[Ffmpeg-devel] MPEG-1/2 decoding benchmarks

Michael Niedermayer michaelni
Mon Jul 25 21:40:13 CEST 2005


Hi

On Monday 25 July 2005 20:50, Diego Biurrun wrote:
> On Wed, Apr 27, 2005 at 01:41:50AM +0200, Diego Biurrun wrote:
> > I have repeated my MPEG-1/2 decoding benchmarks with the latest
> > revisions of mpeg12.c.
> >
> > I tested revision 1.230 - 1.233 of mpeg12.c, 1.234 had no functional
> > changes.  Log messages:
> >
> > 1.230 avoid UPDATE_CACHE() in GET_RL_VLC() if not needed
> > 1.231 optimizing non_intra ac coeff decode
> > 1.232 mpeg2_fast_decode_block_intra()
> > 1.233 avoid clearing block[] if its not used at all
> >
> > I tested on two different systems, my desktop and notebook
> >
> > desktop:
> > 500MHz AMD K6-III+
> > 512MB SD-RAM 133
> > Debian testing (up to date)
> > gcc 2.95.4 (Debian)
> >
> > notebook:
> > 1500MHz G4 with AltiVec
> > 512MB PC2700 (333MHz) DDR SDRAM
> > Debian testing (up to date)
> > gcc 3.3.5 (Debian)
> >
> >
> > RESULTS:
> >
> > K6-III: 1.231 gave a slight speedup (2.3%) in some cases, 1.232 a
> > slight performance degradation (1.7%) in some cases, no changes in
> > 1.233.
> >
> > G4: 1.231 gave a slight speedup (1.2%) in some cases, 1.232 a slight
> > improvement (1.2%) in one case, almost no changes in 1.233.
>
> Should revision 1.232 maybe be reverted?  It does not seem to have
> helped performance, at least on i386, which is the main target.  If more
> details are necessary, I can redo the benchmarks.  I distrust my PPC
> results a bit now.  Since my PowerBook is from February, the hardware
> was not yet completely supported when I did the benchmarks in April.

if its slower (almost) everywhere then it should be reverted
though it should be benchmarked again (at least with gcc 4.0 & 3.something & 
2.95) and benchmarking should use START/STOP_TIMER in avcodec_decode_video, i 
dont trust mplayers -benchmark

[...]
-- 
Michael





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