Kalpana Kalpana (Editor)

WebVTT

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Filename extension
  
not specified

Developed by
  
W3C

Extended from
  
SRT

Internet media type
  
text/vtt

Type of format
  
Timed text

Initial release
  
10 August 2010; 6 years ago (2010-08-10)

WebVTT (Web Video Text Tracks) is a W3C standard for displaying timed text in connection with the HTML5 <track> element. The early drafts of its specification were written by WHATWG in 2010, after discussions about what caption format should be supported by HTML5, the main options being the relatively mature, XML-based TTML or an entirely new but more lightweight standard based on the popular SRT format. The final decision was for the new standard, initially called WebSRT (Web Subtitle Resource Tracks). It shared the .srt file extension and was "broadly based on" (parts of) the SubRip format, though not fully compatible with it. The prospective format was later renamed WebVTT. In the January 13, 2011 version of the HTML5 Draft Report, the <track> tag was introduced and the specification was updated to document WebVTT cue text rendering rules. The WebVTT specification is still in draft stage but the basic features are already supported by all major browsers.

Contents

Main differences from .srt

  • 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
  • Metadata frames identified by the word NOTE can be added
  • 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 tag
  • 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.

    Example of WebVTT format

    WEBVTT 00:09.000 --> 00:11.000 <v Roger Bingham>We are in New York City 00:11.000 --> 00:13.000 <v Roger Bingham>We are in New York City 00:13.000 --> 00:16.000 <v Roger Bingham>We're actually at the Lucern Hotel, just down the street 00:16.000 --> 00:18.000 <v Roger Bingham>from the American Museum of Natural History 00:18.000 --> 00:20.000 <v Roger Bingham>And with me is Neil deGrasse Tyson 00:20.000 --> 00:22.000 <v Roger Bingham>Astrophysicist, Director of the Hayden Planetarium 00:22.000 --> 00:24.000 <v Roger Bingham>at the AMNH. 00:24.000 --> 00:26.000 <v Roger Bingham>Thank you for walking down here. 00:27.000 --> 00:30.000 <v Roger Bingham>And I want to do a follow-up on the last conversation we did. 00:30.000 --> 00:31.500 align:end size:50% <v Roger Bingham>When we e-mailed— 00:30.500 --> 00:32.500 align:start size:50% <v Neil deGrasse Tyson>Didn't we talk about enough in that conversation? 00:32.000 --> 00:35.500 align:end size:50% <v Roger Bingham>No! No no no no; 'cos 'cos obviously 'cos 00:32.500 --> 00:33.500 align:start size:50% <v Neil deGrasse Tyson><i>Laughs</i> 00:35.500 --> 00:38.000 <v Roger Bingham>You know I'm so excited my glasses are falling off here.

    Unsupported features

    In June 2013 an example was added to the other features section of the specification that included a new "region" setting. As of February 2015, however, no player included support for this feature.

    References

    WebVTT Wikipedia
    (Text) CC BY-SA