[Mplayer-dev-eng] [PATCH] libac3 SSE support

[Nick Kurshev]

Hi, Felix Bьnemann!

On 2001-07-10 10:29:35 you wrote:

>NK> In attach SSE support for libac3.
>NK> Please test it and apply if it works, otherwise - simply forget about.
>
>Great, it works (I've tested with 2.0 and 5.1 48kHz AC3) and it gives
>speedup of approx 10-15% on PIII coppermine.
>
>Btw. grabbed pcm dump of output and it differs, but think it's due to
>different srfft algorithm I think, I think it's no prob cause it
>sounds ok (did diff of audiodump.wav of mplayer with --disable-sse and
>--enable-sse).
>
The same problem was with old mp3 stuff, IMHO. It's normal since P3 has
minor different precision for FPU and SSE units (I still don't study this question
in detail). But problem is not in algorithms since there is used same algorithm
for all types of decoders (SSE, 3DNOW).

Maybe you'll want port dct64_3dnow.s (dct64_k7.s even better) to SSE as
dct64_sse.s? At least phases 1-5? They can be simply converted from
3dnow to sse, but phases 6-10 could be interleaved with 1-5 to get better
performance. (I think that per 1 SSE opcodes need 2 FPU opcodes to load
cpu optimally).

Best regards! Nick (2001-07-11 00:27:43)


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