[FFmpeg-devel] [PATCH 3/4] ffmpeg: with filter_complex, avoid random in<->out mapping.

Michael Niedermayer michaelni at gmx.at
Mon Jun 4 18:06:33 CEST 2012

On Mon, Jun 04, 2012 at 05:25:05PM +0200, Nicolas George wrote:
> Le septidi 17 prairial, an CCXX, Michael Niedermayer a écrit :
> > This produces the expected AV desync
> ... and it duplicates each frame.
> > PTS/2 instead of 2*PTS works fine as well and produces the expected
> > 2x speedup of the video
> No, it does not: it produces the 2× speedup bu dropping one frame out of
> two, instead of doubling the frame rate.
> > So far we have 3 cases that work before the patch and fail after the
> > patch.
> > I hope this explains my concerns i had about this patch
> So do I.
> > I surely understand your argument that it is theoretically nonsense
> > as its done but it simply works better than without that code for the
> > end user.
> I do not think that it works better: it fails in more subtle ways, that are
> harder to predict and notice. I find it better to fail hard immediately and
> let the user fix it instead of letting the user notice after possibly
> 24+ hours of encoding that the video is choppy.

The user will see a failure and have no idea on what to do. The error
messages dont tell him so how could he ?
also what about scirpts ? maybe some server side script run over
uploaded files ...

anyway, what do you suggest on how to solve this ?
as it is there are some problems which you pointed out, with the
removial of that hunk there are other problems. I dont think either
can be the final solution. And i think we are wasting both our times
by discussing around this patch. It certainly can be part of a
solution to remove this code and i dont mind that at all but i dont
think simply removing this and leaving it to the user to always have
to specify the frame rate is a good idea.


Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Those who are best at talking, realize last or never when they are wrong.
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