[FFmpeg-devel] Fix MMX dct_quantize for non zigzag_direct scans

[Michael Niedermayer]

On Mon, May 19, 2008 at 05:44:40PM +0100, Ramiro Polla wrote:
> Michael Niedermayer wrote:
> > On Fri, May 16, 2008 at 12:55:03AM +0100, Ramiro Polla wrote:
> >> Hi,
> >>
> >> Michael Niedermayer wrote:
> >>> On Wed, May 14, 2008 at 11:25:43PM +0100, Ramiro Polla wrote:
> > [...]
> >>>> Benchmarking with START/STOP_TIMER isn't very good since the runs can vary 
> >>>> on the time they take depending on last_non_zero. Also the patch changes 
> >>>> not only the MMX code but removes the hack in mpegvideo_enc.c.
> >>> *_TIMER around the macroblock encode function seems an option
> >>> also the automatic threshold calculation could be replaced by a constant
> >>> to avoid excessive skips.
> >> I added *_TIMERs in first and last line of encode_mb_internal. These are 
> >> the results:
> >>
> >> around 1048576 runs
> >> ref          new
> >> time   skips time   skips
> >> 42612  3033  44422  2889
> >> 42551  2981  43440  2712
> >> 42553  2846  43711  2991
> >> 41825  2895  44401  3036
> >> 41812  2925  43691  2878
> >> 41792  2858  43137  2873
> >> 42458  2973  43482  2945
> >> 42388  3078  43553  2766
> >> 42366  2888  43450  2987
> >> 42721  3003  43163  2996
> >> 42210  2964  43956  2954
> >> 42299        43674        avg
> >> 341.8448     433.0284     stdev
> > 
> > the skip numbers are too high
> > 
> > try:
> > -if(tcount<2 || tend - tstart < FFMAX(32*tsum/tcount, 200000)){\
> > +if(tcount<2 || tend - tstart < FFMAX(32*tsum/tcount, 5000000)){\
> > or higher
> 
> ref     new
> 43427   45236
> 42913   44817
> 43902   44740
> 43719   44135
> 42767   44276
> 44417   44702
> 45242   45931
> 44633   44899
> 42801   45561
> 44188   44503
> 43265   44565
> 43127   45532
> 43238   44569
> 43588   44631
> 43242   44868
> 44073   45426
> 43659   44899  average
>    706.15  502.52 stdev

looks like new is slower ...


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

Those who are too smart to engage in politics are punished by being
governed by those who are dumber. -- Plato 
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