HTML and CSS Reference
a standard format for HTML5 media resources was called WebSRT and was based on SRT.
However, this effort was eventually renamed to WebVTT (Web Video Text Tracks), and is still
loosely based on the SRT format. Work in the WebVTT format is ongoing with the WHATWG
(Web Hypertext Application Technology Working Group), though there has been some moves
to also start up a W3C working group for the format.
At this time, there is no preferred format. Which you use depends on the tools you use to im-
plement the subtitles and captions.
There's also interest in the W3C in using the Timed Text Markup Language as a format for the track
files. However, this specification is more complicated than WebVTT or SRT because of its depend-
ence on XML, though there has been discussion of creating a JSON version of TTML for use with
HTML5 media resources. You can find more on TTML at http://www.w3.org/TR/ttaf1-dfxp/ , more
on the SRT format at http://www.matroska.org/technical/specs/subtitles/srt.html , and you can check
out the capabilities of the WebVTT format in an author-friendly format at http://www.delphiki.com/
The SRT format is extremely simple. SRT files are text files with a set of lines, each one a
specific subtitle. Each subtitle begins with a sequential number, followed by a timeline on a
second line, and then the subtitle text on a third line. Subtitles are separated from each other
by blank lines. From the Sintel English subtitle file:
00:01:47,250 --> 00:01:50,500
This blade has a dark past.
00:01:51,800 --> 00:01:55,800
It has shed much innocent blood.
00:01:58,000 --> 00:02:01,450
You're a fool for traveling alone,
so completely unprepared.
00:02:01,750 --> 00:02:04,800
You're lucky your blood's still flowing.