[FFmpeg-devel] [PATCH] Use custom option to specify WebVTT kind

Matthew Heaney matthewjheaney at google.com
Wed Jun 12 22:00:11 CEST 2013


On Wed, Jun 12, 2013 at 12:32 AM, Clément Bœsch <ubitux at gmail.com> wrote:

>
> I don't find anything about that in the WebVTT specifications. It seems to
> be specific to the way WebVTT is supposed to be muxed in WebM, which is
> basically saying only:
>
>    [...] where kind is one of SUBTITLES, CAPTIONS, DESCRIPTIONS, or
> METADATA.
>
> I would like to know more about each of them before introducing them into
> the API (typically, how do you differentiate subtitles from captions?).
>
>
It's defined in HTML5, 4.8.10.xx, Timed text tracks:

http://www.w3.org/TR/2011/WD-html5-20110113/video.html#timed-text-tracks

and in HTML5 4.8.9, The Track Element:

http://dev.w3.org/html5/spec-preview/the-track-element.html

See also the WebVTT-In-WebM spec:

http://wiki.webmproject.org/webm-metadata/temporal-metadata/webvtt-in-webm

The kind of an out-of-band text track is specified in HTML5 explicitly,
using the kind attribute of the Track tag.  In-band text tracks (as you
find in WebM) specify the kind using a combination of track type and codec
id.

-Matt


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