tensor_storage.name, prefix)) {
+            tensor_storage.name = prefix + tensor_storage.name;
+        }
+        tensor_storage.file_index = file_index;
+
+        add_tensor_storage(tensor_storage);
+    }
+
+    return true;
+}
+
+/*================================================= TorchZipModelLoader ==================================================*/
+
+bool ModelLoader::init_from_torch_zip_file(const std::string& file_path, const std::string& prefix) {
+    LOG_DEBUG("init from '%s'", file_path.c_str());
+
+    std::vector<TensorStorage> tensor_storages;
+    std::string error;
+    if (!read_torch_zip_file(file_path, tensor_storages, &error)) {
+        LOG_ERROR("%s", error.c_str());
+        return false;
+    }
+
+    file_paths_.push_back(file_path);
+    size_t file_index = file_paths_.size() - 1;
+
+    for (auto& tensor_storage : tensor_storages) {
+        if (!starts_with(tensor_storage.name, prefix)) {
+            tensor_storage.name = prefix + tensor_storage.name;
+        }
+        tensor_storage.file_index = file_index;
+
+        add_tensor_storage(tensor_storage);
+
+        // LOG_DEBUG("%s", tensor_storage.to_string().c_str());
     }
 
     return true;
@@ -642,367 +422,6 @@ bool ModelLoader::init_from_diffusers_file(const std::string& file_path, const s
     return true;
 }
 
-/*================================================= CkptModelLoader ==================================================*/
-
-// $ python -m pickletools sd-v1-4/archive/data.pkl | head -n 100
-//     0: \x80 PROTO      2
-//     2: }    EMPTY_DICT
-//     3: q    BINPUT     0
-//     5: (    MARK
-//     6: X        BINUNICODE 'epoch'
-//    16: q        BINPUT     1
-//    18: K        BININT1    6
-//    20: X        BINUNICODE 'global_step'
-//    36: q        BINPUT     2
-//    38: J        BININT     470000
-//    43: X        BINUNICODE 'pytorch-lightning_version'
-//    73: q        BINPUT     3
-//    75: X        BINUNICODE '1.4.2'
-//    85: q        BINPUT     4
-//    87: X        BINUNICODE 'state_dict'
-//   102: q        BINPUT     5
-//   104: }        EMPTY_DICT
-//   105: q        BINPUT     6
-//   107: (        MARK
-//   108: X            BINUNICODE 'betas'
-//   118: q            BINPUT     7
-//   120: c            GLOBAL     'torch._utils _rebuild_tensor_v2'
-//   153: q            BINPUT     8
-//   155: (            MARK
-//   156: (                MARK
-//   157: X                    BINUNICODE 'storage'
-//   169: q                    BINPUT     9
-//   171: c                    GLOBAL     'torch FloatStorage'
-//   191: q                    BINPUT     10
-//   193: X                    BINUNICODE '0'
-//   199: q                    BINPUT     11
-//   201: X                    BINUNICODE 'cpu'
-//   209: q                    BINPUT     12
-//   211: M                    BININT2    1000
-//   214: t                    TUPLE      (MARK at 156)
-//   215: q                BINPUT     13
-//   217: Q                BINPERSID
-//   218: K                BININT1    0
-//   220: M                BININT2    1000
-//  ...............................
-//  3201: q            BINPUT     250
-//  3203: R            REDUCE
-//  3204: q            BINPUT     251
-//  3206: X            BINUNICODE 'model.diffusion_model.input_blocks.1.1.proj_in.weight'
-//  3264: q            BINPUT     252
-//  3266: h            BINGET     8
-//  3268: (            MARK
-//  3269: (                MARK
-//  3270: h                    BINGET     9
-//  3272: h                    BINGET     10
-//  3274: X                    BINUNICODE '30'
-//  3281: q                    BINPUT     253
-//  3283: h                    BINGET     12
-//  3285: J                    BININT     102400
-//  3290: t                    TUPLE      (MARK at 3269)
-//  3291: q                BINPUT     254
-//  3293: Q                BINPERSID
-//  3294: K                BININT1    0
-//  3296: (                MARK
-//  3297: M                    BININT2    320
-//  3300: M                    BININT2    320
-//  3303: K                    BININT1    1
-//  3305: K                    BININT1    1
-//  3307: t                    TUPLE      (MARK at 3296)
-//  3308: q                BINPUT     255
-//  3310: (                MARK
-//  3311: M                    BININT2    320
-//  3314: K                    BININT1    1
-//  3316: K                    BININT1    1
-//  3318: K                    BININT1    1
-//  3320: t                    TUPLE      (MARK at 3310)
-//  3321: r                LONG_BINPUT 256
-//  3326: \x89             NEWFALSE
-//  3327: h                BINGET     16
-//  3329: )                EMPTY_TUPLE
-//  3330: R                REDUCE
-//  3331: r                LONG_BINPUT 257
-//  3336: t                TUPLE      (MARK at 3268)
-//  3337: r            LONG_BINPUT 258
-//  3342: R            REDUCE
-//  3343: r            LONG_BINPUT 259
-//  3348: X            BINUNICODE 'model.diffusion_model.input_blocks.1.1.proj_in.bias'
-//  3404: r            LONG_BINPUT 260
-//  3409: h            BINGET     8
-//  3411: (            MARK
-//  3412: (                MARK
-//  3413: h                    BINGET     9
-//  3415: h                    BINGET     10
-//  3417: X                    BINUNICODE '31'
-
-struct PickleTensorReader {
-    enum ReadPhase {
-        READ_NAME,
-        READ_DATA,
-        CHECK_SIZE,
-        READ_DIMENS
-    };
-    ReadPhase phase   = READ_NAME;
-    size_t entry_size = 0;
-    int32_t nelements = 0;
-
-    TensorStorage tensor_storage;
-
-    static ggml_type global_type;  // all pickle_tensors data type
-    static bool read_global_type;
-
-    bool read_int_value(uint32_t value) {
-        if (phase == CHECK_SIZE) {
-            if (entry_size == value * ggml_type_size(tensor_storage.type)) {
-                nelements = value;
-                phase     = READ_DIMENS;
-                return true;
-            } else {
-                phase = READ_NAME;
-            }
-        } else if (phase == READ_DIMENS) {
-            if (tensor_storage.n_dims + 1 > SD_MAX_DIMS) {  // too many dimens
-                phase                 = READ_NAME;
-                tensor_storage.n_dims = 0;
-            }
-            if (nelements % value == 0) {
-                tensor_storage.ne[tensor_storage.n_dims] = value;
-                tensor_storage.n_dims++;
-            }
-        }
-        return false;
-    }
-
-    void read_global(const std::string& str) {
-        if (str == "FloatStorage") {
-            if (read_global_type) {
-                global_type      = GGML_TYPE_F32;
-                read_global_type = false;
-            }
-            tensor_storage.type = GGML_TYPE_F32;
-        } else if (str == "HalfStorage") {
-            if (read_global_type) {
-                global_type      = GGML_TYPE_F16;
-                read_global_type = false;
-            }
-            tensor_storage.type = GGML_TYPE_F16;
-        }
-    }
-
-    void read_string(const std::string& str, zip_t* zip, std::string dir) {
-        if (str == "storage") {
-            read_global_type = true;
-        } else if (str != "state_dict") {
-            if (phase == READ_DATA) {
-                std::string entry_name = dir + "data/" + std::string(str);
-
-                size_t i, n = zip_entries_total(zip);
-                for (i = 0; i < n; ++i) {
-                    zip_entry_openbyindex(zip, i);
-                    {
-                        std::string name = zip_entry_name(zip);
-                        if (name == entry_name) {
-                            tensor_storage.index_in_zip = (int)i;
-                            entry_size                  = zip_entry_size(zip);
-                            zip_entry_close(zip);
-                            break;
-                        }
-                    }
-                    zip_entry_close(zip);
-                }
-
-                phase = entry_size > 0 ? CHECK_SIZE : READ_NAME;
-            }
-            if (!read_global_type && phase == READ_NAME) {
-                tensor_storage.name = str;
-                phase               = READ_DATA;
-                tensor_storage.type = global_type;
-            }
-        }
-    }
-};
-
-ggml_type PickleTensorReader::global_type = GGML_TYPE_F32;  // all pickle_tensors data type
-bool PickleTensorReader::read_global_type = false;
-
-int find_char(uint8_t* buffer, int len, char c) {
-    for (int pos = 0; pos < len; pos++) {
-        if (buffer[pos] == c) {
-            return pos;
-        }
-    }
-    return -1;
-}
-
-#define MAX_STRING_BUFFER 512
-
-bool ModelLoader::parse_data_pkl(uint8_t* buffer,
-                                 size_t buffer_size,
-                                 zip_t* zip,
-                                 std::string dir,
-                                 size_t file_index,
-                                 const std::string prefix) {
-    uint8_t* buffer_end = buffer + buffer_size;
-    if (buffer[0] == 0x80) {  // proto
-        if (buffer[1] != 2) {
-            LOG_ERROR("Unsupported protocol\n");
-            return false;
-        }
-        buffer += 2;  // 0x80 and version
-        char string_buffer[MAX_STRING_BUFFER];
-        bool finish = false;
-        PickleTensorReader reader;
-        // read pickle binary file
-        while (!finish && buffer < buffer_end) {
-            uint8_t opcode = *buffer;
-            buffer++;
-            // https://github.com/python/cpython/blob/3.7/Lib/pickletools.py#L1048
-            // https://github.com/python/cpython/blob/main/Lib/pickle.py#L105
-            switch (opcode) {
-                case '}':  // EMPTY_DICT     = b'}'   # push empty dict
-                    break;
-                case ']':  // EMPTY_LIST     = b']'   # push empty list
-                    break;
-                // skip unused sections
-                case 'h':  // BINGET         = b'h'   #   "    "    "    "   "   "  ;   "    " 1-byte arg
-                case 'q':  // BINPUT         = b'q'   #   "     "    "   "   " ;   "    " 1-byte arg
-                case 'Q':  // BINPERSID      = b'Q'   #  "       "         "  ;  "  "   "     "  stack
-                    buffer++;
-                    break;
-                case 'r':  // LONG_BINPUT    = b'r'   #   "     "    "   "   " ;   "    " 4-byte arg
-                    buffer += 4;
-                    break;
-                case 0x95:  // FRAME            = b'\x95'  # indicate the beginning of a new frame
-                    buffer += 8;
-                    break;
-                case 0x94:  // MEMOIZE          = b'\x94'  # store top of the stack in memo
-                    break;
-                case '(':  // MARK           = b'('   # push special markobject on stack
-                    break;
-                case 'K':  // BININT1        = b'K'   # push 1-byte unsigned int
-                {
-                    uint8_t value = *buffer;
-                    if (reader.read_int_value(value)) {
-                        buffer++;
-                    }
-                    buffer++;
-                } break;
-                case 'M':  // BININT2        = b'M'   # push 2-byte unsigned int
-                {
-                    uint16_t value = read_short(buffer);
-                    if (reader.read_int_value(value)) {
-                        buffer++;
-                    }
-                    buffer += 2;
-                } break;
-                case 'J':  // BININT         = b'J'   # push four-byte signed int
-                {
-                    const int32_t value = read_int(buffer);
-                    if (reader.read_int_value(value)) {
-                        buffer++;  // skip tuple after read num_elements
-                    }
-                    buffer += 4;
-                } break;
-                case 'X':  // BINUNICODE     = b'X'   #   "     "       "  ; counted UTF-8 string argument
-                {
-                    const int32_t len = read_int(buffer);
-                    buffer += 4;
-                    memset(string_buffer, 0, MAX_STRING_BUFFER);
-                    if (len > MAX_STRING_BUFFER) {
-                        LOG_WARN("tensor name very large");
-                    }
-                    memcpy(string_buffer, buffer, len < MAX_STRING_BUFFER ? len : (MAX_STRING_BUFFER - 1));
-                    buffer += len;
-                    reader.read_string(string_buffer, zip, dir);
-                } break;
-                case 0x8C:  // SHORT_BINUNICODE = b'\x8c'  # push short string; UTF-8 length < 256 bytes
-                {
-                    const int8_t len = *buffer;
-                    buffer++;
-                    memset(string_buffer, 0, MAX_STRING_BUFFER);
-                    memcpy(string_buffer, buffer, len);
-                    buffer += len;
-                    // printf("String: '%s'\n", string_buffer);
-                } break;
-                case 'c':  // GLOBAL         = b'c'   # push self.find_class(modname, name); 2 string args
-                {
-                    int len = find_char(buffer, MAX_STRING_BUFFER, '\n');
-
-                    buffer += len + 1;
-                    len = find_char(buffer, MAX_STRING_BUFFER, '\n');
-
-                    memset(string_buffer, 0, MAX_STRING_BUFFER);
-                    memcpy(string_buffer, buffer, len);
-                    buffer += len + 1;
-                    reader.read_global(string_buffer);
-                } break;
-                case 0x86:  // TUPLE2         = b'\x86'  # build 2-tuple from two topmost stack items
-                case 0x85:  // TUPLE1         = b'\x85'  # build 1-tuple from stack top
-                case 't':   // TUPLE          = b't'   # build tuple from topmost stack items
-                    if (reader.phase == PickleTensorReader::READ_DIMENS) {
-                        reader.tensor_storage.reverse_ne();
-                        reader.tensor_storage.file_index = file_index;
-                        // if(strcmp(prefix.c_str(), "scarlett") == 0)
-                        // printf(" ZIP got tensor %s \n ", reader.tensor_storage.name.c_str());
-                        std::string name = reader.tensor_storage.name;
-                        if (!starts_with(name, prefix)) {
-                            name = prefix + name;
-                        }
-                        reader.tensor_storage.name = name;
-                        add_tensor_storage(reader.tensor_storage);
-
-                        // LOG_DEBUG("%s", reader.tensor_storage.name.c_str());
-                        // reset
-                        reader = PickleTensorReader();
-                    }
-                    break;
-                case '.':  // STOP           = b'.'   # every pickle ends with STOP
-                    finish = true;
-                    break;
-                default:
-                    break;
-            }
-        }
-    }
-    return true;
-}
-
-bool ModelLoader::init_from_ckpt_file(const std::string& file_path, const std::string& prefix) {
-    LOG_DEBUG("init from '%s'", file_path.c_str());
-    file_paths_.push_back(file_path);
-    size_t file_index = file_paths_.size() - 1;
-
-    zip_t* zip = zip_open(file_path.c_str(), 0, 'r');
-    if (zip == nullptr) {
-        LOG_ERROR("failed to open '%s'", file_path.c_str());
-        return false;
-    }
-    int n = (int)zip_entries_total(zip);
-    for (int i = 0; i < n; ++i) {
-        zip_entry_openbyindex(zip, i);
-        {
-            std::string name = zip_entry_name(zip);
-            size_t pos       = name.find("data.pkl");
-            if (pos != std::string::npos) {
-                std::string dir = name.substr(0, pos);
-                printf("ZIP %d, name = %s, dir = %s \n", i, name.c_str(), dir.c_str());
-                void* pkl_data = nullptr;
-                size_t pkl_size;
-                zip_entry_read(zip, &pkl_data, &pkl_size);
-
-                // LOG_DEBUG("%lld", pkl_size);
-
-                parse_data_pkl((uint8_t*)pkl_data, pkl_size, zip, dir, file_index, prefix);
-
-                free(pkl_data);
-            }
-        }
-        zip_entry_close(zip);
-    }
-    zip_close(zip);
-    return true;
-}
-
 SDVersion ModelLoader::get_sd_version() {
     TensorStorage token_embedding_weight, input_block_weight;
 
