[FFmpeg-devel] [PATCH]Add refdist_flag to VC1Context

[Reimar Döffinger]

On Wed, Jan 07, 2009 at 10:02:24AM -0800, Stephen Warren wrote:
> Reimar D?ffinger wrote:
> > On Wed, Jan 07, 2009 at 04:00:26PM +0000, Carl Eugen Hoyos wrote:
> > > Reimar D?ffinger <Reimar.Doeffinger <at> stud.uni-karlsruhe.de> writes:
> > > > On Tue, Jan 06, 2009 at 02:02:12PM +0100, Carl Eugen Hoyos wrote:
> > > > > To add VDPAU support for VC1, refdist has to be exported to
> > > > > VC1Context.
> > > >
> > > > What is the meaning of that flag?
> > >
> > > /usr/include/vdpau/vdpau.h says:
> > > Copy of the VC-1 bitstream field. See VC-1 6.2.4.
> > >
> > > It turned out that it makes no difference for the samples I tried.
> > > I still think it is good to export the flag if possible.
> > 
> > I doubt the flag is relevant, but going by some early draft it should
> > be the same as
> > pict_type == FF_I_TYPE || pict_type == FF_B_TYPE
> > in which case there would be no point in exporting it.
> > To test, you should at least use one of the interlaced VC-1 samples,
> > otherwise I think that code won't even be reached...
> 
> I doubt it's equivalent to that pict_type formula, or the field would
> not be present in the stream; it could simply be derived.
> 
> This flag indicates whether the refdist syntax element is present in
> The stream or not, and hence is required for a VLD-level decoder
> (such as VDPAU) to parse the stream data correctly.

Probably my fault for using a draft, in that the condition is exactly
that pict_type condition.
Someone probably would have to check the proper specification (or
reference decoder).
I don't object to the change, but it would be nice if it came with a
comment why our software decoder does not need it (I suspect either a
bug or more likely missing support for interlaced formats).

Greetings,
Reimar D?ffinger