[FFmpeg-devel] [PATCH] Revert: mpegvideo: Drop err_recognition AND mpegvideo: Drop flags and flags2

[Clément Bœsch]

On Fri, May 22, 2015 at 11:59:54PM +0200, Michael Niedermayer wrote:
> this increases mpeg4 and msmpeg4v3 decoding speed by about 0.3-0.5% overall
> 
> This reverts the merges of 848e86f74d3e6e87fa592ee8ba8c184cc5fd9a42 and 9c1db92ad372d4cd69e0490e691c56e4097cb193
> 
> Speed tested with decoding matrixbench_mpg4.avi and matrixbench_msmpeg4v3.avi
> Test files where generated as in
> ./ffmpeg -i matrixbench_mpeg2.mpg -vb 1000k -vcodec mpeg4 matrixbench_mpg4.avi
> 
> benchmarked with:
> time ./ffmpeg -an -i matrixbench_mpg4.avi -an -f null -
> 
> benchmarks: (each is best time of 7)
> the values fluctuate but its consistently faster when reverted
> 
> new 0m1.910s
> reverted 0m1.901s
> 
> new 1.907
> reverted 1.904
> 
> new 1.908
> reverted 1.907
> 
> new 0.461
> reverted 0.459
> 
> new 0.461
> reverted 0.459
> 
> new 0.461
> reverted 0.457
> 
> new 0.458
> reverted 0.456
> 

Can't you just make a local (to the function) copy of the variable in the
functions where it matters and gain back that negligible speedup?

[...]

-- 
Clément B.
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