[FFmpeg-cvslog] drawtext: fix and optimize yuv blend.

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michaelni at gmx.at> | Tue Feb 22 00:54:48 2011 +0100| [a5b81c317e7db9015ebbf838bc065e4d183bf61a] | committer: Anton Khirnov

drawtext: fix and optimize yuv blend.

Signed-off-by: Michael Niedermayer <michaelni at gmx.at>
Signed-off-by: Anton Khirnov <anton at khirnov.net>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=a5b81c317e7db9015ebbf838bc065e4d183bf61a
---

 libavfilter/vf_drawtext.c |   10 ++++++----
 1 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/libavfilter/vf_drawtext.c b/libavfilter/vf_drawtext.c
index ad9cadc..4a0d9dc 100644
--- a/libavfilter/vf_drawtext.c
+++ b/libavfilter/vf_drawtext.c
@@ -385,12 +385,14 @@ static int config_input(AVFilterLink *inlink)
 
 #define SET_PIXEL_YUV(picref, yuva_color, val, x, y, hsub, vsub) {           \
     luma_pos    = ((x)          ) + ((y)          ) * picref->linesize[0]; \
-    chroma_pos1 = ((x) >> (hsub)) + ((y) >> (vsub)) * picref->linesize[1]; \
-    chroma_pos2 = ((x) >> (hsub)) + ((y) >> (vsub)) * picref->linesize[2]; \
     alpha = yuva_color[3] * (val) * 129;                               \
     picref->data[0][luma_pos]    = (alpha * yuva_color[0] + (255*255*129 - alpha) * picref->data[0][luma_pos]   ) >> 23; \
-    picref->data[1][chroma_pos1] = (alpha * yuva_color[1] + (255*255*129 - alpha) * picref->data[1][chroma_pos1]) >> 23; \
-    picref->data[2][chroma_pos2] = (alpha * yuva_color[2] + (255*255*129 - alpha) * picref->data[2][chroma_pos2]) >> 23; \
+    if (((x) & ((1<<(hsub)) - 1)) == 0 && ((y) & ((1<<(vsub)) - 1)) == 0) {\
+        chroma_pos1 = ((x) >> (hsub)) + ((y) >> (vsub)) * picref->linesize[1]; \
+        chroma_pos2 = ((x) >> (hsub)) + ((y) >> (vsub)) * picref->linesize[2]; \
+        picref->data[1][chroma_pos1] = (alpha * yuva_color[1] + (255*255*129 - alpha) * picref->data[1][chroma_pos1]) >> 23; \
+        picref->data[2][chroma_pos2] = (alpha * yuva_color[2] + (255*255*129 - alpha) * picref->data[2][chroma_pos2]) >> 23; \
+    }\
 }
 
 static inline int draw_glyph_yuv(AVFilterBufferRef *picref, FT_Bitmap *bitmap, unsigned int x,