[theora-dev] using Kate for WebVTT encapsulation

Silvia Pfeiffer silviapfeiffer1 at gmail.com
Mon Apr 11 17:44:42 PDT 2011

(sending this publicly so the discussion about this is in the open)

Hi OggK, all,

OggK, you've probably seen that the bug in Firefox for adding Kate
support has been closed as WONTFIX:

I've just posted a reply there mentioning how I envisage in-band
WebVTT support to be provided through Kate. I want to ask your

In case you haven't heard about WebVTT yet, it's the time-aligned text
format that has been developed by the WHATWG as the baseline text
format for HTML5 media elements, see
http://www.whatwg.org/specs/web-apps/current-work/webvtt.html .
Also see http://www.whatwg.org/specs/web-apps/current-work/multipage/video.html#the-track-element
for how to include it with a audio or video element.

My idea is that - because WebVTT is so similar to SRT - it would be
simple to support WebVTT in Ogg by encapsulating it in a Kate track
and making sure that it can be extracted again without loss of
information through the kate libraries.

There would only be a few changes necessary:
* WebVTT has a header which needs to be parsed and re-created.
* Also, there is a suggestion for inclusion of name-value Metadata at
the top right after the header, which we'd want to retain (maybe in a
header or a first packet).
* Then there are cue settings, which are position modifiers on each
cue (segment of timed text). They need to be recreated, too.

The marked-up text inside cues needs to be retrieved unchanged.

For an old, but still mostly correct explanation with examples of some
of the things see:
http://annodex.net/~silvia/tmp/WebSRT/ (WebSRT got renamed to WebVTT)
and for something a bit newer see:

I'm just wondering what you think about this kind of approach.


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