What is VTT?

VTT –VTT Stands for Video Text Tracks A method of closed captioning that syncs the video’s speed with the text’s speed using time stamps. See also: Closed Captioning and Subtitles.

WebVTT (Web Video Text Tracks) is a World Wide Web Consortium (W3C) standard for showing coordinated text regarding the HTML5 <track> component. The early drafts of its determination were composed by WHATWG in 2010 after conversations about what subtitle configuration ought to be upheld by HTML5—the primary alternatives being the moderately adult, XML-based Timed Text Markup Language (TTML) or an altogether new however more lightweight standard dependent on the broadly utilized SubRip design. An official choice was for the new norm, at first called WebSRT (Web Subtitle Resource Tracks) It shared the .srt record expansion and was extensively founded on the SubRip design, however not completely viable with it The imminent organization was later renamed WebVTT. In the January 13, 2011 variant of the HTML5 Draft Report], the<track> tag was presented and the detail was refreshed to archive WebVTT signal text delivering rules.[6] The WebVTT particular is still in the draft stage however the essential highlights are as of now upheld by every single significant program.

History of VTT

In 2004 a group of W3C members decided to split off from the W3C HTML specification and to push HTML outside of, but in close collaboration with the W3C. The Web Hypertext Application Technology Working Group (WHATWG) was set up with the goal to “create technical specifications that are intended for implementation in mass-market web browsers, in particular, Safari, Mozilla, and Opera”.

Although WebVTT is currently specified by the W3C Web Media Text Tracks Community Group, the decision to use SRT as its base had been taken by the WHATWG, and the initial specification has been written with Ian Hickson as responsible editor. Priorities for the choice of a timed text format included: simplicity, compatibility with existing players and integration into the HMTL5 specification effort


A simple two-line subtitle would be expressed in WebVTT as a text cue:

00:00:00.000 --> 00:00:02.000
This is a subtitle
on two lines

The delimiter for begin and end timecodes is the string “–>”. A character sequence representing a newline (LF, CR, or CRLF) separates the timing information from subtitle text and breaks a subtitle text line.[6]

WebVTT does not use a formal grammar to describe the syntax but a sequence of rules written in normative prose. A reduced definition of the text cue shown in the example would be:

A WebVTT timestamp representing the start time offset of the cue.
A WebVTT timestamp representing the end time offset of the cue.
A WebVTT line terminator
Zero or more WebVTT cue text span, representing the text of the cue each optionally separated from the next by a WebVTT line terminator.


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