VoiceStudio/scripts/build_dub_demo.sh

#!/bin/bash
# Build the synthetic dubbing demo: one English source video + 4 dubbed
# variants. Each video is a 720p H.264 file with the showwaves audio
# visualizer over a dark gradient background — no copyrighted footage,
# no third-party voice IP.
#
# Output layout (under backend/assets/demo/dubbing/):
#   source.mp4         English audio + visualizer
#   dubbed_es.mp4      Spanish (Mónica)
#   dubbed_fr.mp4      French (Thomas)
#   dubbed_zh.mp4      Mandarin (Tingting)
#   dubbed_ja.mp4      Japanese (Kyoko)
#   *.srt              transcripts for each
#   manifest.json      single source of truth the frontend reads
#
# Bundle target: ~5 MB per mp4 × 5 files = ~25 MB. Well under the 45 MB
# cap from the dubbing-demo design spec.

set -e
REPO_ROOT="$(cd "$(dirname "$0")/.." && pwd)"
OUT_DIR="${REPO_ROOT}/backend/assets/samples/demo/dubbing"
mkdir -p "$OUT_DIR"

# Compatibility: must run on macOS default bash 3.2 (no associative arrays,
# no ${var@Q}). We sidestep both by passing scripts as env vars to python3
# below. Just guard the basics.
if ! command -v ffmpeg >/dev/null; then
  echo "ERROR: ffmpeg not found." >&2
  exit 1
fi
# `say` is macOS-only, which used to make this script macOS-only and left the
# Dub workspace's demo player pointing at files no other platform could build.
# scripts/render_dub_demo_audio.py renders the same five tracks with the app's
# own engine, anywhere; `say` is now the fallback, not the requirement.
HAVE_SAY=0
command -v say >/dev/null && HAVE_SAY=1
# Check EVERY track, not just the source. Checking one let a run start with
# four of five present, reach a missing dubbed track, call `say` — which does
# not exist off macOS — and leave a half-built bundle behind.
if [ "$HAVE_SAY" = 0 ]; then
  MISSING=""
  for stem in source dubbed_es dubbed_fr dubbed_zh dubbed_ja; do
    [ -f "${OUT_DIR}/${stem}.src.wav" ] || MISSING="${MISSING} ${stem}.src.wav"
  done
  if [ -n "$MISSING" ]; then
    echo "ERROR: no macOS 'say', and these pre-rendered tracks are missing:${MISSING}" >&2
    echo "Run: python3 scripts/render_dub_demo_audio.py" >&2
    exit 1
  fi
fi
if ! command -v python3 >/dev/null; then
  echo "ERROR: python3 not found — needed to emit manifest.json." >&2
  exit 1
fi

# ── Scripts: source + 4 translations ─────────────────────────────────────
# Read from scripts/dub_demo_scripts.json, which render_dub_demo_audio.py reads
# too — two copies of the same five paragraphs is one edit away from a source
# video whose subtitles say something else.
SCRIPTS_JSON="${REPO_ROOT}/scripts/dub_demo_scripts.json"
read_script() {
  SCRIPTS_JSON="$SCRIPTS_JSON" CODE="$1" python3 -c "
import json, os, sys
spec = json.load(open(os.environ['SCRIPTS_JSON'], encoding='utf-8'))
code = os.environ['CODE']
entry = spec['source'] if code == 'en' else next(
    e for e in spec['dubbed'] if e['code'] == code)
sys.stdout.write(entry['script'])
"
}

EN_SCRIPT="$(read_script en)"
ES_SCRIPT="$(read_script es)"
FR_SCRIPT="$(read_script fr)"
ZH_SCRIPT="$(read_script zh)"
JA_SCRIPT="$(read_script ja)"

# ── render_lang(code, voice, text) ──────────────────────────────────────
#   Produces: $OUT_DIR/{source|dubbed_$code}.mp4 + matching .srt
# Uses showwaves to render a styled audio visualizer over a dark backdrop.
# Resolution 1280x720 keeps each output around 4-6 MB at CRF 28.
render_lang() {
  local code="$1" voice="$2" text="$3"
  local stem
  if [ "$code" = "en" ]; then stem="source"; else stem="dubbed_${code}"; fi

  local aiff="${OUT_DIR}/${stem}.aiff"
  local wav="${OUT_DIR}/${stem}.wav"
  local mp4="${OUT_DIR}/${stem}.mp4"
  local srt="${OUT_DIR}/${stem}.srt"

  local prerendered="${OUT_DIR}/${stem}.src.wav"
  AUDIO_SOURCE="$voice"
  if [ -f "$prerendered" ]; then
    AUDIO_SOURCE="omnivoice"
    ffmpeg -y -loglevel error -i "$prerendered" -ar 44100 -ac 1 "$wav"
  else
    say -v "$voice" -o "$aiff" "$text"
    ffmpeg -y -loglevel error -i "$aiff" -ar 44100 -ac 1 "$wav"
    rm -f "$aiff"
  fi

