[FFmpeg-devel] [PATCH] lavfi/avf_showspectrum: replace pow(x, 0.25) by sqrt(sqrt(x))

[Ganesh Ajjanagadde]

On Mon, Jan 4, 2016 at 6:38 PM, Ganesh Ajjanagadde
<gajjanagadde at gmail.com> wrote:
> This is faster; precision assured as result is a float.
>
> Signed-off-by: Ganesh Ajjanagadde <gajjanagadde at gmail.com>
> ---
>  libavfilter/avf_showspectrum.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/libavfilter/avf_showspectrum.c b/libavfilter/avf_showspectrum.c
> index accd8c7..cff98ff 100644
> --- a/libavfilter/avf_showspectrum.c
> +++ b/libavfilter/avf_showspectrum.c
> @@ -578,7 +578,7 @@ static int plot_spectrum_column(AVFilterLink *inlink, AVFrame *insamples)
>                  a = cbrt(a);
>                  break;
>              case FOURTHRT:
> -                a = pow(a, 0.25);
> +                a = sqrt(sqrt(a));
>                  break;
>              case FIFTHRT:
>                  a = pow(a, 0.20);
> --
> 2.6.4
>

ping