[FFmpeg-devel] [PATCH] H.264: x264 SSE2 iDCT functions

[Michael Niedermayer]

On Fri, Jan 02, 2009 at 07:44:54PM -0500, Jason Garrett-Glaser wrote:
> On Fri, Jan 2, 2009 at 6:12 PM, Michael Niedermayer <michaelni at gmx.at> wrote:
> > On Fri, Jan 02, 2009 at 04:36:11PM -0500, Jason Garrett-Glaser wrote:
> >> On Fri, Jan 2, 2009 at 4:14 PM, Guillaume POIRIER <poirierg at gmail.com> wrote:
> >> > Hello,
> >> >
> >> > On Fri, Jan 2, 2009 at 9:37 PM, Jason Garrett-Glaser
> >> > <darkshikari at gmail.com> wrote:
> >> >
> >> >> Patch attached.
> >> >
> >> >> +#if defined(CONFIG_GPL) && defined(HAVE_YASM)
> >> >> +static void ff_h264_idct_dc_add8_mmx2(uint8_t *dst, int16_t *block, int stride)
> >> >> +{
> >> >>
> >> >
> >> > This is just to avoid having unreferenced code, right? I assume you're
> >> > not doing to license ff_h264_idct_dc_add8_mmx2 under GPL...
> >>
> >> Yes, of course.  I can't license it under GPL, it's basically copied
> >> from the original idct_dc.
> >>
> >> Also, Michael, why isn't idct_add8 (the chroma 8-4x4idct function)
> >> used at all?  Did you forget to insert it when you added
> >> add16/add16_intra into h264.c?
> >
> > i benchmarked it, and it was slower, thats why its not in svn ...
> > I dont know why it was slower ...
> 
> Is it slower if you use the SSE2 iDCT functions?

well, it was slower with the very same mmx* idct on both sides of the
benchmark.
I would like to understand why before it is enabled, even if the SSE2
idct with the new code might beat the old with mmx. The old still would
be faster for pre SSE2 cpus ...

but then, the changes needed in the code are rather small so it should
no be hard to enable it by #ifdef, this also would make testing easier
for our users ...

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Why not whip the teacher when the pupil misbehaves? -- Diogenes of Sinope
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