@@ -1268,8 +687,8 @@ std::map<ggml_type, uint32_t> ModelLoader::get_vae_wtype_stat() {
     return wtype_stat;
 }
 
-static std::vector<std::pair<std::string, ggml_type>> parse_tensor_type_rules(const std::string& tensor_type_rules) {
-    std::vector<std::pair<std::string, ggml_type>> result;
+TensorTypeRules parse_tensor_type_rules(const std::string& tensor_type_rules) {
+    TensorTypeRules result;
     for (const auto& item : split_string(tensor_type_rules, ',')) {
         if (item.size() == 0)
             continue;
@@ -1702,76 +1121,6 @@ bool ModelLoader::tensor_should_be_converted(const TensorStorage& tensor_storage
     return false;
 }
 
-bool ModelLoader::save_to_gguf_file(const std::string& file_path, ggml_type type, const std::string& tensor_type_rules_str) {
-    auto backend    = ggml_backend_cpu_init();
-    size_t mem_size = 1 * 1024 * 1024;  // for padding
-    mem_size += tensor_storage_map.size() * ggml_tensor_overhead();
-    mem_size += get_params_mem_size(backend, type);
-    LOG_INFO("model tensors mem size: %.2fMB", mem_size / 1024.f / 1024.f);
-    ggml_context* ggml_ctx = ggml_init({mem_size, nullptr, false});
-
-    gguf_context* gguf_ctx = gguf_init_empty();
-
-    auto tensor_type_rules = parse_tensor_type_rules(tensor_type_rules_str);
-
-    std::mutex tensor_mutex;
-    auto on_new_tensor_cb = [&](const TensorStorage& tensor_storage, ggml_tensor** dst_tensor) -> bool {
-        const std::string& name = tensor_storage.name;
-        ggml_type tensor_type   = tensor_storage.type;
-        ggml_type dst_type      = type;
-
-        for (const auto& tensor_type_rule : tensor_type_rules) {
-            std::regex pattern(tensor_type_rule.first);
-            if (std::regex_search(name, pattern)) {
-                dst_type = tensor_type_rule.second;
-                break;
-            }
-        }
-
-        if (tensor_should_be_converted(tensor_storage, dst_type)) {
-            tensor_type = dst_type;
-        }
-
-        std::lock_guard<std::mutex> lock(tensor_mutex);
-        ggml_tensor* tensor = ggml_new_tensor(ggml_ctx, tensor_type, tensor_storage.n_dims, tensor_storage.ne);
-        if (tensor == nullptr) {
-            LOG_ERROR("ggml_new_tensor failed");
-            return false;
-        }
-        ggml_set_name(tensor, name.c_str());
-
-        // LOG_DEBUG("%s %d %s %d[%d %d %d %d] %d[%d %d %d %d]", name.c_str(),
-        // ggml_nbytes(tensor), ggml_type_name(tensor_type),
-        // tensor_storage.n_dims,
-        // tensor_storage.ne[0], tensor_storage.ne[1], tensor_storage.ne[2], tensor_storage.ne[3],
-        // tensor->n_dims, tensor->ne[0], tensor->ne[1], tensor->ne[2], tensor->ne[3]);
-
-        if (!tensor->data) {
-            GGML_ASSERT(ggml_nelements(tensor) == 0);
-            // avoid crashing the gguf writer by setting a dummy pointer for zero-sized tensors
-            LOG_DEBUG("setting dummy pointer for zero-sized tensor %s", name.c_str());
-            tensor->data = ggml_get_mem_buffer(ggml_ctx);
-        }
-
-        *dst_tensor = tensor;
-
-        gguf_add_tensor(gguf_ctx, tensor);
-
-        return true;
-    };
-
-    bool success = load_tensors(on_new_tensor_cb);
-    ggml_backend_free(backend);
-    LOG_INFO("load tensors done");
-    LOG_INFO("trying to save tensors to %s", file_path.c_str());
-    if (success) {
-        gguf_write_to_file(gguf_ctx, file_path.c_str(), false);
-    }
-    ggml_free(ggml_ctx);
-    gguf_free(gguf_ctx);
-    return success;
-}
-
 int64_t ModelLoader::get_params_mem_size(ggml_backend_t backend, ggml_type type) {
     size_t alignment = 128;
     if (backend != nullptr) {
@@ -1791,29 +1140,3 @@ int64_t ModelLoader::get_params_mem_size(ggml_backend_t backend, ggml_type type)
 
     return mem_size;
 }
-
-bool convert(const char* input_path,
-             const char* vae_path,
-             const char* output_path,
-             sd_type_t output_type,
-             const char* tensor_type_rules,
-             bool convert_name) {
-    ModelLoader model_loader;
-
-    if (!model_loader.init_from_file(input_path)) {
-        LOG_ERROR("init model loader from file failed: '%s'", input_path);
-        return false;
-    }
-
-    if (vae_path != nullptr && strlen(vae_path) > 0) {
-        if (!model_loader.init_from_file(vae_path, "vae.")) {
-            LOG_ERROR("init model loader from file failed: '%s'", vae_path);
-            return false;
-        }
-    }
-    if (convert_name) {
-        model_loader.convert_tensors_name();
-    }
-    bool success = model_loader.save_to_gguf_file(output_path, (ggml_type)output_type, tensor_type_rules);
-    return success;
-}

src/model.h

@@ -5,20 +5,13 @@
 #include <map>
 #include <memory>
 #include <set>
-#include <sstream>
 #include <string>
-#include <tuple>
-#include <utility>
 #include <vector>
 
 #include "ggml-backend.h"
 #include "ggml.h"
-#include "gguf.h"
-#include "json.hpp"
+#include "model_io/tensor_storage.h"
 #include "ordered_map.hpp"
-#include "zip.h"
-
-#define SD_MAX_DIMS 5
 
 enum SDVersion {
     VERSION_SD1,
@@ -195,116 +188,10 @@ enum PMVersion {
     PM_VERSION_2,
 };
 
-struct TensorStorage {
-    std::string name;
-    ggml_type type          = GGML_TYPE_F32;
-    ggml_type expected_type = GGML_TYPE_COUNT;
-    bool is_f8_e4m3         = false;
-    bool is_f8_e5m2         = false;
-    bool is_f64             = false;
-    bool is_i64             = false;
-    int64_t ne[SD_MAX_DIMS] = {1, 1, 1, 1, 1};
-    int n_dims              = 0;
-
-    size_t file_index = 0;
-    int index_in_zip  = -1;  // >= means stored in a zip file
-    uint64_t offset   = 0;   // offset in file
-
-    TensorStorage() = default;
-
-    TensorStorage(std::string name, ggml_type type, const int64_t* ne, int n_dims, size_t file_index, size_t offset = 0)
-        : name(std::move(name)), type(type), n_dims(n_dims), file_index(file_index), offset(offset) {
-        for (int i = 0; i < n_dims; i++) {
-            this->ne[i] = ne[i];
-        }
-    }
-
-    int64_t nelements() const {
-        int64_t n = 1;
-        for (int i = 0; i < SD_MAX_DIMS; i++) {
-            n *= ne[i];
-        }
-        return n;
-    }
-
-    int64_t nbytes() const {
-        return nelements() * ggml_type_size(type) / ggml_blck_size(type);
-    }
-
-    int64_t nbytes_to_read() const {
-        if (is_f8_e4m3 || is_f8_e5m2) {
-            return nbytes() / 2;
-        } else if (is_f64 || is_i64) {
-            return nbytes() * 2;
-        } else {
-            return nbytes();
-        }
-    }
-
-    void unsqueeze() {
-        if (n_dims == 2) {
-            n_dims = 4;
-            ne[3]  = ne[1];
-            ne[2]  = ne[0];
-            ne[1]  = 1;
-            ne[0]  = 1;
-        }
-    }
-
-    std::vector<TensorStorage> chunk(size_t n) {
-        std::vector<TensorStorage> chunks;
-        uint64_t chunk_size = nbytes_to_read() / n;
-        // printf("%d/%d\n", chunk_size, nbytes_to_read());
-        reverse_ne();
-        for (size_t i = 0; i < n; i++) {
-            TensorStorage chunk_i = *this;
-            chunk_i.ne[0]         = ne[0] / n;
-            chunk_i.offset        = offset + i * chunk_size;
-            chunk_i.reverse_ne();
-            chunks.push_back(chunk_i);
-        }
-        reverse_ne();
-        return chunks;
-    }
-
-    void reverse_ne() {
-        int64_t new_ne[SD_MAX_DIMS] = {1, 1, 1, 1, 1};
-        for (int i = 0; i < n_dims; i++) {
-            new_ne[i] = ne[n_dims - 1 - i];
-        }
-        for (int i = 0; i < n_dims; i++) {
-            ne[i] = new_ne[i];
-        }
-    }
-
-    std::string to_string() const {
-        std::stringstream ss;
-        const char* type_name = ggml_type_name(type);
-        if (is_f8_e4m3) {
-            type_name = "f8_e4m3";
-        } else if (is_f8_e5m2) {
-            type_name = "f8_e5m2";
-        } else if (is_f64) {
-            type_name = "f64";
-        } else if (is_i64) {
-            type_name = "i64";
-        }
-        ss << name << " | " << type_name << " | ";
-        ss << n_dims << " [";
-        for (int i = 0; i < SD_MAX_DIMS; i++) {
-            ss << ne[i];
-            if (i != SD_MAX_DIMS - 1) {
-                ss << ", ";
-            }
-        }
-        ss << "]";
-        return ss.str();
-    }
-};
-
-typedef std::function<bool(const TensorStorage&, ggml_tensor**)> on_new_tensor_cb_t;
-
 typedef OrderedMap<std::string, TensorStorage> String2TensorStorage;
+using TensorTypeRules = std::vector<std::pair<std::string, ggml_type>>;
+
+TensorTypeRules parse_tensor_type_rules(const std::string& tensor_type_rules);
 
 class ModelLoader {
 protected:
@@ -314,16 +201,10 @@ protected:
 
     void add_tensor_storage(const TensorStorage& tensor_storage);
 
-    bool parse_data_pkl(uint8_t* buffer,
-                        size_t buffer_size,
-                        zip_t* zip,
-                        std::string dir,
-                        size_t file_index,
-                        const std::string prefix);
-
     bool init_from_gguf_file(const std::string& file_path, const std::string& prefix = "");
     bool init_from_safetensors_file(const std::string& file_path, const std::string& prefix = "");
-    bool init_from_ckpt_file(const std::string& file_path, const std::string& prefix = "");
+    bool init_from_torch_zip_file(const std::string& file_path, const std::string& prefix = "");
+    bool init_from_torch_legacy_file(const std::string& file_path, const std::string& prefix = "");
     bool init_from_diffusers_file(const std::string& file_path, const std::string& prefix = "");
 
 public:
@@ -353,7 +234,6 @@ public:
         return names;
     }
 
-    bool save_to_gguf_file(const std::string& file_path, ggml_type type, const std::string& tensor_type_rules);
     bool tensor_should_be_converted(const TensorStorage& tensor_storage, ggml_type type);
     int64_t get_params_mem_size(ggml_backend_t backend, ggml_type type = GGML_TYPE_COUNT);
     ~ModelLoader() = default;

src/model_io/binary_io.h

@@ -0,0 +1,57 @@
+#ifndef __SD_MODEL_IO_BINARY_IO_H__
+#define __SD_MODEL_IO_BINARY_IO_H__
+
+#include <cstdint>
+#include <ostream>
+
+namespace model_io {
+
+    inline int32_t read_int(const uint8_t* buffer) {
+        uint32_t value = 0;
+        value |= static_cast<uint32_t>(buffer[3]) << 24;
+        value |= static_cast<uint32_t>(buffer[2]) << 16;
+        value |= static_cast<uint32_t>(buffer[1]) << 8;
+        value |= static_cast<uint32_t>(buffer[0]);
+        return static_cast<int32_t>(value);
+    }
+
+    inline uint16_t read_short(const uint8_t* buffer) {
+        uint16_t value = 0;
+        value |= static_cast<uint16_t>(buffer[1]) << 8;
+        value |= static_cast<uint16_t>(buffer[0]);
+        return value;
+    }
+
+    inline uint64_t read_u64(const uint8_t* buffer) {
+        uint64_t value = 0;
+        value |= static_cast<uint64_t>(buffer[7]) << 56;
+        value |= static_cast<uint64_t>(buffer[6]) << 48;
+        value |= static_cast<uint64_t>(buffer[5]) << 40;
+        value |= static_cast<uint64_t>(buffer[4]) << 32;
+        value |= static_cast<uint64_t>(buffer[3]) << 24;
+        value |= static_cast<uint64_t>(buffer[2]) << 16;
+        value |= static_cast<uint64_t>(buffer[1]) << 8;
+        value |= static_cast<uint64_t>(buffer[0]);
+        return value;
+    }
+
+    inline void write_u64(std::ostream& stream, uint64_t value) {
+        uint8_t buffer[8];
+        for (int i = 0; i < 8; ++i) {
+            buffer[i] = static_cast<uint8_t>((value >> (8 * i)) & 0xFF);
+        }
+        stream.write((const char*)buffer, sizeof(buffer));
+    }
+
+    inline int find_char(const uint8_t* buffer, int len, char c) {
+        for (int pos = 0; pos < len; pos++) {
+            if (buffer[pos] == (uint8_t)c) {
+                return pos;
+            }
+        }
+        return -1;
+    }
+
+}  // namespace model_io
+
+#endif  // __SD_MODEL_IO_BINARY_IO_H__