  # Visual: showwaves p2p mode over a dark gradient with a colored line.
  # `nullsrc` + `geq` would let us make a static gradient backdrop, but
  # simpler is `color` with overlay'd waveform.
  ffmpeg -y -loglevel error \
    -i "$wav" \
    -filter_complex "[0:a]showwaves=s=1280x720:mode=p2p:rate=30:colors=0xf3a5b6[wave]; \
                     color=c=0x1d2021:s=1280x720:d=60[bg]; \
                     [bg][wave]overlay=format=auto,format=yuv420p,trim=duration=$(ffprobe -v error -show_entries format=duration -of default=nw=1:nk=1 "$wav")[v]" \
    -map "[v]" -map 0:a \
    -c:v libx264 -crf 28 -preset medium \
    -c:a aac -b:a 96k -ac 1 \
    -shortest \
    "$mp4"

  rm -f "$wav"

  # Single-cue SRT — entire utterance as one block, "good enough" for the
  # demo player which shows it as a caption strip rather than karaoke.
  local dur
  dur=$(ffprobe -v error -show_entries format=duration -of default=nw=1:nk=1 "$mp4")
  local end_ts
  end_ts=$(awk -v d="$dur" 'BEGIN { h=int(d/3600); m=int((d%3600)/60); s=d-int(d/60)*60; printf "%02d:%02d:%06.3f", h, m, s }' | tr '.' ',')
  cat > "$srt" <<EOF
1
00:00:00,000 --> ${end_ts}
${text}
EOF

  local size
  size=$(du -h "$mp4" | awk '{print $1}')
  echo "  ✓ ${stem}.mp4 ($size, ${AUDIO_SOURCE})"
}

if [ -f "${OUT_DIR}/source.src.wav" ]; then
  RENDERED_BY="omnivoice engine + ffmpeg showwaves"
else
  RENDERED_BY="macOS say + ffmpeg showwaves"
fi

echo "── Source video (English) ────────────────────────────────"
render_lang en  Samantha "$EN_SCRIPT"

echo ""
echo "── Dubbed videos (4 languages) ───────────────────────────"
render_lang es  Mónica   "$ES_SCRIPT"
render_lang fr  Thomas   "$FR_SCRIPT"
render_lang zh  Tingting "$ZH_SCRIPT"
render_lang ja  Kyoko    "$JA_SCRIPT"

echo ""
echo "── Manifest ──────────────────────────────────────────────"
# bash 3.2 (default on macOS) lacks ${var@Q}; pass scripts as env vars to
# Python so escaping of unicode + quotes is handled correctly.
OUT_DIR="$OUT_DIR" RENDERED_BY="$RENDERED_BY" \
EN_SCRIPT="$EN_SCRIPT" ES_SCRIPT="$ES_SCRIPT" FR_SCRIPT="$FR_SCRIPT" \
ZH_SCRIPT="$ZH_SCRIPT" JA_SCRIPT="$JA_SCRIPT" \
python3 - <<'PY'
import json, datetime, os
out = os.path.join(os.environ["OUT_DIR"], "manifest.json")
manifest = {
  "version": "0.3.0",
  "rendered_by": os.environ.get("RENDERED_BY", "macOS say + ffmpeg showwaves"),
  "rendered_at": datetime.datetime.now(datetime.timezone.utc).strftime("%Y-%m-%dT%H:%M:%SZ"),
  "license": "MIT (synthetic, no third-party IP)",
  "source": {
    "code": "en", "label": "English",
    "video": "source.mp4", "srt": "source.srt",
    "script": os.environ["EN_SCRIPT"],
  },
  "dubbed": [
    {"code":"es","label":"Español","video":"dubbed_es.mp4","srt":"dubbed_es.srt","dir":"ltr","script":os.environ["ES_SCRIPT"]},
    {"code":"fr","label":"Français","video":"dubbed_fr.mp4","srt":"dubbed_fr.srt","dir":"ltr","script":os.environ["FR_SCRIPT"]},
    {"code":"zh","label":"中文","video":"dubbed_zh.mp4","srt":"dubbed_zh.srt","dir":"ltr","script":os.environ["ZH_SCRIPT"]},
    {"code":"ja","label":"日本語","video":"dubbed_ja.mp4","srt":"dubbed_ja.srt","dir":"ltr","script":os.environ["JA_SCRIPT"]},
  ],
}
with open(out, "w", encoding="utf-8") as f:
    json.dump(manifest, f, ensure_ascii=False, indent=2)
PY
echo "  ✓ manifest.json"

echo ""
du -sh "$OUT_DIR" | awk '{print "  Bundle: " $1}'
echo "Done."