From: "Ronald S. Bultje" <rsbul...@gmail.com>
If the motion vector is at a subpixel position, we need 3 pixels below
the motion vector's wholepel position available, not 2, since the MC
filter is a sixtap filter for the hpel position, and then a bilin filter
for the qpel position.
This patch fixes highly irreproducible (0.1%) fate failures in frame 2
and 4 of h264-conformance-cama2_vtc_b (e.g. first P-frame, first field,
last line of MB x=40,y=2 and second field and last lines of MBs x=39-40,
y=3). These used pre-loopfilter instead of post-loopfilter data because
the await_progress() waited for one line too little in that field, and
the motion vector of these particular MBs happened to align exactly to a
position where that demonstrates the bug.
---
libavcodec/h264.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/libavcodec/h264.c b/libavcodec/h264.c
index e8b3e72..9541c69 100644
--- a/libavcodec/h264.c
+++ b/libavcodec/h264.c
@@ -290,10 +290,11 @@ static inline int get_lowest_part_list_y(H264Context *h,
Picture *pic, int n,
int height, int y_offset, int list)
{
int raw_my = h->mv_cache[list][scan8[n]][1];
- int filter_height = (raw_my & 3) ? 2 : 0;
+ int filter_height_up = (raw_my & 3) ? 2 : 0;
+ int filter_height_down = (raw_my & 3) ? 3 : 0;
int full_my = (raw_my >> 2) + y_offset;
- int top = full_my - filter_height;
- int bottom = full_my + filter_height + height;
+ int top = full_my - filter_height_up;
+ int bottom = full_my + filter_height_down + height;
return FFMAX(abs(top), bottom);
}
--
1.7.11.3
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