src/model_io/gguf_io.cpp

@@ -0,0 +1,123 @@
+#include "gguf_io.h"
+
+#include <cstdint>
+#include <fstream>
+#include <string>
+#include <vector>
+
+#include "gguf.h"
+#include "gguf_reader_ext.h"
+#include "util.h"
+
+static void set_error(std::string* error, const std::string& message) {
+    if (error != nullptr) {
+        *error = message;
+    }
+}
+
+bool is_gguf_file(const std::string& file_path) {
+    std::ifstream file(file_path, std::ios::binary);
+    if (!file.is_open()) {
+        return false;
+    }
+
+    char magic[4];
+
+    file.read(magic, sizeof(magic));
+    if (!file) {
+        return false;
+    }
+    for (uint32_t i = 0; i < sizeof(magic); i++) {
+        if (magic[i] != GGUF_MAGIC[i]) {
+            return false;
+        }
+    }
+
+    return true;
+}
+
+bool read_gguf_file(const std::string& file_path,
+                    std::vector<TensorStorage>& tensor_storages,
+                    std::string* error) {
+    tensor_storages.clear();
+
+    gguf_context* ctx_gguf_ = nullptr;
+    ggml_context* ctx_meta_ = nullptr;
+
+    ctx_gguf_ = gguf_init_from_file(file_path.c_str(), {true, &ctx_meta_});
+    if (!ctx_gguf_) {
+        GGUFReader gguf_reader;
+        if (!gguf_reader.load(file_path)) {
+            set_error(error, "failed to open '" + file_path + "' with GGUFReader");
+            return false;
+        }
+
+        size_t data_offset = gguf_reader.data_offset();
+        for (const auto& gguf_tensor_info : gguf_reader.tensors()) {
+            TensorStorage tensor_storage(
+                gguf_tensor_info.name,
+                gguf_tensor_info.type,
+                gguf_tensor_info.shape.data(),
+                static_cast<int>(gguf_tensor_info.shape.size()),
+                0,
+                data_offset + gguf_tensor_info.offset);
+
+            tensor_storages.push_back(tensor_storage);
+        }
+
+        return true;
+    }
+
+    int n_tensors = static_cast<int>(gguf_get_n_tensors(ctx_gguf_));
+
+    size_t data_offset = gguf_get_data_offset(ctx_gguf_);
+    for (int i = 0; i < n_tensors; i++) {
+        std::string name   = gguf_get_tensor_name(ctx_gguf_, i);
+        ggml_tensor* dummy = ggml_get_tensor(ctx_meta_, name.c_str());
+        size_t offset      = data_offset + gguf_get_tensor_offset(ctx_gguf_, i);
+
+        TensorStorage tensor_storage(name, dummy->type, dummy->ne, ggml_n_dims(dummy), 0, offset);
+
+        if (ggml_nbytes(dummy) != tensor_storage.nbytes()) {
+            gguf_free(ctx_gguf_);
+            ggml_free(ctx_meta_);
+            set_error(error, "size mismatch for tensor '" + name + "'");
+            return false;
+        }
+
+        tensor_storages.push_back(tensor_storage);
+    }
+
+    gguf_free(ctx_gguf_);
+    ggml_free(ctx_meta_);
+
+    return true;
+}
+
+bool write_gguf_file(const std::string& file_path,
+                     const std::vector<TensorWriteInfo>& tensors,
+                     std::string* error) {
+    gguf_context* gguf_ctx = gguf_init_empty();
+    if (gguf_ctx == nullptr) {
+        set_error(error, "gguf_init_empty failed");
+        return false;
+    }
+
+    for (const TensorWriteInfo& write_tensor : tensors) {
+        ggml_tensor* tensor = write_tensor.tensor;
+        if (tensor == nullptr) {
+            set_error(error, "null tensor cannot be written to GGUF");
+            gguf_free(gguf_ctx);
+            return false;
+        }
+        gguf_add_tensor(gguf_ctx, tensor);
+    }
+
+    LOG_INFO("trying to save tensors to %s", file_path.c_str());
+    bool success = gguf_write_to_file(gguf_ctx, file_path.c_str(), false);
+    if (!success) {
+        set_error(error, "failed to write GGUF file '" + file_path + "'");
+    }
+    gguf_free(gguf_ctx);
+    return success;
+}

src/model_io/gguf_io.h

@@ -0,0 +1,17 @@
+#ifndef __SD_MODEL_IO_GGUF_IO_H__
+#define __SD_MODEL_IO_GGUF_IO_H__
+
+#include <string>
+#include <vector>
+
+#include "tensor_storage.h"
+
+bool is_gguf_file(const std::string& file_path);
+bool read_gguf_file(const std::string& file_path,
+                    std::vector<TensorStorage>& tensor_storages,
+                    std::string* error = nullptr);
+bool write_gguf_file(const std::string& file_path,
+                     const std::vector<TensorWriteInfo>& tensors,
+                     std::string* error = nullptr);
+
+#endif  // __SD_MODEL_IO_GGUF_IO_H__

src/model_io/gguf_reader_ext.h

@@ -1,5 +1,5 @@
-#ifndef __GGUF_READER_HPP__
-#define __GGUF_READER_HPP__
+#ifndef __SD_MODEL_IO_GGUF_READER_EXT_H__
+#define __SD_MODEL_IO_GGUF_READER_EXT_H__
 
 #include <cstdint>
 #include <fstream>
@@ -231,4 +231,4 @@ public:
     size_t data_offset() const { return data_offset_; }
 };
 
-#endif  // __GGUF_READER_HPP__
+#endif  // __SD_MODEL_IO_GGUF_READER_EXT_H__

src/model_io/pickle_io.h

@@ -0,0 +1,21 @@
+#ifndef __SD_MODEL_IO_PICKLE_IO_H__
+#define __SD_MODEL_IO_PICKLE_IO_H__
+
+#include <cstddef>
+#include <cstdint>
+#include <string>
+#include <unordered_map>
+#include <vector>
+
+#include "tensor_storage.h"
+
+bool skip_pickle_object(const uint8_t* buffer, size_t buffer_size, size_t* object_size);
+bool pickle_object_is_torch_magic_number(const uint8_t* buffer, size_t buffer_size);
+bool parse_pickle_uint32_object(const uint8_t* buffer, size_t buffer_size, uint32_t* value);
+bool parse_torch_state_dict_pickle(const uint8_t* buffer,
+                                   size_t buffer_size,
+                                   std::vector<TensorStorage>& tensor_storages,
+                                   std::unordered_map<std::string, uint64_t>& storage_nbytes,
+                                   std::string* error = nullptr);
+
+#endif  // __SD_MODEL_IO_PICKLE_IO_H__

src/model_io/safetensors_io.cpp

@@ -0,0 +1,316 @@
+#include "safetensors_io.h"
+
+#include <cstdint>
+#include <exception>
+#include <fstream>
+#include <string>
+#include <vector>
+
+#include "binary_io.h"
+#include "json.hpp"
+#include "util.h"
+
+static constexpr size_t ST_HEADER_SIZE_LEN = 8;
+
+static void set_error(std::string* error, const std::string& message) {
+    if (error != nullptr) {
+        *error = message;
+    }
+}
+
+bool is_safetensors_file(const std::string& file_path) {
+    std::ifstream file(file_path, std::ios::binary);
+    if (!file.is_open()) {
+        return false;
+    }
+
+    // get file size
+    file.seekg(0, file.end);
+    size_t file_size_ = file.tellg();
+    file.seekg(0, file.beg);
+
+    // read header size
+    if (file_size_ <= ST_HEADER_SIZE_LEN) {
+        return false;
+    }
+
+    uint8_t header_size_buf[ST_HEADER_SIZE_LEN];
+    file.read((char*)header_size_buf, ST_HEADER_SIZE_LEN);
+    if (!file) {
+        return false;
+    }
+
+    size_t header_size_ = model_io::read_u64(header_size_buf);
+    if (header_size_ >= file_size_ || header_size_ <= 2) {
+        return false;
+    }
+
+    // read header
+    std::vector<char> header_buf;
+    header_buf.resize(header_size_ + 1);
+    header_buf[header_size_] = '\0';
+    file.read(header_buf.data(), header_size_);
+    if (!file) {
+        return false;
+    }
+    try {
+        nlohmann::json header_ = nlohmann::json::parse(header_buf.data());
+    } catch (const std::exception&) {
+        return false;
+    }
+    return true;
+}
+
+static ggml_type safetensors_dtype_to_ggml_type(const std::string& dtype) {
+    ggml_type ttype = GGML_TYPE_COUNT;
+    if (dtype == "F16") {
+        ttype = GGML_TYPE_F16;
+    } else if (dtype == "BF16") {
+        ttype = GGML_TYPE_BF16;
+    } else if (dtype == "F32") {
+        ttype = GGML_TYPE_F32;
+    } else if (dtype == "F64") {
+        ttype = GGML_TYPE_F32;
+    } else if (dtype == "F8_E4M3") {
+        ttype = GGML_TYPE_F16;
+    } else if (dtype == "F8_E5M2") {
+        ttype = GGML_TYPE_F16;
+    } else if (dtype == "I32") {
+        ttype = GGML_TYPE_I32;
+    } else if (dtype == "I64") {
+        ttype = GGML_TYPE_I32;
+    }
+    return ttype;
+}
+
+// https://huggingface.co/docs/safetensors/index
+bool read_safetensors_file(const std::string& file_path,
+                           std::vector<TensorStorage>& tensor_storages,
+                           std::string* error) {
+    std::ifstream file(file_path, std::ios::binary);
+    if (!file.is_open()) {
+        set_error(error, "failed to open '" + file_path + "'");
+        return false;
+    }
+
+    // get file size
+    file.seekg(0, file.end);
+    size_t file_size_ = file.tellg();
+    file.seekg(0, file.beg);
+
+    // read header size
+    if (file_size_ <= ST_HEADER_SIZE_LEN) {
+        set_error(error, "invalid safetensor file '" + file_path + "'");
+        return false;
+    }
+
+    uint8_t header_size_buf[ST_HEADER_SIZE_LEN];
+    file.read((char*)header_size_buf, ST_HEADER_SIZE_LEN);
+    if (!file) {
+        set_error(error, "read safetensors header size failed: '" + file_path + "'");
+        return false;
+    }
+
+    size_t header_size_ = model_io::read_u64(header_size_buf);
+    if (header_size_ >= file_size_) {
+        set_error(error, "invalid safetensor file '" + file_path + "'");
+        return false;
+    }
+
+    // read header
+    std::vector<char> header_buf;
+    header_buf.resize(header_size_ + 1);
+    header_buf[header_size_] = '\0';
+    file.read(header_buf.data(), header_size_);
+    if (!file) {
+        set_error(error, "read safetensors header failed: '" + file_path + "'");
+        return false;
+    }
+
+    nlohmann::json header_;
+    try {
+        header_ = nlohmann::json::parse(header_buf.data());
+    } catch (const std::exception&) {
+        set_error(error, "parsing safetensors header failed: '" + file_path + "'");
+        return false;
+    }
+
+    tensor_storages.clear();
+    for (auto& item : header_.items()) {
+        std::string name           = item.key();
+        nlohmann::json tensor_info = item.value();
+        // LOG_DEBUG("%s %s\n", name.c_str(), tensor_info.dump().c_str());
+
+        if (name == "__metadata__") {
+            continue;
+        }
+
+        std::string dtype    = tensor_info["dtype"];
+        nlohmann::json shape = tensor_info["shape"];
+
+        if (dtype == "U8") {
+            continue;
+        }
+
+        size_t begin = tensor_info["data_offsets"][0].get<size_t>();
+        size_t end   = tensor_info["data_offsets"][1].get<size_t>();
+
+        ggml_type type = safetensors_dtype_to_ggml_type(dtype);
+        if (type == GGML_TYPE_COUNT) {
+            set_error(error, "unsupported dtype '" + dtype + "' (tensor '" + name + "')");
+            return false;
+        }
+
+        if (shape.size() > SD_MAX_DIMS) {
+            set_error(error, "invalid tensor '" + name + "'");
+            return false;
+        }
+
+        int n_dims              = (int)shape.size();
+        int64_t ne[SD_MAX_DIMS] = {1, 1, 1, 1, 1};
+        for (int i = 0; i < n_dims; i++) {
+            ne[i] = shape[i].get<int64_t>();
+        }
+
+        if (n_dims == 5) {
+            n_dims = 4;
+            ne[0]  = ne[0] * ne[1];
+            ne[1]  = ne[2];
+            ne[2]  = ne[3];
+            ne[3]  = ne[4];
+        }
+
+        // ggml_n_dims returns 1 for scalars
+        if (n_dims == 0) {
+            n_dims = 1;
+        }
+
+        TensorStorage tensor_storage(name, type, ne, n_dims, 0, ST_HEADER_SIZE_LEN + header_size_ + begin);
+        tensor_storage.reverse_ne();
+
+        size_t tensor_data_size = end - begin;
+
+        bool tensor_size_ok;
+        if (dtype == "F8_E4M3") {
+            tensor_storage.is_f8_e4m3 = true;
+            // f8 -> f16
+            tensor_size_ok = (tensor_storage.nbytes() == tensor_data_size * 2);
+        } else if (dtype == "F8_E5M2") {
+            tensor_storage.is_f8_e5m2 = true;
+            // f8 -> f16
+            tensor_size_ok = (tensor_storage.nbytes() == tensor_data_size * 2);
+        } else if (dtype == "F64") {
+            tensor_storage.is_f64 = true;
+            // f64 -> f32
+            tensor_size_ok = (tensor_storage.nbytes() * 2 == tensor_data_size);
+        } else if (dtype == "I64") {
+            tensor_storage.is_i64 = true;
+            // i64 -> i32
+            tensor_size_ok = (tensor_storage.nbytes() * 2 == tensor_data_size);
+        } else {
+            tensor_size_ok = (tensor_storage.nbytes() == tensor_data_size);
+        }
+        if (!tensor_size_ok) {
+            set_error(error, "size mismatch for tensor '" + name + "' (" + dtype + ")");
+            return false;
+        }
+
+        tensor_storages.push_back(tensor_storage);
+
+        // LOG_DEBUG("%s %s", tensor_storage.to_string().c_str(), dtype.c_str());
+    }
+
+    return true;
+}
+
+static bool ggml_type_to_safetensors_dtype(ggml_type type, std::string* dtype) {
+    switch (type) {
+        case GGML_TYPE_F16:
+            *dtype = "F16";
+            return true;
+        case GGML_TYPE_BF16:
+            *dtype = "BF16";
+            return true;
+        case GGML_TYPE_F32:
+            *dtype = "F32";
+            return true;
+        case GGML_TYPE_I32:
+            *dtype = "I32";
+            return true;
+        default:
+            return false;
+    }
+}
+
+bool write_safetensors_file(const std::string& file_path,
+                            const std::vector<TensorWriteInfo>& tensors,
+                            std::string* error) {
+    nlohmann::ordered_json header = nlohmann::ordered_json::object();
+
+    uint64_t data_offset = 0;
+    for (const TensorWriteInfo& write_tensor : tensors) {
+        ggml_tensor* tensor = write_tensor.tensor;
+        if (tensor == nullptr) {
+            set_error(error, "null tensor cannot be written to safetensors");
+            return false;
+        }
+
+        const std::string name = ggml_get_name(tensor);
+        std::string dtype;
+        if (!ggml_type_to_safetensors_dtype(tensor->type, &dtype)) {
+            set_error(error,
+                      "unsupported safetensors dtype '" + std::string(ggml_type_name(tensor->type)) +
+                          "' for tensor '" + name + "'");
+            return false;
+        }
+
+        const uint64_t tensor_nbytes = ggml_nbytes(tensor);
+
+        nlohmann::ordered_json json_tensor_info = nlohmann::ordered_json::object();
+        json_tensor_info["dtype"]               = dtype;
+
+        nlohmann::ordered_json shape = nlohmann::ordered_json::array();
+        for (int i = 0; i < write_tensor.n_dims; ++i) {
+            shape.push_back(write_tensor.ne[write_tensor.n_dims - 1 - i]);
+        }
+        json_tensor_info["shape"] = shape;
+
+        nlohmann::ordered_json data_offsets = nlohmann::ordered_json::array();
+        data_offsets.push_back(data_offset);
+        data_offsets.push_back(data_offset + tensor_nbytes);
+        json_tensor_info["data_offsets"] = data_offsets;
+
+        header[name] = json_tensor_info;
+        data_offset += tensor_nbytes;
+    }
+
+    const std::string header_str = header.dump();
+
+    std::ofstream file(file_path, std::ios::binary);
+    if (!file.is_open()) {
+        set_error(error, "failed to open '" + file_path + "' for writing");
+        return false;
+    }
+
+    LOG_INFO("trying to save tensors to %s", file_path.c_str());
+    model_io::write_u64(file, header_str.size());
+    file.write(header_str.data(), header_str.size());
+    if (!file) {
+        set_error(error, "failed to write safetensors header to '" + file_path + "'");
+        return false;
+    }
+
+    for (const TensorWriteInfo& write_tensor : tensors) {
+        ggml_tensor* tensor        = write_tensor.tensor;
+        const std::string name     = ggml_get_name(tensor);
+        const size_t tensor_nbytes = ggml_nbytes(tensor);
+        file.write((const char*)tensor->data, tensor_nbytes);
+        if (!file) {
+            set_error(error,
+                      "failed to write tensor '" + name + "' to '" + file_path + "'");
+            return false;
+        }
+    }
+
+    return true;
+}

