[FFmpeg-cvslog] lavfi/delogo: don't recompute the same difference again and again

[Jean Delvare]

ffmpeg | branch: master | Jean Delvare <khali at linux-fr.org> | Fri Jul  5 10:23:18 2013 +0200| [6fc8c4cc0ef643b8d6b87b0cf20ca8792c9b2dbe] | committer: Michael Niedermayer

lavfi/delogo: don't recompute the same difference again and again

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>
Reviewed-by; Stefano Sabatini <stefasab at gmail.com>
Signed-off-by: Michael Niedermayer <michaelni at gmx.at>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=6fc8c4cc0ef643b8d6b87b0cf20ca8792c9b2dbe
---

 libavfilter/vf_delogo.c |   24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/libavfilter/vf_delogo.c b/libavfilter/vf_delogo.c
index e882dd5..3a9bdd4 100644
--- a/libavfilter/vf_delogo.c
+++ b/libavfilter/vf_delogo.c
@@ -100,21 +100,21 @@ static void apply_delogo(uint8_t *dst, int dst_linesize,
             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;
 
             if (y >= logo_y+band && y < logo_y+logo_h-band &&