[FFmpeg-devel] [PATCH] Fix unaligned fill_rectangle in rv34.c

[Kostya]

On Fri, Aug 21, 2009 at 11:57:08AM +0200, Michael Niedermayer wrote:
> On Thu, Aug 20, 2009 at 10:33:19AM +0300, Kostya wrote:
> > On Thu, Aug 20, 2009 at 09:14:54AM +0200, Reimar D?ffinger wrote:
> > > Hello,
> > > rv34.c uses fill_rectangle with only 4 bytes alignment, which causes
> > > crashes on 64 bit architectures without unaligned read support like
> > > Sparc/Solaris.
> > > This patch hacks rectangle.h to support this kind of use - this
> > > seemed the simplest, even though rather hackish, way to me.
> > 
> > May I add that it happens when zeroing motion vectors for some
> > macroblock, i.e. where there will be non-64bit align for sure.
> > 
> > Probably better solution would be to disable this code automatically for
> > such archs. I don't remember an outcome of my discussion with Mans
> > about that though.
> 
> I dont know about your discussion with mans, but if i remember correctly
> and dont mix this up with some other issue, then at least my conclusion
> was that your code is buggy and fails to align the code correctly.
> IIRC something about using a random incorrect *_stride but i might
> missremember

That was another alignment issue which is fixed now.
Now it happens with zeroing motion_val[] which has guaranteed alignment 32
but even macroblocks will have motion_val[] with that alignment while
some CPUs (Sparc) require aligment 64 to fill it as int64.
 
> [...]
> -- 
> Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB