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

[Diego Biurrun]

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.

Diego