[Ffmpeg-devel] patch: altivec optimizations for h264 decoder

Derk-Jan Hartman d.hartman
Mon Feb 6 17:31:28 CET 2006

I'll test it in a couple of hours on a Dual G5. (If no one did before  
I did of course).


On 6-feb-2006, at 14:07, Romain Dolbeau wrote:

> Michael Niedermayer wrote:
>> mixing declarations and statements, romain is this an issue for  
>> ppc-asm or do
>> all compilers which support ppc-asm support this too?
> They probably do. It would be intesrting to know what OS and compiler
> the author of the patches used (I don't have linux/ppc anymore).
>> romain please review and test, you are the ppc maintainer
> I am ? damn, more responsabilities :-/
> I can't test, as I don't have a sample, and if I had,
> I don't have a machine fast enough for 1080p anyway
> (the G4 isn't the fastest CPU around...)
> Patch 1 : nothing to add, except that gcc register allocator is  
> probably
> going to hate ff_h264_idct_add_altivec_mat
> Patch 2 : in PREFIX_h264_qpel4_hv_lowpass_altivec, why use
> VEC_LOAD_UNALIGNED_CHECK ? tmpbis is computed from tmp
> (comments -> assumed aligned) and tmpStride (comments ->
> multiple of 16), so it has to be aligned.
> Patch 4 : is put_pixels8_altivec really faster than the C
> version ? there's not computation whatsoever, and with the
> need to load the destination block to insert the new
> data, it may be slower to use AltiVec than regular C code.
> I'm a little bit short on time to be able to make a more
> thorough investigation, sorry
> -- 
> Romain Dolbeau
> <romain at dolbeau.org>
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