src/model_io/safetensors_io.h

@@ -0,0 +1,17 @@
+#ifndef __SD_MODEL_IO_SAFETENSORS_IO_H__
+#define __SD_MODEL_IO_SAFETENSORS_IO_H__
+
+#include <string>
+#include <vector>
+
+#include "tensor_storage.h"
+
+bool is_safetensors_file(const std::string& file_path);
+bool read_safetensors_file(const std::string& file_path,
+                           std::vector<TensorStorage>& tensor_storages,
+                           std::string* error = nullptr);
+bool write_safetensors_file(const std::string& file_path,
+                            const std::vector<TensorWriteInfo>& tensors,
+                            std::string* error = nullptr);
+
+#endif  // __SD_MODEL_IO_SAFETENSORS_IO_H__

src/model_io/tensor_storage.h

@@ -0,0 +1,132 @@
+#ifndef __SD_TENSOR_STORAGE_H__
+#define __SD_TENSOR_STORAGE_H__
+
+#include <cstddef>
+#include <cstdint>
+#include <functional>
+#include <sstream>
+#include <string>
+#include <utility>
+#include <vector>
+
+#include "ggml.h"
+
+#define SD_MAX_DIMS 5
+
+struct TensorStorage {
+    std::string name;
+    ggml_type type          = GGML_TYPE_F32;
+    ggml_type expected_type = GGML_TYPE_COUNT;
+    bool is_f8_e4m3         = false;
+    bool is_f8_e5m2         = false;
+    bool is_f64             = false;
+    bool is_i64             = false;
+    int64_t ne[SD_MAX_DIMS] = {1, 1, 1, 1, 1};
+    int n_dims              = 0;
+
+    std::string storage_key;
+    size_t file_index = 0;
+    int index_in_zip  = -1;  // >= means stored in a zip file
+    uint64_t offset   = 0;   // offset in file
+
+    TensorStorage() = default;
+
+    TensorStorage(std::string name, ggml_type type, const int64_t* ne, int n_dims, size_t file_index, size_t offset = 0)
+        : name(std::move(name)), type(type), n_dims(n_dims), file_index(file_index), offset(offset) {
+        for (int i = 0; i < n_dims; i++) {
+            this->ne[i] = ne[i];
+        }
+    }
+
+    int64_t nelements() const {
+        int64_t n = 1;
+        for (int i = 0; i < SD_MAX_DIMS; i++) {
+            n *= ne[i];
+        }
+        return n;
+    }
+
+    int64_t nbytes() const {
+        return nelements() * ggml_type_size(type) / ggml_blck_size(type);
+    }
+
+    int64_t nbytes_to_read() const {
+        if (is_f8_e4m3 || is_f8_e5m2) {
+            return nbytes() / 2;
+        } else if (is_f64 || is_i64) {
+            return nbytes() * 2;
+        } else {
+            return nbytes();
+        }
+    }
+
+    void unsqueeze() {
+        if (n_dims == 2) {
+            n_dims = 4;
+            ne[3]  = ne[1];
+            ne[2]  = ne[0];
+            ne[1]  = 1;
+            ne[0]  = 1;
+        }
+    }
+
+    std::vector<TensorStorage> chunk(size_t n) {
+        std::vector<TensorStorage> chunks;
+        uint64_t chunk_size = nbytes_to_read() / n;
+        // printf("%d/%d\n", chunk_size, nbytes_to_read());
+        reverse_ne();
+        for (size_t i = 0; i < n; i++) {
+            TensorStorage chunk_i = *this;
+            chunk_i.ne[0]         = ne[0] / n;
+            chunk_i.offset        = offset + i * chunk_size;
+            chunk_i.reverse_ne();
+            chunks.push_back(chunk_i);
+        }
+        reverse_ne();
+        return chunks;
+    }
+
+    void reverse_ne() {
+        int64_t new_ne[SD_MAX_DIMS] = {1, 1, 1, 1, 1};
+        for (int i = 0; i < n_dims; i++) {
+            new_ne[i] = ne[n_dims - 1 - i];
+        }
+        for (int i = 0; i < n_dims; i++) {
+            ne[i] = new_ne[i];
+        }
+    }
+
+    std::string to_string() const {
+        std::stringstream ss;
+        const char* type_name = ggml_type_name(type);
+        if (is_f8_e4m3) {
+            type_name = "f8_e4m3";
+        } else if (is_f8_e5m2) {
+            type_name = "f8_e5m2";
+        } else if (is_f64) {
+            type_name = "f64";
+        } else if (is_i64) {
+            type_name = "i64";
+        }
+        ss << name << " | " << type_name << " | ";
+        ss << n_dims << " [";
+        for (int i = 0; i < SD_MAX_DIMS; i++) {
+            ss << ne[i];
+            if (i != SD_MAX_DIMS - 1) {
+                ss << ", ";
+            }
+        }
+        ss << "]";
+        return ss.str();
+    }
+};
+
+struct TensorWriteInfo {
+    int64_t ne[SD_MAX_DIMS] = {1, 1, 1, 1, 1};
+    int n_dims              = 0;
+    ggml_tensor* tensor     = nullptr;
+};
+
+typedef std::function<bool(const TensorStorage&, ggml_tensor**)> on_new_tensor_cb_t;
+
+#endif  // __SD_TENSOR_STORAGE_H__

src/model_io/torch_legacy_io.cpp

@@ -0,0 +1,252 @@
+#include "torch_legacy_io.h"
+
+#include <algorithm>
+#include <cstdint>
+#include <fstream>
+#include <string>
+#include <unordered_map>
+#include <vector>
+
+#include "pickle_io.h"
+#include "util.h"
+
+// torch.save format background:
+//
+//   - Before PyTorch 1.6.0, torch.save used this legacy non-zip format by
+//     default.
+//   - Since PyTorch 1.6.0, torch.save defaults to an uncompressed ZIP64 archive
+//     containing data.pkl, data/, version, and, since PyTorch 2.1.0, byteorder.
+//   - The old format can still be produced explicitly with:
+//       torch.save(obj, path, _use_new_zipfile_serialization=False)
+//
+// Whether obj is a state_dict or a whole nn.Module does not change the outer
+// container format selected by torch.save. It changes the pickled object inside:
+//
+//   - state_dict: usually an OrderedDict[str, Tensor]. pickle_io.cpp supports a
+//     restricted subset of this layout because tensor metadata and raw storages
+//     can be recovered without executing pickle callables.
+//   - whole module/checkpoint object: arbitrary Python object graph. This may
+//     require importing user classes and executing pickle GLOBAL/REDUCE rebuild
+//     logic, so it is intentionally not supported here.
+//
+// Legacy non-zip PyTorch files are not a single pickle object:
+//
+//   1. pickle object: PyTorch legacy magic number
+//   2. pickle object: legacy protocol version, expected to be 1001
+//   3. pickle object: sys_info metadata, ignored by this reader
+//   4. pickle object: state_dict metadata, parsed by pickle_io.cpp
+//   5. pickle object: serialized storage key list, skipped here
+//   6. raw storage data payloads
+//      - PyTorch writes storages after the pickles, ordered by storage key
+//      - each storage has an 8-byte legacy storage header followed by raw bytes
+static constexpr size_t LEGACY_STORAGE_HEADER_SIZE = 8;
+
+static void set_error(std::string* error, const std::string& message) {
+    if (error != nullptr) {
+        *error = message;
+    }
+}
+
+static std::string bytes_to_hex(const std::vector<uint8_t>& bytes) {
+    static const char* hex = "0123456789ABCDEF";
+    std::string result;
+    result.reserve(bytes.size() * 3);
+    for (size_t i = 0; i < bytes.size(); ++i) {
+        if (i > 0) {
+            result.push_back('-');
+        }
+        result.push_back(hex[(bytes[i] >> 4) & 0x0F]);
+        result.push_back(hex[bytes[i] & 0x0F]);
+    }
+    return result;
+}
+
+static bool is_probably_tar_file(const std::vector<uint8_t>& header) {
+    return header.size() >= 262 &&
+           header[257] == 'u' &&
+           header[258] == 's' &&
+           header[259] == 't' &&
+           header[260] == 'a' &&
+           header[261] == 'r';
+}
+
+static std::string torch_legacy_diagnostics(const std::string& file_path, const std::vector<uint8_t>& buffer) {
+    if (!ends_with(file_path, ".pt") && !ends_with(file_path, ".pth")) {
+        return "";
+    }
+    if (buffer.empty()) {
+        return "unsupported PyTorch file '" + file_path + "': empty file";
+    }
+
+    size_t short_len = std::min<size_t>(buffer.size(), 32);
+    std::vector<uint8_t> short_header(buffer.begin(), buffer.begin() + short_len);
+    const bool raw_pickle = buffer[0] == 0x80;
+    const bool tar_file   = is_probably_tar_file(buffer);
+
+    std::string message = "unsupported PyTorch file '" + file_path + "': first bytes " +
+                          bytes_to_hex(short_header) +
+                          ", raw_pickle=" + (raw_pickle ? "true" : "false") +
+                          ", tar=" + (tar_file ? "true" : "false");
+    if (raw_pickle) {
+        message += "; raw pickle did not match the restricted state_dict layouts currently supported";
+    } else if (tar_file) {
+        message += "; legacy tar PyTorch checkpoints are not supported yet";
+    }
+    return message;
+}
+
+bool read_torch_legacy_file(const std::string& file_path,
+                            std::vector<TensorStorage>& tensor_storages,
+                            std::string* error) {
+    std::ifstream file(file_path, std::ios::binary);
+    if (!file.is_open()) {
+        set_error(error, "failed to open '" + file_path + "'");
+        return false;
+    }
+
+    file.seekg(0, file.end);
+    size_t file_size = (size_t)file.tellg();
+    file.seekg(0, file.beg);
+    if (file_size == 0) {
+        set_error(error, "empty file '" + file_path + "'");
+        return false;
+    }
+
+    std::vector<uint8_t> buffer(file_size);
+    file.read((char*)buffer.data(), file_size);
+    if (!file) {
+        set_error(error, "failed to read '" + file_path + "'");
+        return false;
+    }
+
+    auto finalize_tensor_offsets = [&](size_t storage_data_offset,
+                                       const std::unordered_map<std::string, uint64_t>& legacy_storage_map) -> bool {
+        if (storage_data_offset > file_size) {
+            return false;
+        }
+
+        std::vector<std::string> storage_keys;
+        storage_keys.reserve(legacy_storage_map.size());
+        for (const auto& [storage_key, _] : legacy_storage_map) {
+            storage_keys.push_back(storage_key);
+        }
+        std::sort(storage_keys.begin(), storage_keys.end());
+
+        std::unordered_map<std::string, uint64_t> storage_offsets;
+        uint64_t current_offset = storage_data_offset;
+        for (const auto& storage_key : storage_keys) {
+            auto it = legacy_storage_map.find(storage_key);
+            if (it == legacy_storage_map.end()) {
+                return false;
+            }
+            if (current_offset + LEGACY_STORAGE_HEADER_SIZE + it->second > file_size) {
+                return false;
+            }
+            storage_offsets[storage_key] = current_offset + LEGACY_STORAGE_HEADER_SIZE;
+            current_offset += LEGACY_STORAGE_HEADER_SIZE + it->second;
+        }
+
+        for (auto& tensor_storage : tensor_storages) {
+            if (tensor_storage.storage_key.empty()) {
+                continue;
+            }
+
+            auto it_offset = storage_offsets.find(tensor_storage.storage_key);
+            auto it_size   = legacy_storage_map.find(tensor_storage.storage_key);
+            if (it_offset == storage_offsets.end() || it_size == legacy_storage_map.end()) {
+                return false;
+            }
+
+            uint64_t base_offset    = it_offset->second;
+            uint64_t storage_nbytes = it_size->second;
+            uint64_t tensor_nbytes  = tensor_storage.nbytes_to_read();
+            if (tensor_storage.offset + tensor_nbytes > storage_nbytes) {
+                return false;
+            }
+
+            tensor_storage.offset = base_offset + tensor_storage.offset;
+            tensor_storage.storage_key.clear();
+        }
+
+        return true;
+    };
+
+    auto parse_state_dict_at = [&](size_t state_dict_offset, size_t state_dict_size, size_t* storage_data_offset) -> bool {
+        tensor_storages.clear();
+        std::unordered_map<std::string, uint64_t> legacy_storage_map;
+        if (!parse_torch_state_dict_pickle(buffer.data() + state_dict_offset,
+                                           state_dict_size,
+                                           tensor_storages,
+                                           legacy_storage_map,
+                                           error)) {
+            return false;
+        }
+
+        size_t offset_after_state_dict = state_dict_offset + state_dict_size;
+        size_t storage_keys_size       = 0;
+        if (!skip_pickle_object(buffer.data() + offset_after_state_dict,
+                                buffer.size() - offset_after_state_dict,
+                                &storage_keys_size)) {
+            return false;
+        }
+
+        *storage_data_offset = offset_after_state_dict + storage_keys_size;
+        return finalize_tensor_offsets(*storage_data_offset, legacy_storage_map);
+    };
+
+    size_t object_size_1 = 0;
+    size_t offset        = 0;
+
+    if (skip_pickle_object(buffer.data(), buffer.size(), &object_size_1) &&
+        pickle_object_is_torch_magic_number(buffer.data(), object_size_1)) {
+        offset += object_size_1;
+
+        size_t object_size_2 = 0;
+        if (!skip_pickle_object(buffer.data() + offset, buffer.size() - offset, &object_size_2)) {
+            set_error(error, torch_legacy_diagnostics(file_path, buffer));
+            return false;
+        }
+        uint32_t protocol_version = 0;
+        if (!parse_pickle_uint32_object(buffer.data() + offset, object_size_2, &protocol_version) || protocol_version != 1001) {
+            set_error(error, torch_legacy_diagnostics(file_path, buffer));
+            return false;
+        }
+        offset += object_size_2;
+
+        size_t object_size_3 = 0;
+        if (!skip_pickle_object(buffer.data() + offset, buffer.size() - offset, &object_size_3)) {
+            set_error(error, torch_legacy_diagnostics(file_path, buffer));
+            return false;
+        }
+        offset += object_size_3;
+
+        size_t state_dict_size = 0;
+        if (!skip_pickle_object(buffer.data() + offset, buffer.size() - offset, &state_dict_size)) {
+            set_error(error, torch_legacy_diagnostics(file_path, buffer));
+            return false;
+        }
+
+        size_t storage_data_offset = 0;
+        if (parse_state_dict_at(offset, state_dict_size, &storage_data_offset)) {
+            return true;
+        }
+
+        if (error != nullptr && error->empty()) {
+            set_error(error, torch_legacy_diagnostics(file_path, buffer));
+        }
+        return false;
+    }
+
+    size_t state_dict_size = 0;
+    if (skip_pickle_object(buffer.data(), buffer.size(), &state_dict_size)) {
+        size_t storage_data_offset = 0;
+        if (parse_state_dict_at(0, state_dict_size, &storage_data_offset)) {
+            return true;
+        }
+    }
+
+    if (error != nullptr && error->empty()) {
+        set_error(error, torch_legacy_diagnostics(file_path, buffer));
+    }
+    return false;
+}

