[FFmpeg-cvslog] avcodec/vc1: store zero MVs for all blocks in a MB

[Jerome Borsboom]

ffmpeg | branch: master | Jerome Borsboom <jerome.borsboom at carpalis.nl> | Mon May 28 23:50:28 2018 +0200| [8a4dbd3e9fd13a0941bbb63d249ed92c2037fd4c] | committer: Carl Eugen Hoyos

avcodec/vc1: store zero MVs for all blocks in a MB

Direct prediction for interlace frame B pictures references the mv in the
second block in an MB in the backward reference frame for the twomv case.
When the backward reference frame is an I frame, this value may be unset.

Signed-off-by: Jerome Borsboom <jerome.borsboom at carpalis.nl>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=8a4dbd3e9fd13a0941bbb63d249ed92c2037fd4c
---

 libavcodec/vc1_block.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/libavcodec/vc1_block.c b/libavcodec/vc1_block.c
index 21ab108169..0160095c6c 100644
--- a/libavcodec/vc1_block.c
+++ b/libavcodec/vc1_block.c
@@ -2678,8 +2678,10 @@ static void vc1_decode_i_blocks_adv(VC1Context *v)
             s->bdsp.clear_blocks(block[0]);
             mb_pos = s->mb_x + s->mb_y * s->mb_stride;
             s->current_picture.mb_type[mb_pos + v->mb_off]                         = MB_TYPE_INTRA;
-            s->current_picture.motion_val[1][s->block_index[0] + v->blocks_off][0] = 0;
-            s->current_picture.motion_val[1][s->block_index[0] + v->blocks_off][1] = 0;
+            for (int i = 0; i < 4; i++) {
+                s->current_picture.motion_val[1][s->block_index[i] + v->blocks_off][0] = 0;
+                s->current_picture.motion_val[1][s->block_index[i] + v->blocks_off][1] = 0;
+            }
 
             // do actual MB decoding and displaying
             if (v->fieldtx_is_raw)