[FFmpeg-devel] [PATCH/RFC] Add some dsputil functions useful for AAC decoder

[Michael Niedermayer]

On Fri, Sep 18, 2009 at 11:11:55PM +0100, Mans Rullgard wrote:
> This patch adds a few dsputil functions that can be used in the AAC
> decoder.
> 
> With trivial NEON versions of these functions, the AAC decoder gets
> ~1.6x faster on Cortex-A8, and better NEON code will push that even
> further.
> 
> I will readily admit that some of the names in this patch are rubbish,
> so please suggest something better.  Other enhancements are obviously
> welcome too.
[...]

> diff --git a/libavcodec/dsputil.h b/libavcodec/dsputil.h
> index d9d7d16..61252f5 100644
> --- a/libavcodec/dsputil.h
> +++ b/libavcodec/dsputil.h
> @@ -397,6 +397,14 @@ typedef struct DSPContext {
>      /* assume len is a multiple of 8, and arrays are 16-byte aligned */
>      void (*int32_to_float_fmul_scalar)(float *dst, const int *src, float mul, int len);
>      void (*vector_clipf)(float *dst /* align 16 */, const float *src /* align 16 */, float min, float max, int len /* align 16 */);
> +    void (*vector_fmul_scalar)(float *dst, const float *src, float mul,
> +                               int len);
> +    void (*vector_fmul_scalar_vp[2])(float *dst, const float *src,
> +                                     const float **vp, float mul, int len);
> +    void (*vp_fmul_scalar[2])(float *dst, const float **vp,
> +                              float mul, int len);
> +    float (*scalarproduct_float)(const float *v1, const float *v2, int len);
> +    void (*butterflies_float)(float *v1, float *v2, int len);

missing doxy
also, without seeing how these all are used i do have the feeling that
they maybe are too small primitives and that bigger chunks of aac code
should be optimized to increase flexibility and reduce call overhead ...
and i would suggest to only optimize code when it matters speedwise and
not when the code just makes up <1% of the cpu time, alex reply made
me think that this may apply to some code in there ...

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Dictatorship naturally arises out of democracy, and the most aggravated
form of tyranny and slavery out of the most extreme liberty. -- Plato
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