src/model_io/torch_legacy_io.h

@@ -0,0 +1,13 @@
+#ifndef __SD_MODEL_IO_TORCH_LEGACY_IO_H__
+#define __SD_MODEL_IO_TORCH_LEGACY_IO_H__
+
+#include <string>
+#include <vector>
+
+#include "tensor_storage.h"
+
+bool read_torch_legacy_file(const std::string& file_path,
+                            std::vector<TensorStorage>& tensor_storages,
+                            std::string* error = nullptr);
+
+#endif  // __SD_MODEL_IO_TORCH_LEGACY_IO_H__

src/model_io/torch_zip_io.cpp

@@ -0,0 +1,140 @@
+#include "torch_zip_io.h"
+
+#include <cstdint>
+#include <cstdlib>
+#include <string>
+#include <unordered_map>
+#include <vector>
+
+#include "pickle_io.h"
+
+#include "zip.h"
+
+static void set_error(std::string* error, const std::string& message) {
+    if (error != nullptr) {
+        *error = message;
+    }
+}
+
+bool is_torch_zip_file(const std::string& file_path) {
+    zip_t* zip = zip_open(file_path.c_str(), 0, 'r');
+    if (zip == nullptr) {
+        return false;
+    }
+    zip_close(zip);
+    return true;
+}
+
+static bool find_zip_entry(zip_t* zip, const std::string& entry_name, int* index, uint64_t* size) {
+    size_t n = zip_entries_total(zip);
+    for (size_t i = 0; i < n; ++i) {
+        zip_entry_openbyindex(zip, i);
+        std::string name = zip_entry_name(zip);
+        if (name == entry_name) {
+            *index = (int)i;
+            *size  = zip_entry_size(zip);
+            zip_entry_close(zip);
+            return true;
+        }
+        zip_entry_close(zip);
+    }
+    return false;
+}
+
+static bool parse_zip_data_pkl(const uint8_t* buffer,
+                               size_t buffer_size,
+                               zip_t* zip,
+                               const std::string& dir,
+                               std::vector<TensorStorage>& tensor_storages,
+                               std::string* error) {
+    std::vector<TensorStorage> parsed_tensors;
+    std::unordered_map<std::string, uint64_t> storage_nbytes;
+    if (!parse_torch_state_dict_pickle(buffer, buffer_size, parsed_tensors, storage_nbytes, error)) {
+        if (error != nullptr && error->empty()) {
+            *error = "failed to parse torch zip pickle metadata";
+        }
+        return false;
+    }
+
+    for (auto& tensor_storage : parsed_tensors) {
+        if (tensor_storage.storage_key.empty()) {
+            set_error(error, "tensor '" + tensor_storage.name + "' has no storage key");
+            return false;
+        }
+
+        const std::string entry_name = dir + "data/" + tensor_storage.storage_key;
+        int zip_index                = -1;
+        uint64_t entry_size          = 0;
+        if (!find_zip_entry(zip, entry_name, &zip_index, &entry_size)) {
+            set_error(error, "storage entry '" + entry_name + "' was not found");
+            return false;
+        }
+
+        auto it_storage_size = storage_nbytes.find(tensor_storage.storage_key);
+        if (it_storage_size != storage_nbytes.end() && entry_size < it_storage_size->second) {
+            set_error(error, "storage entry '" + entry_name + "' is smaller than pickle metadata");
+            return false;
+        }
+
+        uint64_t tensor_nbytes = tensor_storage.nbytes_to_read();
+        if (tensor_storage.offset + tensor_nbytes > entry_size) {
+            set_error(error, "tensor '" + tensor_storage.name + "' exceeds storage entry '" + entry_name + "'");
+            return false;
+        }
+
+        tensor_storage.index_in_zip = zip_index;
+        tensor_storage.storage_key.clear();
+        tensor_storages.push_back(tensor_storage);
+    }
+
+    return true;
+}
+
+bool read_torch_zip_file(const std::string& file_path,
+                         std::vector<TensorStorage>& tensor_storages,
+                         std::string* error) {
+    zip_t* zip = zip_open(file_path.c_str(), 0, 'r');
+    if (zip == nullptr) {
+        set_error(error, "failed to open '" + file_path + "'");
+        return false;
+    }
+
+    tensor_storages.clear();
+    bool success        = true;
+    bool found_data_pkl = false;
+    int n               = (int)zip_entries_total(zip);
+    for (int i = 0; i < n; ++i) {
+        zip_entry_openbyindex(zip, i);
+        std::string name = zip_entry_name(zip);
+        size_t pos       = name.find("data.pkl");
+        if (pos != std::string::npos) {
+            found_data_pkl  = true;
+            std::string dir = name.substr(0, pos);
+            void* pkl_data  = nullptr;
+            size_t pkl_size = 0;
+            zip_entry_read(zip, &pkl_data, &pkl_size);
+
+            if (pkl_data == nullptr || pkl_size == 0) {
+                set_error(error, "failed to read '" + name + "' from '" + file_path + "'");
+                success = false;
+            } else if (!parse_zip_data_pkl((const uint8_t*)pkl_data, pkl_size, zip, dir, tensor_storages, error)) {
+                success = false;
+            }
+
+            free(pkl_data);
+        }
+        zip_entry_close(zip);
+
+        if (!success) {
+            break;
+        }
+    }
+
+    if (success && !found_data_pkl) {
+        set_error(error, "data.pkl was not found in '" + file_path + "'");
+        success = false;
+    }
+
+    zip_close(zip);
+    return success;
+}

src/model_io/torch_zip_io.h

@@ -0,0 +1,14 @@
+#ifndef __SD_MODEL_IO_TORCH_ZIP_IO_H__
+#define __SD_MODEL_IO_TORCH_ZIP_IO_H__
+
+#include <string>
+#include <vector>
+
+#include "tensor_storage.h"
+
+bool is_torch_zip_file(const std::string& file_path);
+bool read_torch_zip_file(const std::string& file_path,
+                         std::vector<TensorStorage>& tensor_storages,
+                         std::string* error = nullptr);
+
+#endif  // __SD_MODEL_IO_TORCH_ZIP_IO_H__

src/stable-diffusion.cpp

@@ -17,6 +17,7 @@
 #include "pmid.hpp"
 #include "sample-cache.h"
 #include "tae.hpp"
+#include "upscaler.h"
 #include "vae.hpp"
 
 #include "latent-preview.h"
@@ -943,6 +944,8 @@ public:
                     pred_type = FLOW_PRED;
                     if (sd_version_is_wan(version)) {
                         default_flow_shift = 5.f;
+                    } else if (sd_version_is_ernie_image(version)) {
+                        default_flow_shift = 4.f;
                     } else {
                         default_flow_shift = 3.f;
                     }
@@ -2111,6 +2114,35 @@ enum lora_apply_mode_t str_to_lora_apply_mode(const char* str) {
     return LORA_APPLY_MODE_COUNT;
 }
 
+const char* hires_upscaler_to_str[] = {
+    "None",
+    "Latent",
+    "Latent (nearest)",
+    "Latent (nearest-exact)",
+    "Latent (antialiased)",
+    "Latent (bicubic)",
+    "Latent (bicubic antialiased)",
+    "Lanczos",
+    "Nearest",
+    "Model",
+};
+
+const char* sd_hires_upscaler_name(enum sd_hires_upscaler_t upscaler) {
+    if (upscaler >= SD_HIRES_UPSCALER_NONE && upscaler < SD_HIRES_UPSCALER_COUNT) {
+        return hires_upscaler_to_str[upscaler];
+    }
+    return NONE_STR;
+}
+
+enum sd_hires_upscaler_t str_to_sd_hires_upscaler(const char* str) {
+    for (int i = 0; i < SD_HIRES_UPSCALER_COUNT; i++) {
+        if (!strcmp(str, hires_upscaler_to_str[i])) {
+            return (enum sd_hires_upscaler_t)i;
+        }
+    }
+    return SD_HIRES_UPSCALER_COUNT;
+}
+
 void sd_cache_params_init(sd_cache_params_t* cache_params) {
     *cache_params                             = {};
     cache_params->mode                        = SD_CACHE_DISABLED;
@@ -2139,6 +2171,19 @@ void sd_cache_params_init(sd_cache_params_t* cache_params) {
     cache_params->spectrum_stop_percent       = 0.9f;
 }
 
+void sd_hires_params_init(sd_hires_params_t* hires_params) {
+    *hires_params                    = {};
+    hires_params->enabled            = false;
+    hires_params->upscaler           = SD_HIRES_UPSCALER_LATENT;
+    hires_params->model_path         = nullptr;
+    hires_params->scale              = 2.0f;
+    hires_params->target_width       = 0;
+    hires_params->target_height      = 0;
+    hires_params->steps              = 0;
+    hires_params->denoising_strength = 0.7f;
+    hires_params->upscale_tile_size  = 128;
+}
+
 void sd_ctx_params_init(sd_ctx_params_t* sd_ctx_params) {
     *sd_ctx_params                         = {};
     sd_ctx_params->vae_decode_only         = true;
@@ -2308,6 +2353,7 @@ void sd_img_gen_params_init(sd_img_gen_params_t* sd_img_gen_params) {
     sd_img_gen_params->pm_params         = {nullptr, 0, nullptr, 20.f};
     sd_img_gen_params->vae_tiling_params = {false, 0, 0, 0.5f, 0.0f, 0.0f};
     sd_cache_params_init(&sd_img_gen_params->cache);
+    sd_hires_params_init(&sd_img_gen_params->hires);
 }
 
 char* sd_img_gen_params_to_str(const sd_img_gen_params_t* sd_img_gen_params) {
@@ -2334,7 +2380,8 @@ char* sd_img_gen_params_to_str(const sd_img_gen_params_t* sd_img_gen_params) {
              "increase_ref_index: %s\n"
              "control_strength: %.2f\n"
              "photo maker: {style_strength = %.2f, id_images_count = %d, id_embed_path = %s}\n"
-             "VAE tiling: %s\n",
+             "VAE tiling: %s\n"
+             "hires: {enabled=%s, upscaler=%s, model_path=%s, scale=%.2f, target=%dx%d, steps=%d, denoising_strength=%.2f}\n",
              SAFE_STR(sd_img_gen_params->prompt),
              SAFE_STR(sd_img_gen_params->negative_prompt),
              sd_img_gen_params->clip_skip,
@@ -2351,7 +2398,15 @@ char* sd_img_gen_params_to_str(const sd_img_gen_params_t* sd_img_gen_params) {
              sd_img_gen_params->pm_params.style_strength,
              sd_img_gen_params->pm_params.id_images_count,
              SAFE_STR(sd_img_gen_params->pm_params.id_embed_path),
-             BOOL_STR(sd_img_gen_params->vae_tiling_params.enabled));
+             BOOL_STR(sd_img_gen_params->vae_tiling_params.enabled),
+             BOOL_STR(sd_img_gen_params->hires.enabled),
+             sd_hires_upscaler_name(sd_img_gen_params->hires.upscaler),
+             SAFE_STR(sd_img_gen_params->hires.model_path),
+             sd_img_gen_params->hires.scale,
+             sd_img_gen_params->hires.target_width,
+             sd_img_gen_params->hires.target_height,
+             sd_img_gen_params->hires.steps,
+             sd_img_gen_params->hires.denoising_strength);
     const char* cache_mode_str = "disabled";
     if (sd_img_gen_params->cache.mode == SD_CACHE_EASYCACHE) {
         cache_mode_str = "easycache";
@@ -2388,6 +2443,14 @@ struct sd_ctx_t {
     StableDiffusionGGML* sd = nullptr;
 };
 
+static bool sd_version_supports_video_generation(SDVersion version) {
+    return version == VERSION_SVD || sd_version_is_wan(version);
+}
+
+static bool sd_version_supports_image_generation(SDVersion version) {
+    return !sd_version_supports_video_generation(version);
+}
+
 sd_ctx_t* new_sd_ctx(const sd_ctx_params_t* sd_ctx_params) {
     sd_ctx_t* sd_ctx = (sd_ctx_t*)malloc(sizeof(sd_ctx_t));
     if (sd_ctx == nullptr) {
@@ -2417,6 +2480,20 @@ void free_sd_ctx(sd_ctx_t* sd_ctx) {
     free(sd_ctx);
 }
 
