Facebook Feed video captions: burn them onto a clip with no speech

Meta's Facebook Feed video ad page marks video captions as optional but recommended. Sume's POST /v1/video-captions transcribes speech by default, so a silent product clip fails with caption_no_speech; pass authored cues with text, start and end to burn copy without speech-to-text.

Why does my silent product clip fail captioning?

The captions docs say speech-to-captions, from script_text or from speech-to-text when it is omitted, needs audible speech. A silent clip fails as caption_no_speech with next_action: use_overlay_captions, which is a specific failure and not a generic policy rejection. A Timeline render with audio.mode set to silence produces exactly that kind of clip.

How do I burn authored copy instead?

Send cues (or segments), each with text, start and end. That is the authored overlay path and it skips speech-to-text. video_url must be a public HTTPS URL. style is optional; leave it off and the wording decides (slam for Latin text).

curl -X POST https://api.sume.com/v1/video-captions \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: feed-captions-001" \
  -d '{
    "video_url": "https://example.com/candle-silent.mp4",
    "cues": [
      { "text": "Hand-poured soy candle", "start": 0.0, "end": 2.5 },
      { "text": "Burns for 40 hours", "start": 2.5, "end": 5.0 }
    ]
  }'

Which case needs which route?

Match the clip to the route.

What are the limits of this answer?

Meta lists captions as optional, so nothing here is required to pass review. The captions docs describe the job, not how a burned-in caption sits inside Meta's placement; check the result in Meta's ad preview. The hard-coded times above are placeholders, so set them to the length of your clip.