Teach an English word as a video supercut

Turn one English word into a self-contained HLS lesson:

intro.ts  (word /IPA/ · 中文 gloss · usage + Volcano TTS)
   ⋯ EXT-X-DISCONTINUITY
[supercut] every season2 clip where the word is spoken  (search-app /api/playlist, COS URLs)
   ⋯ EXT-X-DISCONTINUITY
cta.ts    (关注王建硕 + Volcano TTS)
= search-app/out/<word>.m3u8

No MP4 is burned — only the two cards are rendered as tiny .ts, re-encoded to match the supercut's codec so they play in any HLS player.

Prerequisites (check once)

• ffmpeg / ffprobe on PATH (Homebrew).
• Python volcengine SDK (declared in mira requirements.txt, used for TTS):

python3 -c "import volcengine". If missing, ask the user to allow pip3 install volcengine==1.0.58 (it's a pinned repo dependency).

• The deployed search-app at https://search-app-three-kappa.vercel.app

(default). Override with SEARCH_APP_BASE=http://localhost:3000 if running locally (needs Node ≥ 23.6 + npm start).

Steps

1. Get the word. A single English word (or short phrase). If the user gave

a sentence, pick the target word.

1. Write the mini-lesson JSON. YOU (Claude) author it — no dictionary API.

Keep it accurate and concise. Save to a temp file, e.g. /tmp/lesson.json:

   {
     "word": "love",
     "ipa": "/lʌv/",
     "pos": "v. / n.",
     "gloss": "爱，热爱",
     "usage": "下面是它在真实电影里的说法",
     "tts_text": "love. 爱。"
   }

• tts_text is read aloud over the intro card — keep it to the word + a

short 中文 gloss (Volcano reads mixed English/中文 fine).

• usage is one short line shown on the card (≤ ~20 chars renders best at

low resolutions).

1. Build it:

   cd /Users/jianshuo/code/mira/search-app
   python3 scripts/build_lesson.py --word love --lesson /tmp/lesson.json

Useful flags: --speaker zh_female_qingxin (default), --limit 300 (max clips), --no-tts (silent cards), --base <url>, --out <dir>.

1. Report the printed output path (search-app/out/<word>.m3u8) and the

clip count. The .m3u8 plus its sibling <word>.intro.ts / <word>.cta.ts are the deliverable; out/ is git-ignored.

Notes

• If the word has no clips, the script exits with "no clips match" and writes

nothing — tell the user and suggest a more common word.

• Intro/CTA are encoded to the FIRST supercut segment's resolution/codec/fps so

the first discontinuity needs no decoder re-init (avoids bufferAppendError).

• To play locally: ffplay search-app/out/<word>.m3u8, or serve the out/

folder over HTTP and open in any HLS player (Safari plays .m3u8 natively).