[Ffmpeg-devel] Snow slicing support

Michael Niedermayer michaelni
Thu Apr 6 17:19:57 CEST 2006


On Mon, Apr 03, 2006 at 09:47:58PM +0300, Oded Shimon wrote:
> Just thought this patch might be of general interest to anyone. What I 
> find interesting about it, is that it's not the sliced output that helps 
> at all, but the rearranging of how the data is handled, of unpacking 
> coeffs seperately from decoding image. It is actually a surprisngly huge 
> difference on my cpu, almost 20% faster in some cases. This code trades 
> off code switches against data switches, and even in my high res video 
> (944x544), code switches prooved to be far more expensive...
> I don't really expect this patch to go in CVS, but I am interested in any 
> comments if anyone has any...

this needs testing with different resolutions, bitrates and cpus
(320x240 720x576 p4 athlon ...)

is this speed difference also there with other gcc versions
and most interresting is it there too at lower -O

if its consistently faster (or at least not slower) then this should be



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