+SD_API bool sd_ctx_supports_image_generation(const sd_ctx_t* sd_ctx) {
+    if (sd_ctx == nullptr || sd_ctx->sd == nullptr) {
+        return false;
+    }
+    return sd_version_supports_image_generation(sd_ctx->sd->version);
+}
+
+SD_API bool sd_ctx_supports_video_generation(const sd_ctx_t* sd_ctx) {
+    if (sd_ctx == nullptr || sd_ctx->sd == nullptr) {
+        return false;
+    }
+    return sd_version_supports_video_generation(sd_ctx->sd->version);
+}
+
 enum sample_method_t sd_get_default_sample_method(const sd_ctx_t* sd_ctx) {
     if (sd_ctx != nullptr && sd_ctx->sd != nullptr) {
         if (sd_version_is_dit(sd_ctx->sd->version)) {
@@ -2433,8 +2510,10 @@ enum scheduler_t sd_get_default_scheduler(const sd_ctx_t* sd_ctx, enum sample_me
             return EXPONENTIAL_SCHEDULER;
         }
     }
-    if (sample_method == LCM_SAMPLE_METHOD) {
+    if (sample_method == LCM_SAMPLE_METHOD || sample_method == TCD_SAMPLE_METHOD) {
         return LCM_SCHEDULER;
+    } else if (sample_method == DDIM_TRAILING_SAMPLE_METHOD) {
+        return SIMPLE_SCHEDULER;
     }
     return DISCRETE_SCHEDULER;
 }
@@ -2508,6 +2587,7 @@ struct GenerationRequest {
     sd_guidance_params_t guidance            = {};
     sd_guidance_params_t high_noise_guidance = {};
     sd_pm_params_t pm_params                 = {};
+    sd_hires_params_t hires                  = {};
     int frames                               = -1;
     float vace_strength                      = 1.f;
 
@@ -2529,6 +2609,7 @@ struct GenerationRequest {
         auto_resize_ref_image       = sd_img_gen_params->auto_resize_ref_image;
         guidance                    = sd_img_gen_params->sample_params.guidance;
         pm_params                   = sd_img_gen_params->pm_params;
+        hires                       = sd_img_gen_params->hires;
         cache_params                = &sd_img_gen_params->cache;
         resolve(sd_ctx);
     }
@@ -2551,26 +2632,76 @@ struct GenerationRequest {
     }
 
     void align_generation_request_size() {
+        align_image_size(&width, &height, "generation request");
+    }
+
+    void align_image_size(int* target_width, int* target_height, const char* label) {
         int spatial_multiple = vae_scale_factor * diffusion_model_down_factor;
-        int width_offset     = align_up_offset(width, spatial_multiple);
-        int height_offset    = align_up_offset(height, spatial_multiple);
+        int width_offset     = align_up_offset(*target_width, spatial_multiple);
+        int height_offset    = align_up_offset(*target_height, spatial_multiple);
         if (width_offset <= 0 && height_offset <= 0) {
             return;
         }
 
-        int original_width  = width;
-        int original_height = height;
+        int original_width  = *target_width;
+        int original_height = *target_height;
 
-        width += width_offset;
-        height += height_offset;
-        LOG_WARN("align up %dx%d to %dx%d (multiple=%d)",
+        *target_width += width_offset;
+        *target_height += height_offset;
+        LOG_WARN("align %s up %dx%d to %dx%d (multiple=%d)",
+                 label,
                  original_width,
                  original_height,
-                 width,
-                 height,
+                 *target_width,
+                 *target_height,
                  spatial_multiple);
     }
 
+    void resolve_hires() {
+        if (!hires.enabled) {
+            return;
+        }
+        if (hires.upscaler == SD_HIRES_UPSCALER_NONE) {
+            hires.enabled = false;
+            return;
+        }
+        if (hires.upscaler < SD_HIRES_UPSCALER_NONE || hires.upscaler >= SD_HIRES_UPSCALER_COUNT) {
+            LOG_WARN("hires upscaler '%d' is invalid, disabling hires", hires.upscaler);
+            hires.enabled = false;
+            return;
+        }
+        if (hires.upscaler == SD_HIRES_UPSCALER_MODEL && strlen(SAFE_STR(hires.model_path)) == 0) {
+            LOG_WARN("hires model upscaler requires a model path, disabling hires");
+            hires.enabled = false;
+            return;
+        }
+        if (hires.scale <= 0.f && hires.target_width <= 0 && hires.target_height <= 0) {
+            LOG_WARN("hires scale must be positive when no target size is set, disabling hires");
+            hires.enabled = false;
+            return;
+        }
+        hires.denoising_strength = std::clamp(hires.denoising_strength, 0.0001f, 1.f);
+        hires.steps              = std::max(0, hires.steps);
+
+        if (hires.target_width > 0 && hires.target_height > 0) {
+            // pass
+        } else if (hires.target_width > 0) {
+            hires.target_height = hires.target_width;
+        } else if (hires.target_height > 0) {
+            hires.target_width = hires.target_height;
+        } else {
+            hires.target_width  = static_cast<int>(std::round(width * hires.scale));
+            hires.target_height = static_cast<int>(std::round(height * hires.scale));
+        }
+
+        if (hires.target_width <= 0 || hires.target_height <= 0) {
+            LOG_WARN("hires target size is not positive, disabling hires");
+            hires.enabled = false;
+            return;
+        }
+        align_image_size(&hires.target_width, &hires.target_height, "hires target");
+    }
+
     static void resolve_guidance(sd_ctx_t* sd_ctx,
                                  sd_guidance_params_t* guidance,
                                  bool* use_uncond,
@@ -2611,6 +2742,7 @@ struct GenerationRequest {
 
     void resolve(sd_ctx_t* sd_ctx) {
         align_generation_request_size();
+        resolve_hires();
         seed = resolve_seed(seed);
 
         resolve_guidance(sd_ctx, &guidance, &use_uncond, &use_img_cond);
@@ -3123,6 +3255,135 @@ static sd_image_t* decode_image_outputs(sd_ctx_t* sd_ctx,
     return result_images;
 }
 
+static sd::Tensor<float> upscale_hires_latent(sd_ctx_t* sd_ctx,
+                                              const sd::Tensor<float>& latent,
+                                              const GenerationRequest& request,
+                                              UpscalerGGML* upscaler) {
+    auto get_hires_latent_target_shape = [&]() {
+        std::vector<int64_t> target_shape = latent.shape();
+        if (target_shape.size() < 2) {
+            target_shape.clear();
+            return target_shape;
+        }
+        target_shape[0] = request.hires.target_width / request.vae_scale_factor;
+        target_shape[1] = request.hires.target_height / request.vae_scale_factor;
+        return target_shape;
+    };
+
+    if (request.hires.upscaler == SD_HIRES_UPSCALER_LATENT ||
+        request.hires.upscaler == SD_HIRES_UPSCALER_LATENT_NEAREST ||
+        request.hires.upscaler == SD_HIRES_UPSCALER_LATENT_NEAREST_EXACT ||
+        request.hires.upscaler == SD_HIRES_UPSCALER_LATENT_ANTIALIASED ||
+        request.hires.upscaler == SD_HIRES_UPSCALER_LATENT_BICUBIC ||
+        request.hires.upscaler == SD_HIRES_UPSCALER_LATENT_BICUBIC_ANTIALIASED) {
+        std::vector<int64_t> target_shape = get_hires_latent_target_shape();
+        if (target_shape.empty()) {
+            LOG_ERROR("latent has invalid shape for hires upscale");
+            return {};
+        }
+
+        sd::ops::InterpolateMode mode = sd::ops::InterpolateMode::Nearest;
+        bool antialias                = false;
+        switch (request.hires.upscaler) {
+            case SD_HIRES_UPSCALER_LATENT:
+                mode = sd::ops::InterpolateMode::Bilinear;
+                break;
+            case SD_HIRES_UPSCALER_LATENT_NEAREST:
+                mode = sd::ops::InterpolateMode::Nearest;
+                break;
+            case SD_HIRES_UPSCALER_LATENT_NEAREST_EXACT:
+                mode = sd::ops::InterpolateMode::NearestExact;
+                break;
+            case SD_HIRES_UPSCALER_LATENT_ANTIALIASED:
+                mode      = sd::ops::InterpolateMode::Bilinear;
+                antialias = true;
+                break;
+            case SD_HIRES_UPSCALER_LATENT_BICUBIC:
+                mode = sd::ops::InterpolateMode::Bicubic;
+                break;
+            case SD_HIRES_UPSCALER_LATENT_BICUBIC_ANTIALIASED:
+                mode      = sd::ops::InterpolateMode::Bicubic;
+                antialias = true;
+                break;
+            default:
+                break;
+        }
+
+        LOG_INFO("hires %s upscale %" PRId64 "x%" PRId64 " -> %" PRId64 "x%" PRId64,
+                 sd_hires_upscaler_name(request.hires.upscaler),
+                 latent.shape()[0],
+                 latent.shape()[1],
+                 target_shape[0],
+                 target_shape[1]);
+
+        return sd::ops::interpolate(latent, target_shape, mode, false, antialias);
+    } else if (request.hires.upscaler == SD_HIRES_UPSCALER_MODEL ||
+               request.hires.upscaler == SD_HIRES_UPSCALER_LANCZOS ||
+               request.hires.upscaler == SD_HIRES_UPSCALER_NEAREST) {
+        if (sd_ctx->sd->vae_decode_only) {
+            LOG_ERROR("hires %s upscaler requires VAE encoder weights; create the context with vae_decode_only=false",
+                      sd_hires_upscaler_name(request.hires.upscaler));
+            return {};
+        }
+        if (request.hires.upscaler == SD_HIRES_UPSCALER_MODEL && upscaler == nullptr) {
+            LOG_ERROR("hires model upscaler context is null");
+            return {};
+        }
+
+        sd::Tensor<float> decoded = sd_ctx->sd->decode_first_stage(latent);
+        if (decoded.empty()) {
+            LOG_ERROR("decode_first_stage failed before hires %s upscale",
+                      sd_hires_upscaler_name(request.hires.upscaler));
+            return {};
+        }
+
+        sd::Tensor<float> upscaled_tensor;
+        if (request.hires.upscaler == SD_HIRES_UPSCALER_MODEL) {
+            upscaled_tensor = upscaler->upscale_tensor(decoded);
+            if (upscaled_tensor.empty()) {
+                LOG_ERROR("hires model upscale failed");
+                return {};
+            }
+
+            if (upscaled_tensor.shape()[0] != request.hires.target_width ||
+                upscaled_tensor.shape()[1] != request.hires.target_height) {
+                upscaled_tensor = sd::ops::interpolate(upscaled_tensor,
+                                                       {request.hires.target_width,
+                                                        request.hires.target_height,
+                                                        upscaled_tensor.shape()[2],
+                                                        upscaled_tensor.shape()[3]});
+            }
+        } else {
+            sd::ops::InterpolateMode mode = request.hires.upscaler == SD_HIRES_UPSCALER_LANCZOS
+                                                ? sd::ops::InterpolateMode::Lanczos
+                                                : sd::ops::InterpolateMode::Nearest;
+            LOG_INFO("hires %s image upscale %" PRId64 "x%" PRId64 " -> %dx%d",
+                     sd_hires_upscaler_name(request.hires.upscaler),
+                     decoded.shape()[0],
+                     decoded.shape()[1],
+                     request.hires.target_width,
+                     request.hires.target_height);
+            upscaled_tensor = sd::ops::interpolate(decoded,
+                                                   {request.hires.target_width,
+                                                    request.hires.target_height,
+                                                    decoded.shape()[2],
+                                                    decoded.shape()[3]},
+                                                   mode);
+            upscaled_tensor = sd::ops::clamp(upscaled_tensor, 0.0f, 1.0f);
+        }
+
+        sd::Tensor<float> upscaled_latent = sd_ctx->sd->encode_first_stage(upscaled_tensor);
+        if (upscaled_latent.empty()) {
+            LOG_ERROR("encode_first_stage failed after hires %s upscale",
+                      sd_hires_upscaler_name(request.hires.upscaler));
+        }
+        return upscaled_latent;
+    }
+
+    LOG_ERROR("unsupported hires upscaler '%s'", sd_hires_upscaler_name(request.hires.upscaler));
+    return {};
+}
+
 SD_API sd_image_t* generate_image(sd_ctx_t* sd_ctx, const sd_img_gen_params_t* sd_img_gen_params) {
     if (sd_ctx == nullptr || sd_img_gen_params == nullptr) {
         return nullptr;
@@ -3210,7 +3471,7 @@ SD_API sd_image_t* generate_image(sd_ctx_t* sd_ctx, const sd_img_gen_params_t* s
         }
         return nullptr;
     }
-    if (sd_ctx->sd->free_params_immediately) {
+    if (sd_ctx->sd->free_params_immediately && !request.hires.enabled) {
         sd_ctx->sd->diffusion_model->free_params_buffer();
     }
     int64_t denoise_end = ggml_time_ms();
@@ -3218,6 +3479,131 @@ SD_API sd_image_t* generate_image(sd_ctx_t* sd_ctx, const sd_img_gen_params_t* s
              final_latents.size(),
              (denoise_end - denoise_start) * 1.0f / 1000);
 
