[FFmpeg-cvslog] Check for missing reference in vp5/6 decoder.

[Laurent Aimar]

ffmpeg | branch: release/0.8 | Laurent Aimar <fenrir at videolan.org> | Wed Sep 21 20:46:30 2011 +0200| [a5a02ea3f2bb4e89d9ee0e381c938bd83e5c369d] | committer: Michael Niedermayer

Check for missing reference in vp5/6 decoder.

Signed-off-by: Michael Niedermayer <michaelni at gmx.at>
(cherry picked from commit 6a0e78929aa7d6b2c6b598c1589fb0e48fccb132)

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=a5a02ea3f2bb4e89d9ee0e381c938bd83e5c369d
---

 libavcodec/vp56.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/libavcodec/vp56.c b/libavcodec/vp56.c
index ad451c2..cf89176 100644
--- a/libavcodec/vp56.c
+++ b/libavcodec/vp56.c
@@ -399,6 +399,8 @@ static void vp56_decode_mb(VP56Context *s, int row, int col, int is_alpha)
 
     frame_current = s->framep[VP56_FRAME_CURRENT];
     frame_ref = s->framep[ref_frame];
+    if (mb_type != VP56_MB_INTRA && !frame_ref->data[0])
+        return;
 
     ab = 6*is_alpha;
     b_max = 6 - 2*is_alpha;