[FFmpeg-devel] [PATCH 1/4] lavfi/delogo: don't recompute the same difference again and again

[Stefano Sabatini]

On date Friday 2013-07-05 10:23:18 +0200, Jean Delvare encoded:
> The top left hand corner pixel coordinates are already stored in
> logo_x1 and logo_y1 so don't recompute each of them 6 times for every
> iteration.
> 
> This is a simple code optimization, result is obviously the same. The
> performance gain is small (about 2% in my tests) but still good to
> have, and the new code is clearer.
> 
> Signed-off-by: Jean Delvare <khali at linux-fr.org>
> ---
>  libavfilter/vf_delogo.c |   24 ++++++++++++------------
>  1 file changed, 12 insertions(+), 12 deletions(-)
> 
> --- ffmpeg.orig/libavfilter/vf_delogo.c	2013-06-28 10:46:25.562635244 +0200
> +++ ffmpeg/libavfilter/vf_delogo.c	2013-06-28 10:46:46.316635552 +0200
> @@ -100,21 +100,21 @@ static void apply_delogo(uint8_t *dst, i
>              weightb = (uint64_t)(x-logo_x1) * (logo_x2-1-x) * (y-logo_y1)                 * sar.num;
>  
>              interp =
> -                (topleft[src_linesize*(y-logo_y  -yclipt)]   +
> -                 topleft[src_linesize*(y-logo_y-1-yclipt)]   +
> -                 topleft[src_linesize*(y-logo_y+1-yclipt)])  * weightl
> +                (topleft[src_linesize*(y-logo_y1)]    +
> +                 topleft[src_linesize*(y-logo_y1-1)]  +
> +                 topleft[src_linesize*(y-logo_y1+1)]) * weightl
>                  +
> -                (topright[src_linesize*(y-logo_y-yclipt)]    +
> -                 topright[src_linesize*(y-logo_y-1-yclipt)]  +
> -                 topright[src_linesize*(y-logo_y+1-yclipt)]) * weightr
> +                (topright[src_linesize*(y-logo_y1)]    +
> +                 topright[src_linesize*(y-logo_y1-1)]  +
> +                 topright[src_linesize*(y-logo_y1+1)]) * weightr
>                  +
> -                (topleft[x-logo_x-xclipl]    +
> -                 topleft[x-logo_x-1-xclipl]  +
> -                 topleft[x-logo_x+1-xclipl]) * weightt
> +                (topleft[x-logo_x1]    +
> +                 topleft[x-logo_x1-1]  +
> +                 topleft[x-logo_x1+1]) * weightt
>                  +
> -                (botleft[x-logo_x-xclipl]    +
> -                 botleft[x-logo_x-1-xclipl]  +
> -                 botleft[x-logo_x+1-xclipl]) * weightb;
> +                (botleft[x-logo_x1]    +
> +                 botleft[x-logo_x1-1]  +
> +                 botleft[x-logo_x1+1]) * weightb;
>              interp /= (weightl + weightr + weightt + weightb) * 3U;

LGTM, thanks.
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