WebVTT

WebVTT

Filename extension	not specified
Internet media type	text/vtt
Developed by	W3C
Initial release	10 August 2010[1]
Type of format	Timed text
Extended from	SRT
Standard	W3C WebVTT
Open format?	Yes

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).^[2] It shared the .srt file extension and was "broadly based on" (parts of) the SubRip format, though not fully compatible with it.^[3] The prospective format was later renamed WebVTT.^[4][5] 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.

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^[6]

Compatibility

Browser Support^[7]

BROWSER	CUE POSITIONING	CUE TEXT TAGS	CSS STYLING
Firefox for Desktop	31+	31+	-
Chrome for Desktop	35+	35+	35+
Safari for Mac	7+	7+	7+
Opera for Desktop	22+	22+	22+
Internet Explorer for Windows	-	-	-
Safari for iOS	8+	8+	8+
Stock Browser for Android	5.0+	5.0+	5.0+
Chrome for Android	35+	35+	35+
Firefox for Android	32+	32+	-
Internet Explorer for Winphone	-	-	-

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.^[8] YouTube began supporting WebVTT in April, 2013.^[9] As of July 24, 2014, Mozilla has enabled WebVTT on Firefox by default.^[10]

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.^[11] As of February 2015, however, no player included support for this feature.

References

1. "WebSRT". Archived from the original on 2010-08-16. Retrieved 2015-02-12.
2. "WebVTT versus TTML: XML considered harmful for web captions?". Retrieved 16 February 2015.
3. WebSRT, from the WHATWG HTML draft specification, retrieved 2010-10-14
4. Kennedy, Antony; de Leon, Inayaili (2011). Pro CSS for High Traffic Websites. Apress. ISBN 978-1-4302-3288-9.
5. Pfeiffer, Silvia (June 27, 2011). "Recent developments around WebVTT".
6. "WebVTT cue settings". W3C. Retrieved 11 February 2015.
7. "WebVTT Styling". JWPlayer. Retrieved 23 February 2015.
8. "Implement the track element".
9. "Caption File - YouTube Help".
10. "Firefox 31 Release Notes".
11. "Added region example to Introduction section under "Other features" – GitHub commit details".

External links

• VTTandSRT, small free french software to convert a .VTT subtitles file into a .SRT subtitles file (and conversely).