[FFmpeg-devel] [flamefest-start] A little something on MMX/SSE intrinsics

Luca Barbato lu_zero
Thu Feb 28 14:44:51 CET 2008

Alexander Strange wrote:
>>  >> I'd just like to add that there is already architecture in FFmpeg that
>>  >> is entirely optimized on intrinsics - AltiVect. There were few
>>  >> fundamental problems with it and I'm not sure if they have been
>>  >> successfully solved. These include things like generating code that
>>  >> picks up processor SIMD dialect at runtime.
>>  >
>>  > You just found us a new SOC qualification task
>>  > rewrite intrinsics to proper asm()
>>  >
>>  And benchmark the result ^^;
>>  lu
> I don't think anyone can get Altivec asm to work better than
> intrinsics on more than one CPU - PPC is really, really
> scheduling-sensitive, especially the G5 and Cell.

I know, that's why I put that line, I have access to a CELL (ps3) and 
g4, possibly I could ask some people to benchmark on other cpus and see 
the net result with different versions of gcc.

> I guess you can always try, though, but don't do anything to
> discourage people who know altivec from adding more. There's still a
> lot missing from H.264.

I know, no time to hack that stuff lately...

That said I think won't hurt getting some people solve this issue 
between me (liking intrisics for powerpc/spu development) and michael 
(disparaging them since his arch has them uglier and apparently slower)



Luca Barbato
Gentoo Council Member
Gentoo/linux Gentoo/PPC

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