[FFmpeg-devel] [PATCH] Port AAC decoder to use ff_imdct_half and vector_fmul_window

Guillaume POIRIER poirierg
Fri Aug 22 16:22:10 CEST 2008


On Fri, Aug 22, 2008 at 4:18 PM, Robert Swain <robert.swain at gmail.com> wrote:
> 2008/8/22 Robert Swain <robert.swain at gmail.com>:


> Just for fun, for the same file, I benchmarked FAAD. Taking the best
> user time and comparing to the ffaac decoder with the posted patches,
> I infer that ffaac is ~135% faster than FAAD. :) Benchmark results
> below:
> real    0m15.781s
> user    0m15.050s
> sys     0m0.543s
> real    0m15.578s
> user    0m14.551s
> sys     0m0.558s
> real    0m15.919s
> user    0m15.046s
> sys     0m0.578s
> real    0m15.966s
> user    0m15.189s
> sys     0m0.558s
> real    0m15.888s
> user    0m15.019s
> sys     0m0.578s

I'm not surprised. The FFT used in FAAC is very inefficient and slow.
BTW, does your AAC decoder use Loren's ASM-optimized split-radix FFT?

One should not give up hope on imbeciles. With a little training, you
can make them into soldiers.
 -- Pierre Desproges

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