SCC caption file: YouTube's preferred format vs Sume burn-in
YouTube calls .scc its preferred caption file format. Sume burns captions into the video and takes no SRT upload. When each one is right, plus a workflow.
What YouTube says about .scc
The YouTube Help page on subtitle and closed caption file types calls .scc its preferred file format and ties it to CEA-608 captions. It lists .srt and .sbv as basic formats with no style markup, .vtt with positioning supported and styling limited to bold, italic and underline, and .ttml with styling and positioning. It also lists .smi, .sami, .lrc and .stl, the last being EBU-STL.
The point of a caption file is that the viewer's player draws the text and the viewer can turn it off.
What Sume produces
Sume's Video captions endpoint does a different job. It burns the text into the video pixels, so the captions are part of the picture. There is no caption-file output and SRT uploads are unsupported; you pass phrase-level cues instead.
| Question | Caption file (.scc, .vtt, .srt) | Burned in with Sume |
|---|---|---|
| Viewer can turn off | Yes | No |
| Styling | Depends on format and player | Styles, colors, fonts and motion you choose |
| Platform auto-handles accessibility | Yes | Not as a text track |
| Works in autoplay muted feeds | Needs the platform to show tracks | Always visible |
Do both
For YouTube you often want both: burned-in styled captions for the muted autoplay look, and an uploaded caption file for accessibility and search. They do not conflict as long as the burned-in text is not duplicated by an on-by-default track.
- Generate word or sentence timings with STT.
- Burn styled captions with Sume for the video you publish.
- Write the same text as a caption file in the format the platform wants.
- Upload the file as a separate track, left off by default if the burned-in text would double up.
A note on .scc
CEA-608 is a broadcast caption format, and writing it by hand is error-prone. Sume does not produce it. If a broadcaster requires it, export from a captioning tool that knows the spec and use Sume's sentence segments as the timed text to feed it.
Which file type to export for which platform
YouTube's page is the only platform reference used here. It lists .srt and .sbv as basic, .vtt as positioned with limited styling, .ttml as styled and positioned, and .scc as preferred. For a platform you have not read the help page of, check its upload format before generating anything.
Keep one source of truth: the timed text. Everything else, the burn-in and each file type, is an export from it.
Takeaway
Use .scc when a platform or broadcaster wants a caption file. Use Sume's burn-in when the captions must be visible no matter what. For many releases, ship both.
Sources
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