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

Michael Niedermayer michaelni
Wed Feb 8 02:07:48 CET 2006


first, i didnt review the patch yet, just commenting on the mail...

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.
> 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?).

yes, if the tables may change they _must_not_ be in extradata! you should
somehow figure out if they are truly constant or not (RTFS/RTFM/ask author)


> And one last thing concerning the demuxer: since nuv files contain
> timestamps given in milliseconds for each packet, I set r_frame_rate to
> the fps and used av_set_pts_info(vst, 32, 1, 1000);
> Is this the correct way to do it? It is a bit annoying, since this way

hmm you shouldnt need to set r_frame_rate, lavf should figure that out
for you ...

> MPlayer will not display the true framerate but 1000 fps instead...

-> bug, someone needs 10l, probably myself



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