[x264-devel] 8x8 and 16x16 Altivec implementation of variance

Holger Lubitz Holger.Lubitz at Informatik.Uni-Oldenburg.DE
Sat Jan 24 02:47:38 CET 2009

> The 8x8 doesn't such a big speed-up because the data is 8-bytes
> aligned, not 16-bytes aligned, so it's necessary to permute it before
> using it.

I do not know much about altivec at all, but it seems the permute may be more
expensive than a shift. Have you tried just shifting things into place?


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