[FFmpeg-cvslog] vc1dec: Invoke edge emulation regardless of MV precision for 1-MV chroma

[Mashiat Sarker Shakkhar]

ffmpeg | branch: master | Mashiat Sarker Shakkhar <mashiat.sarker at gmail.com> | Tue Oct  9 19:38:16 2012 +0000| [7cc3c4e1d4179aeabcd891090e31ee5e5bfd9692] | committer: Derek Buitenhuis

vc1dec: Invoke edge emulation regardless of MV precision for 1-MV chroma

This is required due to the way VC-1 handles chroma pull-back which may end
up causing negative chroma MV for zero luma MV. Edge emulation needs to be
invoked in such cases.

This only affects vertical component of chroma motion vector.

Signed-off-by: Derek Buitenhuis <derek.buitenhuis at gmail.com>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=7cc3c4e1d4179aeabcd891090e31ee5e5bfd9692
---

 libavcodec/vc1dec.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libavcodec/vc1dec.c b/libavcodec/vc1dec.c
index 4127691..491e200 100644
--- a/libavcodec/vc1dec.c
+++ b/libavcodec/vc1dec.c
@@ -430,7 +430,7 @@ static void vc1_mc_1mv(VC1Context *v, int dir)
     if (v->rangeredfrm || (v->mv_mode == MV_PMODE_INTENSITY_COMP)
         || s->h_edge_pos < 22 || v_edge_pos < 22
         || (unsigned)(src_x - s->mspel) > s->h_edge_pos - (mx&3) - 16 - s->mspel * 3
-        || (unsigned)(src_y - s->mspel) > v_edge_pos    - (my&3) - 16 - s->mspel * 3) {
+        || (unsigned)(src_y - 1)        > v_edge_pos    - (my&3) - 16 - 3) {
         uint8_t *uvbuf = s->edge_emu_buffer + 19 * s->linesize;
 
         srcY -= s->mspel * (1 + s->linesize);