[FFmpeg-devel] [PATCH] VP8: faster filter_level clip

[Måns Rullgård]

Jason Garrett-Glaser <jason at x264.com> writes:

> ---
>  libavcodec/vp8.c |    5 ++++-
>  1 files changed, 4 insertions(+), 1 deletions(-)
>
> diff --git a/libavcodec/vp8.c b/libavcodec/vp8.c
> index bcf6237..1db57e4 100644
> --- a/libavcodec/vp8.c
> +++ b/libavcodec/vp8.c
> @@ -1480,7 +1480,10 @@ static av_always_inline void filter_level_for_mb(VP8Context *s, VP8Macroblock *m
>          filter_level += s->lf_delta.ref[mb->ref_frame];
>          filter_level += s->lf_delta.mode[mb->mode];
>      }
> -    filter_level = av_clip(filter_level, 0, 63);
> +
> +/* Like av_clip for inputs 0 and max, where max is equal to (2^n-1) */
> +#define POW2CLIP(x,max) (((x) & ~max) ? (-(x))>>31 & max : (x));
> +    filter_level = POW2CLIP(filter_level, 63);

ARM has an instruction for that.  We should make sure it gets used.

-- 
M?ns Rullg?rd
mans at mansr.com