Generate Captions

Purpose

Generate subtitle files from transcript segments for selected Sparks.

Current API

Caption/subtitle generation happens during render.

POST /api/jobs/:jobId/render
GET  /api/jobs/:jobId

Inputs

{
  "jobId": "string",
  "clips": [],
  "transcript": {
    "segments": []
  }
}

Outputs

Subtitle files are written beside rendered clip outputs.

{
  "jobId": "string",
  "status": "rendering_cuts"
}

Steps

1. Use transcript segments inside each Spark time range.
2. Generate ASS subtitle files.
3. Keep captions readable on vertical video.
4. Render subtitles into MP4 cuts with FFmpeg.

Rules

Do not invent words. Use transcript text for subtitles. Keep captions readable on mobile. Do not alter spoken content.