[FFmpeg-cvslog] h264dec: Dont display trash before a keyframe.

Michael Niedermayer michaelni at gmx.at
Sun Sep 18 07:22:57 CEST 2011


On Sun, Sep 18, 2011 at 02:19:32AM +0200, Reimar Döffinger wrote:
> On 17 Sep 2011, at 22:02, git at videolan.org (Michael Niedermayer) wrote:
> > ffmpeg | branch: master | Michael Niedermayer <michaelni at gmx.at> | Sat Sep 17 19:59:48 2011 +0200| [a64b028aeb6579636e578ceb73f69b468bddb2f0] | committer: Michael Niedermayer
> > 
> > h264dec: Dont display trash before a keyframe.
> > Fixes Ticket472
> > This may (or may not) cause problems with files that have no keyframes.
> > Plese open a bugreport or mail me if you have a file for which this fails.
> 
> I strongly dislike this. The user might prefer that "trash" (which for some streams might be fairly good quality, and for streaming trash is a whole lot better than having to wait several seconds before anything happens at all), and FFmpeg shouldn't just decide what is better.
> Even more since I think H.264 is now the only codec that does this, IMO this is an inconsistent mess.

> There are many simple and more useful ways of solving this, I suggested several like adding an error flag to the context or to AVFrame but nobody showed real interest, instead it's such a "oh, let's break it for the _other_ half of users I instead" solution :-(

iam in favor of a "i want to see all frames" flag
that way the decoder can skip decoding non reference frames and frames
prior to the first keyframe/recovery point when it knows the user
doesnt want to see them anyway. A per frame flag that tells the user
"this may be broken looking" requires the decoder to decode all.
that said these solutions arent exclusiv both could be done ...

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

Many that live deserve death. And some that die deserve life. Can you give
it to them? Then do not be too eager to deal out death in judgement. For
even the very wise cannot see all ends. -- Gandalf
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