[FFmpeg-devel] Add mpeg user_data CEA-608/708 extraction.

Baptiste Coudurier baptiste.coudurier
Thu Apr 15 01:04:23 CEST 2010

On 04/11/2010 02:24 PM, Michael Niedermayer wrote:
> On Sun, Apr 11, 2010 at 10:25:07PM +0200, Laurent Aimar wrote:
>> Hi,
>> On Sun, 2010-04-11 at 15:49 -0400, Ronald S. Bultje wrote:
>>> But is it part of a generic video frame then? I mean, you appear to
>>> put this "thing" in AVPicture, suggesting that it can be part of any
>>> picture, be that Sorensen-3, MPEG-4, Theora or raw YUV video.
>>> My suggestion, again, would be to put it in its own stream, so that
>>> packets have timestamps and the stream has a mediatype ("CEA-[67]08"),
>>> which is a subtitle stream with fonts, glyphs, windows etc. The MPEG-2
>>> demuxer would need to split it, and the MPEG-2 muxer would re-join it.
>>> Your application wouldn't know any better than if it were a Matroska
>>> stream with SSA subtitles.
>>   Closed Captions data are usually embed inside the user data of the
>> elementary video streams. This make it very hard to extract them at the
>> demuxer level:
>>   - You have to parse the video stream (mpeg-2 and h264) to extract them
>>   - You have to reorder them as the video decoder would do for the
>> associated video frame.
>>   - You have to know the timestamp of the associated video frame to give
>> them one.
> yes, the design sucks and it doesnt seem we can fix that. so in AVFrame
> it will have to go unless someone manages to cleanly put them in a
> seperate stream but i dont see how that would be possible

I agree.

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