On 10/9/2012 7:37 PM, Ronald S. Bultje wrote:
Hi,
On Tue, Oct 9, 2012 at 1:38 PM, Mashiat Sarker Shakkhar
<mashiat.sar...@gmail.com> wrote:
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 problem only affects chroma Y motion vector.
---
libavcodec/vc1dec.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/libavcodec/vc1dec.c b/libavcodec/vc1dec.c
index 42eb4a5..2683c86 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) {
I'm slightly curious why this is only the case for the vertical
dimension, but not the horizontal. Is that intentional, or an
oversight?
This thread contains my earlier discussion on a rejected patch which
tried to fix the same bug:
http://patches.libav.org/patch/26240/
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