[FFmpeg-cvslog] r17598 - trunk/libavcodec/aac.c

[Benjamin Larsson]

alexc wrote:
> Author: alexc
> Date: Thu Feb 26 02:50:00 2009
> New Revision: 17598
>
> Log:
> Use const to better allow the compiler to optimize AAC independent coupling.
>
> Modified:
>    trunk/libavcodec/aac.c
>
> Modified: trunk/libavcodec/aac.c
> ==============================================================================
> --- trunk/libavcodec/aac.c	Thu Feb 26 02:38:51 2009	(r17597)
> +++ trunk/libavcodec/aac.c	Thu Feb 26 02:50:00 2009	(r17598)
> @@ -1456,8 +1456,13 @@ static void apply_dependent_coupling(AAC
>   */
>  static void apply_independent_coupling(AACContext * ac, SingleChannelElement * target, ChannelElement * cce, int index) {
>      int i;
> +    const float gain = cce->coup.gain[index][0];
> +    const float bias = ac->add_bias;
> +    const float* src = cce->ch[0].ret;
> +    float* dest = target->ret;
> +
>      for (i = 0; i < 1024; i++)
> -        target->ret[i] += cce->coup.gain[index][0] * (cce->ch[0].ret[i] - ac->add_bias);
> +        dest[i] += gain * (src[i] - bias);
>  }
>   

Just for the record I think that not dereferencing in the loop is more 
to blame for the speedup then the const-ifying.

MvH
Benjamin Larsson