HTML video uses WebVTT. YouTube, many course players, and anything that ships a <track> element expect it. The file starts with a WEBVTT header, then cues whose timestamps use a full stop as the decimal (00:00:01.000) rather than SubRip's comma. That one character is the usual reason a renamed .srt fails as a .vtt.
WebVTT can carry more than words. Cue settings (line, position, size, align), regions, and a STYLE block let an author place and colour captions in the player. SubRip cannot represent any of that. Converting VTT to SRT keeps the text and the times and drops the layout — which is fine when the destination is a player that ignores layout anyway, and a loss when the caption was authored to sit off a face.
A burned-in caption is not a WebVTT file. Once the line is pixels, there is no cue to restyle. Export a .vtt when a client or a long-form platform wants a track they can toggle; burn in when the feed will never enable one. Versely's in-browser converter handles the header and the timestamp separator so you are not doing that by hand.
In practice
- Keep the WEBVTT header. A file that is only cues is not a valid .vtt.
- Use a converter rather than find-and-replace on the decimal; cue settings have no SubRip equivalent and should be dropped on purpose.
- Do not send a .vtt to a short-form scheduler and expect the caption to appear in the feed.
The mistake to avoid
Renaming .srt to .vtt. The timestamp separator and the missing header are enough for a player to reject the track.
Where you will run into it
- AI Caption Generator — Drop a video, get timed captions. Free, on your device, no upload.
Related terms
SRT
SRT is the simplest caption sidecar: numbered cues, start and end times with a comma decimal, and plain text. No styling, no positioning.
Closed captions
Closed captions are a separate subtitle track the player draws, which the viewer can switch off and which each platform styles itself.
Burned-in captions
Burned-in captions meaning: subtitles rendered into pixels, so viewers cannot turn them off or lose them on re-upload. Closed captions are a separate track.
Caption timing
Caption timing is when each line appears and disappears relative to the speech — the clock, not the words and not the look.
Hook rate
Hook rate meaning: the share of people shown a video who are still watching a few seconds in. It grades the opening, not the body.
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