optimization

Originally committed as revision 992 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 4 insertions, 1 deletions

diff --git a/libavcodec/mpeg12.c b/libavcodec/mpeg12.c
index 97169fa4da..18afa7630f 100644
--- a/libavcodec/mpeg12.c
+++ b/libavcodec/mpeg12.c
@@ -1604,7 +1604,10 @@ static int mpeg_decode_slice(AVCodecContext *avctx,
                 h = s->height - y;
                 if (h > 16)
                     h = 16;
-                offset = y * s->linesize;
+                if(s->pict_type==B_TYPE)
+                    offset = 0;
+                else
+                    offset = y * s->linesize;
                 if(s->pict_type==B_TYPE || (!s->has_b_frames)){
                     src_ptr[0] = s->current_picture[0] + offset;
                     src_ptr[1] = s->current_picture[1] + (offset >> 2);