[FFmpeg-devel] [PATCH] Fix return value for incomplete H264 frame packets

[Michael Niedermayer]

On Tue, Aug 24, 2010 at 12:24:52AM +0200, P?sztor Szil?rd wrote:
> Carl Eugen Hoyos:
> > Michael Niedermayer <michaelni <at> gmx.at> writes:
> >> either way, iam not sure what actual problem people are trying to solve
> >> with
> >> this EAGAIN error code ?
> > 
> > Always the same problem;-)
> > PAFF streams do not have correct A/V sync with MPlayer's native MPEG-2 TS
> > demuxer (mpegts), and we can't make demuxer lavf the default because of
> > FFmpeg
> 
> Actually it's a lot more than "not having correct A/V sync", because
> what may seem sometimes correct A-V sync is only the sync algorithm
> dragging the severely lagged video forward again and again, making
> playback very jerky at best. Most samples are broken with both
> demuxers.
> 
> The basic problem is that ATM there's no way to recognize if
> no picture is returned because there's no data on purpose where
> the player should wait a frametime, or because it's only a first
> field where the second field should be decoded immediately.
> Thus player applications can't keep sync because they don't have
> enough information to do so.

H264 & H222 describe when each field should be displayed. Or in other words
they decribe how to calculate a timestamp for each field
about 1/4 of the code needed on the lavf side has been implemented
until the remaining code is implemented and it all is free of bugs it will
not always work

your patch does not move us closer to that. read the spec please
there is no alternative, frame times are not neccessarily constant for
example thus your hack clearly is not sufficient
also the timestamps can and should be calculated in the parser thus
there should be no need to change the decoder except if its buggy or
to factor code out.

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Let us carefully observe those good qualities wherein our enemies excel us
and endeavor to excel them, by avoiding what is faulty, and imitating what
is excellent in them. -- Plutarch
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