[Ffmpeg-devel] [PATCH] wma optimizations

[Benjamin Larsson]

With the new dsp vector functions in the wma decoder it shaved of about
120000 dezicycles from the windowing code loop.

Non simd before optimization:
138006 dezicycles in winmul, 4090 runs, 6 skipss dup=0 drop=0
81426 dezicycles in winspecial, 4091 runs, 5 skips
137845 dezicycles in winmul, 8172 runs, 20 skips dup=0 drop=0
81290 dezicycles in winspecial, 8177 runs, 15 skips
137565 dezicycles in winmul, 16350 runs, 34 skipsdup=0 drop=0
81051 dezicycles in winspecial, 16358 runs, 26 skips

Simd:
50668 dezicycles in winmul, 4092 runs, 4 skips/s dup=0 drop=0
42723 dezicycles in winspecial, 4091 runs, 5 skips
50486 dezicycles in winmul, 8186 runs, 6 skips
42602 dezicycles in winspecial, 8186 runs, 6 skips
50317 dezicycles in winmul, 16369 runs, 15 skips dup=0 drop=0
42464 dezicycles in winspecial, 16370 runs, 14 skips

A md5sum test on an amd64 box gave the same checksum for both versions.
But I'm not sure that would be true for all kind of simd code, but the
diffrent rounding should only lead to 1 bit differences.

Overall speedup is around 3%. (From 14.2 -> 13.8).

MvH
Benjamin Larsson

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