[FFmpeg-cvslog] avcodec/vc1dec: fix mby_start for interlaced content

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michaelni at gmx.at> | Sat Dec 14 17:11:21 2013 +0100| [c9f72e4b81ae44d1a61459e85a3e1216a239a8ee] | committer: Michael Niedermayer

avcodec/vc1dec: fix mby_start for interlaced content

Fixes first frame of Ticket2531

Signed-off-by: Michael Niedermayer <michaelni at gmx.at>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=c9f72e4b81ae44d1a61459e85a3e1216a239a8ee
---

 libavcodec/vc1dec.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libavcodec/vc1dec.c b/libavcodec/vc1dec.c
index b2ca5de..9ed565c 100644
--- a/libavcodec/vc1dec.c
+++ b/libavcodec/vc1dec.c
@@ -5858,7 +5858,7 @@ static int vc1_decode_frame(AVCodecContext *avctx, void *data,
                                   buf_size3 << 3);
                     /* assuming that the field marker is at the exact middle,
                        hope it's correct */
-                    slices[n_slices].mby_start = s->mb_height >> 1;
+                    slices[n_slices].mby_start = s->mb_height + 1 >> 1;
                     n_slices1 = n_slices - 1; // index of the last slice of the first field
                     n_slices++;
                     break;
@@ -5909,7 +5909,7 @@ static int vc1_decode_frame(AVCodecContext *avctx, void *data,
                 buf_size3 = vc1_unescape_buffer(divider + 4, buf + buf_size - divider - 4, slices[n_slices].buf);
                 init_get_bits(&slices[n_slices].gb, slices[n_slices].buf,
                               buf_size3 << 3);
-                slices[n_slices].mby_start = s->mb_height >> 1;
+                slices[n_slices].mby_start = s->mb_height + 1 >> 1;
                 n_slices1 = n_slices - 1;
                 n_slices++;
             }