WebVTT

Main differences from SubRip

• WebVTT's first line starts with WEBVTT after the optional UTF-8 byte order mark
• There is space for optional header data between the first line and the first cue
• Timecode fractional values are separated by a full stop instead of a comma
• Timecode hours are optional
• The frame numbering/identification preceding the timecode is optional
• Comments identified by the word NOTE can be added
• Metadata information can be added in a JSON-style format
• Chapter information can be optionally specified
• Only supports extended characters as UTF-8
• CSS in a separate file defined in the companion HTML document for C tags is used instead of the FONT element
• Cue settings allow the customization of cue positioning on the video

Compatibility

Firefox implemented WebVTT in its nightly builds (Firefox 24), but initially it was not enabled by default. The feature had to be enabled in Firefox by going to the "about:config" page and setting the value of "media.webvtt.enabled" to true. YouTube began supporting WebVTT in April, 2013. As of July 24, 2014, Mozilla has enabled WebVTT on Firefox by default.

Subtitles in a .vtt file show online, but not when stored on a local drive.

Example of WebVTT format

A sample file from the W3C captioning Roger Bingham interviewing Neil deGrasse Tyson (https://www.youtube.com/watch?v=P_Um2VdIKmA):

WEBVTT

00:11.000 -- 00:13.000 We are in New York City

00:13.000 -- 00:16.000 We're actually at the Lucern Hotel, just down the street

00:16.000 -- 00:18.000 from the American Museum of Natural History

00:18.000 -- 00:20.000 And with me is Neil deGrasse Tyson

00:20.000 -- 00:22.000 Astrophysicist, Director of the Hayden Planetarium

00:22.000 -- 00:24.000 at the AMNH.

00:24.000 -- 00:26.000 Thank you for walking down here.

00:27.000 -- 00:30.000 And I want to do a follow-up on the last conversation we did.

00:30.000 -- 00:31.500 align:right size:50% When we e-mailed—

00:30.500 -- 00:32.500 align:left size:50% Didn't we talk about enough in that conversation?

00:32.000 -- 00:35.500 align:right size:50% No! No no no no; 'cos 'cos obviously 'cos

00:32.500 -- 00:33.500 align:left size:50% Laughs

00:35.500 -- 00:38.000 You know I'm so excited my glasses are falling off here.

Other features

In June 2013, an example was added to the specification that included a new "region" setting. This feature is supported since Firefox 59 and Safari 14.1 (14.5 on iOS) but not in any other browser.

References

References

1. "WebSRT".
2. [http://www.whatwg.org/specs/web-apps/current-work/websrt.html WebSRT], from the WHATWG HTML draft specification, retrieved 2010-10-14
3. "HTML5".
4. "WebVTT cue settings". W3C.
5. (23 August 2012). "WebVTT support in browser". W3C.
6. "WebVTT Styling". JWPlayer.
7. "Implement the track element".
8. "Caption File - YouTube Help".
9. "Firefox 31 Release Notes".
10. (4 April 2019). "WebVtt: The Web Video Text Tracks Format". The World Wide Web Consortium.
11. "Added region example to Introduction section under "Other features" – GitHub commit details".
12. (20 July 2025). "VTTCue.region - Web APIs | MDN".