SubRip is the interchange format. Almost every editor, caption vendor and freelancer can produce or ingest a .srt. The structure is four parts per cue: an integer index, a timestamp pair joined by -->, the text, a blank line. Times look like 00:00:01,000 — comma, not a full stop. That is the whole spec most people ever need.
What it cannot do is the reason WebVTT exists. There is no official way to place a cue, colour a word, or mark a speaker beyond writing it into the text. Karaoke-style word highlight is not an SRT feature; it is a burned-in look. If a client asks for 'styled SRT' they usually mean a burned-in MP4 plus a plain .srt for archives, or they mean WebVTT and have the wrong extension in the brief.
Use SRT as the source of truth for words and times, then burn a look in. Shift a whole track with a constant offset when an intro was trimmed; if captions drift further out as the video runs, that is a frame-rate mismatch and an offset will not fix it. Versely's free converters and the line-length checker operate on this file, not on pixels.
In practice
- Treat .srt as words and times, not as the finished caption look.
- When a platform wants a track, send SRT or WebVTT; when a feed wants a caption, burn it in.
- A constant offset fixes a track that is uniformly early or late. Progressive drift is a different bug.
The mistake to avoid
Handing a client a .srt and a silent MP4 for a TikTok. The feed will play the picture. It will not play the sidecar.
Where you will run into it
- AI Caption Generator — Drop a video, get timed captions. Free, on your device, no upload.
Related terms
WebVTT
WebVTT is the web-native caption file: a .vtt sidecar with cues, timestamps, and optional positioning and styling the player may honour.
Closed captions
Closed captions are a separate subtitle track the player draws, which the viewer can switch off and which each platform styles itself.
Caption timing
Caption timing is when each line appears and disappears relative to the speech — the clock, not the words and not the look.
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.
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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