[Ffmpeg-devel] [RFC] rtjpeg and NuppelVideo decoder/demuxer

Rich Felker dalias
Mon Feb 13 05:05:31 CET 2006

On Tue, Feb 07, 2006 at 09:04:21PM +0100, Reimar D?ffinger wrote:
> Hi,
> the attached patch adds $subject to ffmpeg (well, actually it is a patch
> against MPlayer with libav* and untested on ffmpeg itself).
> The reason I'm posting this is that there is one thing I dislike but
> I do not know a good solution.
> The problem is, codec specific data, like the quantization tables for
> rtjpeg are "normal" packets, and at least the MPlayer demuxer passes
> them around as such.
> I very much prefer to have them as extradata, also because otherwise
> with MPlayer's approach there actually aren't any real keyframes - no
> single video packet contains _all_ the data to decode a full frame.
> Also, when the packet contains codec data, it does not encode any frame.
> Is there a way the codec should indicate this?
> _But_ if the decoder only supported the extradata approach it would not
> work with MPlayer's demuxer or files that were remuxed into AVI by it.

Such files (remuxed into avi) are hopelessly invalid, since timestamps
will be totally wrong with these nonsense non-frame packets. Feel free
not to support them.

> Worse, it would be impossible to decode correctly files where the
> quantization tables change somewhere in between (I assume that extradata
> is not allowed to be changed?).

If they're allowed to change, they need to be prepended onto the
subsequent (key)frame and no other frames marked key. Otherwise they
should be extradata.

And whoever designed this shit needs Diego to ram a truckload of cola
through the front of his house...


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