+    if (request.hires.enabled && request.hires.target_width > 0) {
+        LOG_INFO("hires fix: upscaling to %dx%d", request.hires.target_width, request.hires.target_height);
+
+        std::unique_ptr<UpscalerGGML> hires_upscaler;
+        if (request.hires.upscaler == SD_HIRES_UPSCALER_MODEL) {
+            LOG_INFO("hires fix: loading model upscaler from '%s'", request.hires.model_path);
+            hires_upscaler = std::make_unique<UpscalerGGML>(sd_ctx->sd->n_threads,
+                                                            false,
+                                                            request.hires.upscale_tile_size);
+            if (!hires_upscaler->load_from_file(request.hires.model_path,
+                                                sd_ctx->sd->offload_params_to_cpu,
+                                                sd_ctx->sd->n_threads)) {
+                LOG_ERROR("load hires model upscaler failed");
+                if (sd_ctx->sd->free_params_immediately) {
+                    sd_ctx->sd->diffusion_model->free_params_buffer();
+                }
+                return nullptr;
+            }
+        }
+
+        int hires_steps = request.hires.steps > 0 ? request.hires.steps : plan.sample_steps;
+
+        // sd-webui behavior: scale up total steps so trimming by denoising_strength yields exactly hires_steps effective steps,
+        // unlike img2img which trims from a fixed step count
+        hires_steps = static_cast<int>(hires_steps / request.hires.denoising_strength);
+
+        std::vector<float> hires_sigmas = sd_ctx->sd->denoiser->get_sigmas(
+            hires_steps,
+            sd_ctx->sd->get_image_seq_len(request.hires.target_height, request.hires.target_width),
+            sd_img_gen_params->sample_params.scheduler,
+            sd_ctx->sd->version);
+
+        size_t t_enc = static_cast<size_t>(hires_steps * request.hires.denoising_strength);
+        if (t_enc >= static_cast<size_t>(hires_steps)) {
+            t_enc = static_cast<size_t>(hires_steps) - 1;
+        }
+        std::vector<float> hires_sigma_sched(hires_sigmas.begin() + hires_steps - static_cast<int>(t_enc) - 1,
+                                             hires_sigmas.end());
+        LOG_INFO("hires fix: %d steps, denoising_strength=%.2f, sigma_sched_size=%zu",
+                 hires_steps,
+                 request.hires.denoising_strength,
+                 hires_sigma_sched.size());
+
+        std::vector<sd::Tensor<float>> hires_final_latents;
+        int64_t hires_denoise_start = ggml_time_ms();
+        for (int b = 0; b < (int)final_latents.size(); b++) {
+            int64_t cur_seed = request.seed + b;
+            sd_ctx->sd->rng->manual_seed(cur_seed);
+            sd_ctx->sd->sampler_rng->manual_seed(cur_seed);
+
+            sd::Tensor<float> upscaled = upscale_hires_latent(sd_ctx,
+                                                              final_latents[b],
+                                                              request,
+                                                              hires_upscaler.get());
+            if (upscaled.empty()) {
+                if (sd_ctx->sd->free_params_immediately) {
+                    sd_ctx->sd->diffusion_model->free_params_buffer();
+                }
+                return nullptr;
+            }
+
+            sd::Tensor<float> noise = sd::randn_like<float>(upscaled, sd_ctx->sd->rng);
+
+            sd::Tensor<float> hires_denoise_mask;
+            if (!latents.denoise_mask.empty()) {
+                std::vector<int64_t> mask_shape = latents.denoise_mask.shape();
+                mask_shape[0]                   = upscaled.shape()[0];
+                mask_shape[1]                   = upscaled.shape()[1];
+                hires_denoise_mask              = sd::ops::interpolate(latents.denoise_mask,
+                                                                       mask_shape,
+                                                                       sd::ops::InterpolateMode::NearestMax);
+            }
+
+            int64_t hires_sample_start = ggml_time_ms();
+            sd::Tensor<float> x_0      = sd_ctx->sd->sample(sd_ctx->sd->diffusion_model,
+                                                            true,
+                                                            upscaled,
+                                                            std::move(noise),
+                                                            embeds.cond,
+                                                            embeds.uncond,
+                                                            embeds.img_cond,
+                                                            embeds.id_cond,
+                                                            latents.control_image,
+                                                            request.control_strength,
+                                                            request.guidance,
+                                                            plan.eta,
+                                                            request.shifted_timestep,
+                                                            plan.sample_method,
+                                                            sd_ctx->sd->is_flow_denoiser(),
+                                                            hires_sigma_sched,
+                                                            plan.start_merge_step,
+                                                            latents.ref_latents,
+                                                            request.increase_ref_index,
+                                                            hires_denoise_mask,
+                                                            sd::Tensor<float>(),
+                                                            1.f,
+                                                            request.cache_params);
+            int64_t hires_sample_end   = ggml_time_ms();
+            if (!x_0.empty()) {
+                LOG_INFO("hires sampling %d/%d completed, taking %.2fs",
+                         b + 1,
+                         (int)final_latents.size(),
+                         (hires_sample_end - hires_sample_start) * 1.0f / 1000);
+                hires_final_latents.push_back(std::move(x_0));
+                continue;
+            }
+
+            LOG_ERROR("hires sampling for image %d/%d failed after %.2fs",
+                      b + 1,
+                      (int)final_latents.size(),
+                      (hires_sample_end - hires_sample_start) * 1.0f / 1000);
+            if (sd_ctx->sd->free_params_immediately) {
+                sd_ctx->sd->diffusion_model->free_params_buffer();
+            }
+            return nullptr;
+        }
+        if (sd_ctx->sd->free_params_immediately) {
+            sd_ctx->sd->diffusion_model->free_params_buffer();
+        }
+        int64_t hires_denoise_end = ggml_time_ms();
+        LOG_INFO("hires fix completed, taking %.2fs", (hires_denoise_end - hires_denoise_start) * 1.0f / 1000);
+
+        final_latents = std::move(hires_final_latents);
+    }
+
     auto result = decode_image_outputs(sd_ctx, request, final_latents);
     if (result == nullptr) {
         return nullptr;

src/tensor.hpp

@@ -815,11 +815,202 @@ namespace sd {
     namespace ops {
         enum class InterpolateMode {
             Nearest,
+            NearestExact,
             NearestMax,
             NearestMin,
             NearestAvg,
+            Bilinear,
+            Bicubic,
+            Lanczos,
         };
 
+        inline bool is_nearest_like_interpolate_mode(InterpolateMode mode) {
+            return mode == InterpolateMode::Nearest ||
+                   mode == InterpolateMode::NearestExact ||
+                   mode == InterpolateMode::NearestMax ||
+                   mode == InterpolateMode::NearestMin ||
+                   mode == InterpolateMode::NearestAvg;
+        }
+
+        inline bool is_2d_filter_interpolate_mode(InterpolateMode mode) {
+            return mode == InterpolateMode::Bilinear ||
+                   mode == InterpolateMode::Bicubic ||
+                   mode == InterpolateMode::Lanczos;
+        }
+
+        inline int64_t nearest_exact_interpolate_index(int64_t output_index,
+                                                       int64_t input_size,
+                                                       int64_t output_size) {
+            const double scale  = static_cast<double>(input_size) / static_cast<double>(output_size);
+            const double center = (static_cast<double>(output_index) + 0.5) * scale - 0.5;
+            return std::min(std::max<int64_t>(static_cast<int64_t>(std::floor(center + 0.5)), 0), input_size - 1);
+        }
+
+        inline double linear_interpolate_weight(double x) {
+            x = std::abs(x);
+            return x < 1.0 ? 1.0 - x : 0.0;
+        }
+
+        inline double cubic_interpolate_weight(double x) {
+            constexpr double a = -0.75;  // Match PyTorch bicubic interpolation.
+            x                  = std::abs(x);
+            if (x <= 1.0) {
+                return ((a + 2.0) * x - (a + 3.0)) * x * x + 1.0;
+            }
+            if (x < 2.0) {
+                return ((a * x - 5.0 * a) * x + 8.0 * a) * x - 4.0 * a;
+            }
+            return 0.0;
+        }
+
+        inline double sinc(double x) {
+            constexpr double pi = 3.14159265358979323846;
+            if (std::abs(x) < 1e-12) {
+                return 1.0;
+            }
+            const double pix = pi * x;
+            return std::sin(pix) / pix;
+        }
+
+        inline double lanczos_interpolate_weight(double x) {
+            constexpr double radius = 3.0;
+            x                       = std::abs(x);
+            if (x >= radius) {
+                return 0.0;
+            }
+            return sinc(x) * sinc(x / radius);
+        }
+
+        struct InterpolateContributor {
+            int64_t index;
+            double weight;
+        };
+
+        inline std::vector<std::vector<InterpolateContributor>> make_interpolate_contributors(
+            int64_t input_size,
+            int64_t output_size,
+            InterpolateMode mode,
+            bool antialias) {
+            std::vector<std::vector<InterpolateContributor>> contributors(static_cast<size_t>(output_size));
+            const double scale        = static_cast<double>(input_size) / static_cast<double>(output_size);
+            const double filter_scale = antialias ? std::max(1.0, scale) : 1.0;
+
+            for (int64_t out = 0; out < output_size; ++out) {
+                const double center = (static_cast<double>(out) + 0.5) * scale - 0.5;
+                int64_t start       = 0;
+                int64_t end         = 0;
+
+                if (mode == InterpolateMode::Bilinear) {
+                    const double support = filter_scale;
+                    start                = static_cast<int64_t>(std::ceil(center - support));
+                    end                  = static_cast<int64_t>(std::floor(center + support));
+                } else if (mode == InterpolateMode::Bicubic) {
+                    const double support = 2.0 * filter_scale;
+                    start                = static_cast<int64_t>(std::ceil(center - support));
+                    end                  = static_cast<int64_t>(std::floor(center + support));
+                } else if (mode == InterpolateMode::Lanczos) {
+                    const double support = 3.0 * filter_scale;
+                    start                = static_cast<int64_t>(std::ceil(center - support));
+                    end                  = static_cast<int64_t>(std::floor(center + support));
+                } else {
+                    tensor_throw_invalid_argument("Unsupported 2D filter interpolate mode: mode=" +
+                                                  std::to_string(static_cast<int>(mode)));
+                }
+
+                double weight_sum                                      = 0.0;
+                std::vector<InterpolateContributor>& axis_contributors = contributors[static_cast<size_t>(out)];
+                axis_contributors.reserve(static_cast<size_t>(end - start + 1));
+
+                for (int64_t in = start; in <= end; ++in) {
+                    double weight = 0.0;
+                    if (mode == InterpolateMode::Bilinear) {
+                        weight = linear_interpolate_weight((center - static_cast<double>(in)) / filter_scale);
+                    } else if (mode == InterpolateMode::Bicubic) {
+                        weight = cubic_interpolate_weight((center - static_cast<double>(in)) / filter_scale);
+                    } else {
+                        weight = lanczos_interpolate_weight((center - static_cast<double>(in)) / filter_scale);
+                    }
+
+                    if (weight == 0.0) {
+                        continue;
+                    }
+
+                    const int64_t clamped_index = std::min(std::max<int64_t>(in, 0), input_size - 1);
+                    axis_contributors.push_back({clamped_index, weight});
+                    weight_sum += weight;
+                }
+
+                if ((antialias || mode == InterpolateMode::Lanczos) &&
+                    std::abs(weight_sum) > 1e-12) {
+                    for (auto& contributor : axis_contributors) {
+                        contributor.weight /= weight_sum;
+                    }
+                }
+
+                if (axis_contributors.empty()) {
+                    const int64_t nearest = std::min(
+                        std::max<int64_t>(static_cast<int64_t>(std::floor(center + 0.5)), 0),
+                        input_size - 1);
+                    axis_contributors.push_back({nearest, 1.0});
+                }
+            }
+
+            return contributors;
+        }
+
+        template <typename T>
+        inline Tensor<T> interpolate_2d_filter(const Tensor<T>& input,
+                                               const std::vector<int64_t>& output_shape,
+                                               InterpolateMode mode,
+                                               bool antialias) {
+            if (input.dim() < 2) {
+                tensor_throw_invalid_argument("2D filter interpolate requires rank >= 2: input_shape=" +
+                                              tensor_shape_to_string(input.shape()) + ", output_shape=" +
+                                              tensor_shape_to_string(output_shape));
+            }
+            for (size_t i = 2; i < output_shape.size(); ++i) {
+                if (input.shape()[i] != output_shape[i]) {
+                    tensor_throw_invalid_argument("2D filter interpolate only supports resizing dimensions 0 and 1: input_shape=" +
+                                                  tensor_shape_to_string(input.shape()) + ", output_shape=" +
+                                                  tensor_shape_to_string(output_shape));
+                }
+            }
+
+            Tensor<T> output(output_shape);
+            const int64_t input_width   = input.shape()[0];
+            const int64_t input_height  = input.shape()[1];
+            const int64_t output_width  = output_shape[0];
+            const int64_t output_height = output_shape[1];
+            const int64_t input_plane   = input_width * input_height;
+            const int64_t output_plane  = output_width * output_height;
+            const int64_t plane_count   = input.numel() / input_plane;
+
+            auto x_contributors = make_interpolate_contributors(input_width, output_width, mode, antialias);
+            auto y_contributors = make_interpolate_contributors(input_height, output_height, mode, antialias);
+
+            for (int64_t plane = 0; plane < plane_count; ++plane) {
+                const int64_t input_plane_offset  = plane * input_plane;
+                const int64_t output_plane_offset = plane * output_plane;
+                for (int64_t y = 0; y < output_height; ++y) {
+                    const auto& y_axis = y_contributors[static_cast<size_t>(y)];
+                    for (int64_t x = 0; x < output_width; ++x) {
+                        const auto& x_axis = x_contributors[static_cast<size_t>(x)];
+                        double value       = 0.0;
+                        for (const auto& yc : y_axis) {
+                            const int64_t input_row_offset = input_plane_offset + yc.index * input_width;
+                            for (const auto& xc : x_axis) {
+                                value += static_cast<double>(input.data()[input_row_offset + xc.index]) *
+                                         xc.weight * yc.weight;
+                            }
+                        }
+                        output.data()[output_plane_offset + y * output_width + x] = static_cast<T>(value);
+                    }
+                }
+            }
+
+            return output;
+        }
+
         inline int64_t normalize_slice_bound(int64_t index, int64_t dim_size) {
             if (index < 0) {
                 index += dim_size;
@@ -1014,17 +1205,20 @@ namespace sd {
         inline Tensor<T> interpolate(const Tensor<T>& input,
                                      std::vector<int64_t> output_shape,
                                      InterpolateMode mode = InterpolateMode::Nearest,
-                                     bool align_corners   = false) {
-            const bool is_nearest_like_mode = (mode == InterpolateMode::Nearest ||
-                                               mode == InterpolateMode::NearestMax ||
-                                               mode == InterpolateMode::NearestMin ||
-                                               mode == InterpolateMode::NearestAvg);
-            if (!is_nearest_like_mode) {
-                tensor_throw_invalid_argument("Only nearest-like interpolate modes are implemented, got mode=" +
+                                     bool align_corners   = false,
+                                     bool antialias       = false) {
+            const bool is_nearest_like_mode = is_nearest_like_interpolate_mode(mode);
+            const bool is_2d_filter_mode    = is_2d_filter_interpolate_mode(mode);
+            if (!is_nearest_like_mode && !is_2d_filter_mode) {
+                tensor_throw_invalid_argument("Unsupported interpolate mode: mode=" +
+                                              std::to_string(static_cast<int>(mode)));
+            }
+            if (antialias && !is_2d_filter_mode) {
+                tensor_throw_invalid_argument("Tensor interpolate antialias requires a 2D filter mode: mode=" +
                                               std::to_string(static_cast<int>(mode)));
             }
             if (align_corners) {
-                tensor_throw_invalid_argument("align_corners is not supported for nearest-like interpolate: input_shape=" +
+                tensor_throw_invalid_argument("align_corners is not supported for tensor interpolate: input_shape=" +
                                               tensor_shape_to_string(input.shape()) + ", output_shape=" +
                                               tensor_shape_to_string(output_shape));
             }
@@ -1051,6 +1245,10 @@ namespace sd {
                 }
             }
 
+            if (is_2d_filter_mode) {
+                return interpolate_2d_filter(input, output_shape, mode, antialias);
+            }
+
             bool has_downsampling = false;
             for (int64_t i = 0; i < input.dim(); ++i) {
                 if (input.shape()[i] > output_shape[i]) {
@@ -1060,12 +1258,20 @@ namespace sd {
             }
 
