A .vtt file holds WebVTT (Web Video Text Tracks) captions, the subtitle format browsers use with the HTML5 track element. When you save captions from a streaming site, an online course or a YouTube video, this is usually what you get. It starts with the word WEBVTT and writes times with a dot, like 00:01:02.345.
WebVTT grew out of SRT but added everything a web player needs: cue settings that place a line at the top or side of the frame, CSS styling blocks, regions for scrolling captions, NOTE comments, speaker (voice) tags and, in auto-generated captions, a timestamp on almost every word.
That extra layer is exactly what trips up TVs, USB players and editing software. Many of them only understand plain SRT, and the ones that open VTT anyway may show raw tags, ignore the file or stop at the header.
This converter keeps the text and timing and translates the rest. The header, NOTE, STYLE and REGION blocks and the cue settings are dropped; speaker, class, language and ruby tags are removed; word-level timestamps disappear. Italic, bold and underline survive, and a cue placed at the top of the frame becomes the SRT code {\an8} so it stays out of the way of on-screen text.
- Full name
- Web Video Text Tracks (WebVTT)
- Standard
- W3C specification, first drafted at WHATWG around 2010 under the name WebSRT
- Extension and type
- .vtt, text/vtt
- Time format
- 00:01:02.345 (dot, hours optional) versus 00:01:02,345 in SRT
- Lost in SRT
- Positions, CSS styles, regions, notes, speaker names, word timings
- Kept in SRT
- Text, start and end times, italic, bold and underline, top placement as {\an8}