[MPlayer-dev-eng] [PATCH] AltiVec IMDCT for liba52 & AltiVec detection code (for real this time...)
Romain Dolbeau
dolbeau at irisa.fr
Thu Jan 9 18:01:29 CET 2003
Sorry for the message w/o the attachement, my
memory missed a refresh cycle somehow.
#####
Hello all,
The attached patch includes
1) An AltiVec-enhanced IMDCT for liba52 (liba52/imdct.c)
It's nearly bit-perfect, I have a couple of lsb
changed in a 128 frames sample. I can't hear the
differences :-).
(My bet is the difference in rounding inside the
fused multiply-add).
2) AltiVec detection code ("borrowed" from FFmpeg) &
enough code to enable the AltiVec IMDCT in liba52
3) The libavcodec AltiVec-enable patch sent previously
(configure one-liner)
BTW, is there a 'good' way to check for codec speed ?
I tried -benchmark but it's not nearly precise enough
to estimate the AltiVec speed-up (or even if it's > 1 :-)
Also, maybe I should send the patch to the liba52
project, but it seems there's no CPU-specific
optimizations in their source tree.
--
Romain Dolbeau
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