[Ffmpeg-devel] libswscale and vertically flipped images

Michael Niedermayer michaelni
Thu Jan 11 21:32:54 CET 2007


On Thu, Jan 11, 2007 at 04:45:28PM +0100, Luca Abeni wrote:
> Hi Michael,
> On Tue, 2007-01-09 at 21:18 +0100, Michael Niedermayer wrote:
> [...]
> > > My understanding is that the only difference between sws_scale() and
> > > sws_scale_ordered() should be that the second one does not reorder the U
> > > and V planes 
> > 
> > yes
> > 
> > 
> > > (but since mplayer always provides ordered planes to
> > > libswscale, it should be useless to have both sws_scale() and
> > > sws_scale_ordered()).
> > 
> > yes, seems so ...
> > 
> > 
> > > So, I would be tempted to say that introducing
> > > support for negative line sizes in sws_scale_ordered() only was an
> > > error... And that such code should be copied in sws_scale() too.
> > 
> > yes
> > 
> > and one of them, as they are identical then could be marked deprecated
> Ok. I while doing this, I initially wanted to do some cleanup of this
> code, but then I decided to go for the simplest patch. If cleanups are
> needed, we can do them later.
> The first attached patch adds support for negative linesizes in
> sws_scale() (using the sws_scale_ordered() code), and the second one
> deprecates sws_scale_ordered(). In the next days, I'll provide a patch
> removing all the sws_scale_ordered() calls from mplayer.
> BTW: I had an avi file that showed the problem by causing a negative
> linesize, but I cannot find it anymore (or maybe some code changed in
> the meanwhile)... The only way I can trigger the "vertical flip" problem
> right now is by using .mtv files, after removing the last commit in
> libavformat/mtv.c.
> So, I do not know if I should apply the patches now, or I should wait
> until someone provides a file that can reproduce the problem.

i dont know if the patches fix the -linesize problem (actually my guess
is no) but either way first fixes a bug second marks duplicate code as
deprecated so they should be applied

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Dictatorship naturally arises out of democracy, and the most aggravated
form of tyranny and slavery out of the most extreme liberty. -- Plato
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