[FFmpeg-devel] [PATCH] ffmpeg: redesign video resampling in case of mid-stream video size/format change

[Michael Niedermayer]

On Wed, Apr 27, 2011 at 10:51:54AM +0200, Stefano Sabatini wrote:
> On date Wednesday 2011-04-27 03:12:53 +0200, Michael Niedermayer encoded:
> > On Wed, Apr 27, 2011 at 02:34:55AM +0200, Stefano Sabatini wrote:
[...]
> > > The proper fix consists in dynamic mid-stream reconfiguration, which
> > > should fix the problem also for ffplay (which now crashes/misbehaves
> > > in that case). The nice thing with the video resampling context is
> > > that it can be applied to ffplay as well, and fixes the problem at the
> > > application level while a framework solution is developed (and fixes
> > > some of the issues with the non-libavfilter path).
> > 
> 
> > what is your oppinion of moving the format/size "equalization" into
> > a seperate filter? (that could be placed after vsrc_buffer like any
> > other filter, and would
> > pass frames through unchanged when they match the output)
> 
> This would be acceptable (and could be applied also to "fix" the movie
> souuce and the ffplay input).

great


[...]
> > > > I dont understand how your solution that stores the resampling with
> > > > input streams can work without the av_vsrc_buffer_add_frame2()
> > > > when there are more output streams than input streams.
> > > > The first output might want 100x100 the second 400x400, theres only
> > > > one context so it can only scale to one.
> > > 
> > > Rescaling for the output streams is done in the libavfilter chain (a
> > > scale filter is added to the end of the filterchain, one for each
> > > output video stream), the rescale/reformat context is used only to
> > > normalize the input video.
> > 
> > This means scaling videos twice if i understand it correctly
> 
> Not different from the current solution.

The current should not scale twice

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

Many that live deserve death. And some that die deserve life. Can you give
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even the very wise cannot see all ends. -- Gandalf
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