[Ffmpeg-devel] [REQUEST] MMX/MMX2 and SSE optimizations for H.264 decoding

Marcus Hunger marcus.hunger
Thu Sep 15 14:29:48 CEST 2005


Am 15 Sep 2005 um 14:06 hat Martin Boehme geschrieben:

> Reimar D??ffinger wrote:
> > On Thu, Sep 15, 2005 at 01:02:22PM +0200, Martin Boehme wrote:
> >>information (believe me, the guys who would be candidates for this 
> >>_know_ where to get the Intel Reference Manual...).
> > 
> > I guess that rules me out, I only got the AMD manuals :-P
> 
> I assume you'd know where to get the Intel manual if you needed it, 
> though... ;-)
> 
> >>at libavcodec/i386/h264dsp_mmx.c). Now, I don't know if that covers all 
> >>of the areas that could benefit from MMX (Michael?), but the point is: 
> >>H.264 _is_ a performance-hungry codec, even for decoding, and it may 
> >>just be too much for an Xbox...
> > 
> > I know you can't trust it too much, but last time I checked oprofile
> > indicated a lot of time is spent in some more general "parsing" and
> > comparisons that can't be easily converted to e.g. MMX...
> > So yes, if somebody knows a code part that could still really benefit from
> > e.g. MMX please say so, because I didn't see any.
> 
> And if FFmpeg is faster than Nero, that would also seem to indicate that 
> there probably isn't too much "low-hanging fruit"...
> 
I visited the Frauenhofer I. booth at the ibc and they showed off with their h264 decoder 
(running on a pocket pc)  telling me it would be much faster than ffmpeg's. So I guess 
there is room for optimization.

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