             Tensor<T> output(std::move(output_shape));
-            if (mode == InterpolateMode::Nearest || !has_downsampling) {
+            if (mode == InterpolateMode::Nearest ||
+                mode == InterpolateMode::NearestExact ||
+                !has_downsampling) {
                 for (int64_t flat = 0; flat < output.numel(); ++flat) {
                     std::vector<int64_t> output_coord = tensor_unravel_index(flat, output.shape());
                     std::vector<int64_t> input_coord(static_cast<size_t>(input.dim()), 0);
                     for (size_t i = 0; i < static_cast<size_t>(input.dim()); ++i) {
-                        input_coord[i] = output_coord[i] * input.shape()[i] / output.shape()[i];
+                        if (mode == InterpolateMode::NearestExact) {
+                            input_coord[i] = nearest_exact_interpolate_index(output_coord[i],
+                                                                             input.shape()[i],
+                                                                             output.shape()[i]);
+                        } else {
+                            input_coord[i] = output_coord[i] * input.shape()[i] / output.shape()[i];
+                        }
                     }
                     output[flat] = input.index(input_coord);
                 }
@@ -1083,6 +1289,12 @@ namespace sd {
                         return T(0);
                     case InterpolateMode::Nearest:
                         return T(0);
+                    case InterpolateMode::NearestExact:
+                        return T(0);
+                    case InterpolateMode::Bilinear:
+                    case InterpolateMode::Bicubic:
+                    case InterpolateMode::Lanczos:
+                        break;
                 }
 
                 tensor_throw_invalid_argument("Unsupported interpolate mode: mode=" +
@@ -1102,6 +1314,12 @@ namespace sd {
                         break;
                     case InterpolateMode::Nearest:
                         break;
+                    case InterpolateMode::NearestExact:
+                        break;
+                    case InterpolateMode::Bilinear:
+                    case InterpolateMode::Bicubic:
+                    case InterpolateMode::Lanczos:
+                        break;
                 }
             };
 
@@ -1157,17 +1375,20 @@ namespace sd {
                                      const std::optional<std::vector<int64_t>>& size,
                                      const std::optional<std::vector<double>>& scale_factor,
                                      InterpolateMode mode = InterpolateMode::Nearest,
-                                     bool align_corners   = false) {
-            const bool is_nearest_like_mode = (mode == InterpolateMode::Nearest ||
-                                               mode == InterpolateMode::NearestMax ||
-                                               mode == InterpolateMode::NearestMin ||
-                                               mode == InterpolateMode::NearestAvg);
-            if (!is_nearest_like_mode) {
-                tensor_throw_invalid_argument("Only nearest-like interpolate modes are implemented, got mode=" +
+                                     bool align_corners   = false,
+                                     bool antialias       = false) {
+            const bool is_nearest_like_mode = is_nearest_like_interpolate_mode(mode);
+            const bool is_2d_filter_mode    = is_2d_filter_interpolate_mode(mode);
+            if (!is_nearest_like_mode && !is_2d_filter_mode) {
+                tensor_throw_invalid_argument("Unsupported interpolate mode: mode=" +
+                                              std::to_string(static_cast<int>(mode)));
+            }
+            if (antialias && !is_2d_filter_mode) {
+                tensor_throw_invalid_argument("Tensor interpolate antialias requires a 2D filter mode: mode=" +
                                               std::to_string(static_cast<int>(mode)));
             }
             if (align_corners) {
-                tensor_throw_invalid_argument("align_corners is not supported for nearest-like interpolate: input_shape=" +
+                tensor_throw_invalid_argument("align_corners is not supported for tensor interpolate: input_shape=" +
                                               tensor_shape_to_string(input.shape()));
             }
             if (size.has_value() == scale_factor.has_value()) {
@@ -1211,7 +1432,7 @@ namespace sd {
                 }
             }
 
-            return interpolate(input, std::move(output_shape), mode, align_corners);
+            return interpolate(input, std::move(output_shape), mode, align_corners, antialias);
         }
 
         template <typename T>
@@ -1219,12 +1440,14 @@ namespace sd {
                                      const std::optional<std::vector<int64_t>>& size,
                                      double scale_factor,
                                      InterpolateMode mode = InterpolateMode::Nearest,
-                                     bool align_corners   = false) {
+                                     bool align_corners   = false,
+                                     bool antialias       = false) {
             return interpolate(input,
                                size,
                                std::vector<double>(size.has_value() ? size->size() : input.dim(), scale_factor),
                                mode,
-                               align_corners);
+                               align_corners,
+                               antialias);
         }
 
         template <typename T>

src/upscaler.cpp

@@ -1,125 +1,115 @@
-#include "esrgan.hpp"
+#include "upscaler.h"
 #include "ggml_extend.hpp"
 #include "model.h"
 #include "stable-diffusion.h"
 #include "util.h"
 
-struct UpscalerGGML {
-    ggml_backend_t backend    = nullptr;  // general backend
-    ggml_type model_data_type = GGML_TYPE_F16;
-    std::shared_ptr<ESRGAN> esrgan_upscaler;
-    std::string esrgan_path;
-    int n_threads;
-    bool direct   = false;
-    int tile_size = 128;
+UpscalerGGML::UpscalerGGML(int n_threads,
+                           bool direct,
+                           int tile_size)
+    : n_threads(n_threads),
+      direct(direct),
+      tile_size(tile_size) {
+}
 
-    UpscalerGGML(int n_threads,
-                 bool direct   = false,
-                 int tile_size = 128)
-        : n_threads(n_threads),
-          direct(direct),
-          tile_size(tile_size) {
-    }
-
-    bool load_from_file(const std::string& esrgan_path,
-                        bool offload_params_to_cpu,
-                        int n_threads) {
-        ggml_log_set(ggml_log_callback_default, nullptr);
+bool UpscalerGGML::load_from_file(const std::string& esrgan_path,
+                                  bool offload_params_to_cpu,
+                                  int n_threads) {
+    ggml_log_set(ggml_log_callback_default, nullptr);
 #ifdef SD_USE_CUDA
-        LOG_DEBUG("Using CUDA backend");
-        backend = ggml_backend_cuda_init(0);
+    LOG_DEBUG("Using CUDA backend");
+    backend = ggml_backend_cuda_init(0);
 #endif
 #ifdef SD_USE_METAL
-        LOG_DEBUG("Using Metal backend");
-        backend = ggml_backend_metal_init();
+    LOG_DEBUG("Using Metal backend");
+    backend = ggml_backend_metal_init();
 #endif
 #ifdef SD_USE_VULKAN
-        LOG_DEBUG("Using Vulkan backend");
-        backend = ggml_backend_vk_init(0);
+    LOG_DEBUG("Using Vulkan backend");
+    backend = ggml_backend_vk_init(0);
 #endif
 #ifdef SD_USE_OPENCL
-        LOG_DEBUG("Using OpenCL backend");
-        backend = ggml_backend_opencl_init();
+    LOG_DEBUG("Using OpenCL backend");
+    backend = ggml_backend_opencl_init();
 #endif
 #ifdef SD_USE_SYCL
-        LOG_DEBUG("Using SYCL backend");
-        backend = ggml_backend_sycl_init(0);
+    LOG_DEBUG("Using SYCL backend");
+    backend = ggml_backend_sycl_init(0);
 #endif
-        ModelLoader model_loader;
-        if (!model_loader.init_from_file_and_convert_name(esrgan_path)) {
-            LOG_ERROR("init model loader from file failed: '%s'", esrgan_path.c_str());
-        }
-        model_loader.set_wtype_override(model_data_type);
-        if (!backend) {
-            LOG_DEBUG("Using CPU backend");
-            backend = ggml_backend_cpu_init();
-        }
-        LOG_INFO("Upscaler weight type: %s", ggml_type_name(model_data_type));
-        esrgan_upscaler = std::make_shared<ESRGAN>(backend, offload_params_to_cpu, tile_size, model_loader.get_tensor_storage_map());
-        if (direct) {
-            esrgan_upscaler->set_conv2d_direct_enabled(true);
-        }
-        if (!esrgan_upscaler->load_from_file(esrgan_path, n_threads)) {
-            return false;
-        }
-        return true;
+    ModelLoader model_loader;
+    if (!model_loader.init_from_file_and_convert_name(esrgan_path)) {
+        LOG_ERROR("init model loader from file failed: '%s'", esrgan_path.c_str());
     }
-
-    sd::Tensor<float> upscale_tensor(const sd::Tensor<float>& input_tensor) {
-        sd::Tensor<float> upscaled;
-        if (tile_size <= 0 || (input_tensor.shape()[0] <= tile_size && input_tensor.shape()[1] <= tile_size)) {
-            upscaled = esrgan_upscaler->compute(n_threads, input_tensor);
-        } else {
-            auto on_processing = [&](const sd::Tensor<float>& input_tile) -> sd::Tensor<float> {
-                auto output_tile = esrgan_upscaler->compute(n_threads, input_tile);
-                if (output_tile.empty()) {
-                    LOG_ERROR("esrgan compute failed while processing a tile");
-                    return {};
-                }
-                return output_tile;
-            };
-
-            upscaled = process_tiles_2d(input_tensor,
-                                        static_cast<int>(input_tensor.shape()[0] * esrgan_upscaler->scale),
-                                        static_cast<int>(input_tensor.shape()[1] * esrgan_upscaler->scale),
-                                        esrgan_upscaler->scale,
-                                        tile_size,
-                                        tile_size,
-                                        0.25f,
-                                        false,
-                                        false,
-                                        on_processing);
-        }
-        esrgan_upscaler->free_compute_buffer();
-        if (upscaled.empty()) {
-            LOG_ERROR("esrgan compute failed");
-            return {};
-        }
-        return upscaled;
+    model_loader.set_wtype_override(model_data_type);
+    if (!backend) {
+        LOG_DEBUG("Using CPU backend");
+        backend = ggml_backend_cpu_init();
     }
+    LOG_INFO("Upscaler weight type: %s", ggml_type_name(model_data_type));
+    esrgan_upscaler = std::make_shared<ESRGAN>(backend, offload_params_to_cpu, tile_size, model_loader.get_tensor_storage_map());
+    if (direct) {
+        esrgan_upscaler->set_conv2d_direct_enabled(true);
+    }
+    if (!esrgan_upscaler->load_from_file(esrgan_path, n_threads)) {
+        return false;
+    }
+    return true;
+}
 
-    sd_image_t upscale(sd_image_t input_image, uint32_t upscale_factor) {
-        // upscale_factor, unused for RealESRGAN_x4plus_anime_6B.pth
-        sd_image_t upscaled_image = {0, 0, 0, nullptr};
-        int output_width          = (int)input_image.width * esrgan_upscaler->scale;
-        int output_height         = (int)input_image.height * esrgan_upscaler->scale;
-        LOG_INFO("upscaling from (%i x %i) to (%i x %i)",
-                 input_image.width, input_image.height, output_width, output_height);
+sd::Tensor<float> UpscalerGGML::upscale_tensor(const sd::Tensor<float>& input_tensor) {
+    sd::Tensor<float> upscaled;
+    if (tile_size <= 0 || (input_tensor.shape()[0] <= tile_size && input_tensor.shape()[1] <= tile_size)) {
+        upscaled = esrgan_upscaler->compute(n_threads, input_tensor);
+    } else {
+        auto on_processing = [&](const sd::Tensor<float>& input_tile) -> sd::Tensor<float> {
+            auto output_tile = esrgan_upscaler->compute(n_threads, input_tile);
+            if (output_tile.empty()) {
+                LOG_ERROR("esrgan compute failed while processing a tile");
+                return {};
+            }
+            return output_tile;
+        };
 
-        sd::Tensor<float> input_tensor = sd_image_to_tensor(input_image);
-        sd::Tensor<float> upscaled;
-        int64_t t0 = ggml_time_ms();
-        upscaled   = upscale_tensor(input_tensor);
-        if (upscaled.empty()) {
-            return upscaled_image;
-        }
-        sd_image_t upscaled_data = tensor_to_sd_image(upscaled);
-        int64_t t3               = ggml_time_ms();
-        LOG_INFO("input_image_tensor upscaled, taking %.2fs", (t3 - t0) / 1000.0f);
-        upscaled_image = upscaled_data;
+        upscaled = process_tiles_2d(input_tensor,
+                                    static_cast<int>(input_tensor.shape()[0] * esrgan_upscaler->scale),
+                                    static_cast<int>(input_tensor.shape()[1] * esrgan_upscaler->scale),
+                                    esrgan_upscaler->scale,
+                                    tile_size,
+                                    tile_size,
+                                    0.25f,
+                                    false,
+                                    false,
+                                    on_processing);
+    }
+    esrgan_upscaler->free_compute_buffer();
+    if (upscaled.empty()) {
+        LOG_ERROR("esrgan compute failed");
+        return {};
+    }
+    return upscaled;
+}
+
+sd_image_t UpscalerGGML::upscale(sd_image_t input_image, uint32_t upscale_factor) {
+    // upscale_factor, unused for RealESRGAN_x4plus_anime_6B.pth
+    sd_image_t upscaled_image = {0, 0, 0, nullptr};
+    int output_width          = (int)input_image.width * esrgan_upscaler->scale;
+    int output_height         = (int)input_image.height * esrgan_upscaler->scale;
+    LOG_INFO("upscaling from (%i x %i) to (%i x %i)",
+             input_image.width, input_image.height, output_width, output_height);
+
+    sd::Tensor<float> input_tensor = sd_image_to_tensor(input_image);
+    sd::Tensor<float> upscaled;
+    int64_t t0 = ggml_time_ms();
+    upscaled   = upscale_tensor(input_tensor);
+    if (upscaled.empty()) {
         return upscaled_image;
     }
-};
+    sd_image_t upscaled_data = tensor_to_sd_image(upscaled);
+    int64_t t3               = ggml_time_ms();
+    LOG_INFO("input_image_tensor upscaled, taking %.2fs", (t3 - t0) / 1000.0f);
+    upscaled_image = upscaled_data;
+    return upscaled_image;
+}
 
 struct upscaler_ctx_t {
     UpscalerGGML* upscaler = nullptr;

src/upscaler.h

@@ -0,0 +1,31 @@
+#ifndef __SD_UPSCALER_H__
+#define __SD_UPSCALER_H__
+
+#include "esrgan.hpp"
+#include "stable-diffusion.h"
+#include "tensor.hpp"
+
+#include <memory>
+#include <string>
+
+struct UpscalerGGML {
+    ggml_backend_t backend    = nullptr;  // general backend
+    ggml_type model_data_type = GGML_TYPE_F16;
+    std::shared_ptr<ESRGAN> esrgan_upscaler;
+    std::string esrgan_path;
+    int n_threads;
+    bool direct   = false;
+    int tile_size = 128;
+
+    UpscalerGGML(int n_threads,
+                 bool direct   = false,
+                 int tile_size = 128);
+
+    bool load_from_file(const std::string& esrgan_path,
+                        bool offload_params_to_cpu,
+                        int n_threads);
+    sd::Tensor<float> upscale_tensor(const sd::Tensor<float>& input_tensor);
+    sd_image_t upscale(sd_image_t input_image, uint32_t upscale_factor);
+};
+
+#endif  // __SD_UPSCALER_H__