[FFmpeg-devel] Another H.264 decoding image corruption issue

Paul Kendall paul
Fri Jul 25 23:42:08 CEST 2008

On Friday 25 July 2008 23:17:15 Michael Niedermayer wrote:
> On Fri, Jul 25, 2008 at 07:04:05PM +1200, Paul Kendall wrote:
> > Michael,
> > I have been reading the ITU H264 spec and going through the code at the
> > same time and I think the part that needs fixing (from the FIXME in
> > h264.c line 995) is the colocated block calculation which is from section
> > when field_pic_flag is 1. Am I on the right track with my
> > thinking? If so, I am still hunting for the section of code where the
> > calculation needs to take place. Can you help me with this, please?
> no, you will have to follow your hypothesis yourself.
Ok, I'll give it a go! It may take a bit longer to come to terms with it all!

> > Another thing that may be helpful for others reading the code is comments
> > with specification section numbers! Perhaps as I start to understand it I
> > will create a patch with comments which contains section numbers.
> cleanup patches are welcome, If section references are welcome, that iam
> not sure. There surely are places where comments refering to the spec make
> sense And there are many where they do not.
> Either way ALWAYS use section names NEVER numbers. Numbers change, the
> small number of section numbers currently in h264.c does no longer match
> the apparently intended sections. (so assuming they did in the past, the
> nums must have changed)
> Also keep in mind h264.c is not a litteral sentance by sentance
> implementation of the spec. At least not the parts that work. They are
> rather equivalent processes producing the same result for the same input as
> the process written in the spec.
> [...]
Ok, If I can figure out any of this I'll add references to section titles 
rather than numbers. If I see some cleanups that can be done i.e. so FIXME's 
I'll give them a go too.


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