Fix blend_subrect for subrects positioned on odd rows.

Patch by Björn Axelsson gecko A acc D umu D se

Originally committed as revision 17013 to svn://svn.ffmpeg.org/ffmpeg/trunk

ffplay.c

@@ -495,6 +495,8 @@ static void blend_subrect(AVPicture *dst, const AVSubtitleRect *rect, int imgw,
             lum[0] = ALPHA_BLEND(a, lum[0], y, 0);
             cb[0] = ALPHA_BLEND(a >> 2, cb[0], u, 0);
             cr[0] = ALPHA_BLEND(a >> 2, cr[0], v, 0);
+            p++;
+            lum++;
         }
         p += wrap3 + (wrap3 - dstw * BPP);
         lum += wrap + (wrap - dstw - dstx);