[FFmpeg-devel] [PATCH] Matroska demuxer adds WebVTT support

Matthew Heaney matthewjheaney at google.com
Wed Jul 31 21:26:20 CEST 2013

On Fri, Jul 19, 2013 at 3:12 PM, Nicolas George <
nicolas.george at normalesup.org> wrote:

> I can state another argument, but I believe it boils down to the same basic
> principles: the reasons that made you choose this particular format to
> store
> in Matroska probably apply to AVPacket as well. Sure, AVPacket is slightly
> more powerful than Matroska, with its side data and stuff. But the way I
> see
> it, side data is for situations where the container features really exceeds
> the packet model, while WebVTT-in-Matroska fits the model perfectly.

To summarize my task:

(0) Remove the webvtt side data enumeration values declared in avcodec.h.

(1) Rewrite the webvtt decoder to strip out the timestamp from the original
webvtt cue, and use that result as the value of the avpacket data, such
that we don't use side data anymore.

(2) Rewrite the matroska decoder to detect the presence of subtitle track,
and use the Matroska frame as the value of the avpacket data.

(3) Rewrite the webvtt encoder to use the new format of the avpacket
(instead of the current format, which uses side data).

(4) Rewrite the webm encoder to use the new format of  the avpacket when
writing a subtitle track.

Can someone confirm whether my understanding of the task is correct?


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