feat: add linear and attention scale overrides (#1964)

examples/cli/README.md

@@ -22,3 +22,6 @@ Metadata mode inspects PNG/JPEG container metadata without loading any model:
 ./bin/sd-cli -M metadata --image ./output.png --metadata-raw
 ./bin/sd-cli -M metadata --image ./output.png --metadata-all
 ```
+
+For completely black or white images or videos, NaNs, and the `--linear-scale` /
+`--attn-scale` workaround, see [Troubleshooting](../../docs/troubleshooting.md).

examples/common/common.cpp

@@ -359,6 +359,25 @@ bool parse_options(int argc, const char** argv, const std::vector<ArgOptions>& o
     return true;
 }
 
+static int parse_scale_override(int argc, const char** argv, int index, float& scale) {
+    if (++index >= argc) {
+        return -1;
+    }
+    try {
+        size_t end              = 0;
+        const std::string value = argv[index];
+        float parsed            = std::stof(value, &end);
+        if (end != value.size() || !std::isfinite(parsed) || parsed < 0.f ||
+            (parsed > 0.f && !std::isfinite(1.f / parsed))) {
+            return -1;
+        }
+        scale = parsed;
+    } catch (const std::exception&) {
+        return -1;
+    }
+    return 1;
+}
+
 ArgOptions SDContextParams::get_options() {
     ArgOptions options;
     options.string_options = {
@@ -687,6 +706,18 @@ ArgOptions SDContextParams::get_options() {
     };
 
     options.manual_options = {
+        {"",
+         "--linear-scale",
+         "linear input scale override (float, default: 0 = model default, 1 = no scaling)",
+         [this](int argc, const char** argv, int index) {
+             return parse_scale_override(argc, argv, index, linear_scale);
+         }},
+        {"",
+         "--attn-scale",
+         "flash-attention K/V scale override (float, default: 0 = model default, 1 = no scaling); requires --fa or --diffusion-fa",
+         [this](int argc, const char** argv, int index) {
+             return parse_scale_override(argc, argv, index, attn_scale);
+         }},
         {"",
          "--auto-fit",
          "on|off (default: on). Use one GPU for diffusion/te/vae computation and place weights on that GPU, "
@@ -895,6 +926,8 @@ std::string SDContextParams::to_string() const {
         << "  vae_on_cpu: " << (vae_on_cpu ? "true" : "false") << ",\n"
         << "  flash_attn: " << (flash_attn ? "true" : "false") << ",\n"
         << "  diffusion_flash_attn: " << (diffusion_flash_attn ? "true" : "false") << ",\n"
+        << "  linear_scale: " << linear_scale << ",\n"
+        << "  attn_scale: " << attn_scale << ",\n"
         << "  diffusion_conv_direct: " << (diffusion_conv_direct ? "true" : "false") << ",\n"
         << "  vae_conv_direct: " << (vae_conv_direct ? "true" : "false") << ",\n"
         << "  prediction: " << sd_prediction_name(prediction) << ",\n"
@@ -948,6 +981,8 @@ sd_ctx_params_t SDContextParams::to_sd_ctx_params_t(bool taesd_preview) {
     sd_ctx_params.enable_mmap                     = enable_mmap;
     sd_ctx_params.flash_attn                      = flash_attn;
     sd_ctx_params.diffusion_flash_attn            = diffusion_flash_attn;
+    sd_ctx_params.linear_scale                    = linear_scale;
+    sd_ctx_params.attn_scale                      = attn_scale;
     sd_ctx_params.tae_preview_only                = taesd_preview;
     sd_ctx_params.diffusion_conv_direct           = diffusion_conv_direct;
     sd_ctx_params.vae_conv_direct                 = vae_conv_direct;

examples/common/common.h

@@ -175,6 +175,8 @@ struct SDContextParams {
     lora_apply_mode_t lora_apply_mode = LORA_APPLY_AUTO;
 
     bool force_sdxl_vae_conv_scale = false;
+    float linear_scale             = 0.f;
+    float attn_scale               = 0.f;
 
     float flow_shift = INFINITY;
     ArgOptions get_options();

examples/server/README.md

@@ -129,3 +129,6 @@ For detailed command-line arguments, run:
 ```bash
 ./bin/sd-server -h
 ```
+
+For completely black or white images or videos, NaNs, and the `--linear-scale` /
+`--attn-scale` startup options, see [Troubleshooting](../../docs/troubleshooting.md).