compose_video_has_no_audio: a silent clip under a still on Sume

What does compose_video_has_no_audio mean?

Timeline compose stacks or overlays one still on one video. When the video layer has no audio track, the job completes but adds the warning compose_video_has_no_audio to warnings[]. It is a soft warning, not a failure, and compose does not invent sound: the output is as silent as the input.

Is it a problem?

Only if you wanted sound. A silent product loop under a price card is fine for autoplaying feeds. For a shop page with a voice, you need an extra step. Output length also comes from the video layer, so a clip with no audio gives a silent result of exactly that length, up to 300 seconds.

Check before you pay for polish: probe the clip with video inspect, which returns a probe of the streams.

How do I add a voice-over?

Run a Timeline render over the compose output. The render takes an audio object, a URL plus duration_seconds (1 to 1800), and one or more video[] slots. Put the compose video_url in slot one with start: 0. Compose costs $0.02 and the render $0.10 per output minute, so a 30 second voiced banner is $0.12.

Sound design can wait: the order is compose first, voice second.

curl -X POST https://api.sume.com/v1/timeline-1.0/render \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: banner-sku1001-vo" \
  -d '{"audio":{"url":"https://media.sume.com/artifacts/artf_demo/vo.wav","duration_seconds":30},
       "video":[{"source_url":"https://media.sume.com/artifacts/artf_demo/composed.mp4",
                 "start":0,"duration":30}]}'

Where is the first step explained?

The stack layout for a price card is in the Cyber Monday half banner post.