[FFmpeg-devel] [PATCH] avfilter/af_dynaudnorm: remove wasteful pow

[Paul B Mahol]

On 11/25/15, Ganesh Ajjanagadde <gajjanagadde at gmail.com> wrote:
> This removes wasteful pow(x, 2.0) that although not terribly important
> for speed, is still useless.
>
> Signed-off-by: Ganesh Ajjanagadde <gajjanagadde at gmail.com>
> ------------------------------------------------------------------------------
> Observed while auditing the codebase for wasteful pow calls.
>
> ---
>  libavfilter/af_dynaudnorm.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/libavfilter/af_dynaudnorm.c b/libavfilter/af_dynaudnorm.c
> index 62a2653..5f412f5 100644
> --- a/libavfilter/af_dynaudnorm.c
> +++ b/libavfilter/af_dynaudnorm.c
> @@ -237,13 +237,13 @@ static void
> init_gaussian_filter(DynamicAudioNormalizerContext *s)
>      // Pre-compute constants
>      const int offset = s->filter_size / 2;
>      const double c1 = 1.0 / (sigma * sqrt(2.0 * M_PI));
> -    const double c2 = 2.0 * pow(sigma, 2.0);
> +    const double c2 = 2.0 * sigma * sigma;
>
>      // Compute weights
>      for (i = 0; i < s->filter_size; i++) {
>          const int x = i - offset;
>
> -        s->weights[i] = c1 * exp(-(pow(x, 2.0) / c2));
> +        s->weights[i] = c1 * exp(-x * x / c2);
>          total_weight += s->weights[i];
>      }
>
> --
> 2.6.2
>
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel at ffmpeg.org
> http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>

probably ok