[FFmpeg-devel] [PATCH] Faster CABAC H.264 residual decoding

[Guillaume POIRIER]

Hello,

On Sun, May 4, 2008 at 3:18 AM, Alexander Strange <astrange at ithinksw.com> wrote:
>  On May 3, 2008, at 5:21 PM, Michael Niedermayer wrote:
> >
> > I prefer uint8_t arrays, the speed loss they could cause is purely
> > hypothetical while the int arrays will need 100 bytes more precious L1
> cache.
> >
> > Besides this, the patch is ok if its faster on average.
> >
> > [...]
> >
>
>  Here it is with uint8_t.
>
>  On Core 2:
>  old: avg 9.113 max 9.135 min 9.09
>  new: avg 9.068 max 9.077 min 9.061
>
>  It should be faster than with int on any RISC.

How did you measure the speed? Did you measure overall decoding speed
with "time", or did you used START_TIMER/STOP_TIMER around the
relevant function?

I can test on PPC970 to have an idea of how this new code behaves on a
RISC machine.


> I'll apply it tomorrow
> unless someone thinks it's still worse on Athlon.

Well, I guess it's better to measure speed on Athlon rather than
making a wild guess ;-)

Guillaume

-- 
I don't measure a man's success by how high he climbs but how high he
bounces when he hits bottom.
 -- George S. Patton