[FFmpeg-devel] [PATCH] fix H.264 crash (issue 706)

[Reimar Döffinger]

On Fri, Apr 10, 2009 at 12:11:52AM +0200, Michael Niedermayer wrote:
> On Thu, Apr 09, 2009 at 11:31:46PM +0200, Reimar D?ffinger wrote:
> > On Thu, Apr 09, 2009 at 10:42:37PM +0200, Michael Niedermayer wrote:
> > > On Thu, Apr 09, 2009 at 10:33:49PM +0200, Reimar D?ffinger wrote:
> > > > Well, but that code will only run if there is either either a DC or a MV
> > > > error (see above), whereas the problematic code will only run if there
> > > > is no MV error. So if there is only an AC error I think the code I added
> > > > above would be necessary I think...
> > > 
> > > short awnser
> > > our h264 decoder doesnt set AC_ERROR without MV_ERROR
> > 
> > But that code is not used only by H.264...
> > Also, I sure don't think at all that more undocumented, obscure, not
> > generally-correct and inconsistenly applied assumptions is really what
> > any of the MPEG-related code needs.
> > 
> > > the code is called "/* set unknown mb-type to most likely */"
> > 
> > Well, _that_ one is easily fixed.
> > Note that attached patch is completely untested right now.
> 
> the patch does look accpetable assuming it works and is tested and it
> does fix something.

It seems to work (I just don't have many test cases for error
resilience, those I tried seem unchanged), and it definitely fixes
crash with sample described in issue 706, so applied.