[FFmpeg-devel] [HACK] 50% faster H.264 decoding

[Michael Niedermayer]

On Tue, Aug 17, 2010 at 11:01:03AM -0400, Ronald S. Bultje wrote:
> Hi,
> 
> On Mon, Aug 16, 2010 at 6:40 PM, Jason Garrett-Glaser
> <darkshikari at gmail.com> wrote:
> > On Mon, Aug 16, 2010 at 3:35 PM, Ronald S. Bultje <rsbultje at gmail.com> wrote:
> >> Hi,
> >>
> >> On Wed, Aug 11, 2010 at 5:32 PM, Jason Garrett-Glaser
> >> <darkshikari at gmail.com> wrote:
> >>> 13. Use MPEG-2 MC for chroma MC, since we know that MVs are
> >>> fullpel-only. ?Simplify edge emulation stuff accordingly too.
> >>
> >> Does h264 chroma subpel actually use a memcpy shortcut if it's
> >> fullpel? I don't remember exactly, but I don't think it has such a
> >> shortcut for chroma, only for luma.
> >
> > It doesn't. ?It should at least have a shortcut for the 0,0 motion
> > vector because its very high probability (relative to other fullpel
> > motion vectors that result in no chroma interpolation). ?For other
> > cases, it might or might not be worthwhile to add a branch in the asm
> > to the 1D-only case.
> 
> Attached sets up framework for that. The [0] functions can be copied
> straight from VP8 (they are pixel_copy functions, with very fast
> aligned implementations for all relevant archs) and others, and should
> make VC-1, RV3/4, h264, H264/MPEG etc. significantly faster for the
> MVxy==0 case. The [1]/[2] functions are probably going to be faster as
> well but that would need some testing to see how big the effect is.
> [3] is the function as-is now, which should obviously stay the way it
> is.
> 
> Michael, OK to apply this? It's mostly just changing all kind of files

if its not slower ...

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Democracy is the form of government in which you can choose your dictator
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