From c0402e1e30c2318359af1bce1d652f4616b21566 Mon Sep 17 00:00:00 2001
From: Jerome Borsboom <jerome.borsboom@carpalis.nl>
Date: Fri, 18 May 2018 17:06:23 +0200
Subject: [PATCH] avcodec/vc1: fix mquant calculation for interlace field
pictures
For interlace field pictures s->mb_height indicates the height of the full
picture in MBs, i.e. the two fields combined. A single field is half this
size. When calculating mquant for interlace field pictures, the bottom edge
is the last MB row of the field.
Signed-off-by: Jerome Borsboom <jerome.borsboom@carpalis.nl>
---
libavcodec/vc1_block.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/libavcodec/vc1_block.c b/libavcodec/vc1_block.c
index 2d76da293b3..21ab1081697 100644
--- a/libavcodec/vc1_block.c
+++ b/libavcodec/vc1_block.c
@@ -181,7 +181,8 @@ static void vc1_put_signed_blocks_clamped(VC1Context *v)
mquant = -v->altpq; \
if ((edges&4) && s->mb_x == (s->mb_width - 1)) \
mquant = -v->altpq; \
- if ((edges&8) && s->mb_y == (s->mb_height - 1)) \
+ if ((edges&8) && \
+ s->mb_y == ((s->mb_height >> v->field_mode) - 1)) \
mquant = -v->altpq; \
if (!mquant || mquant > 31) { \
av_log(v->s.avctx, AV_LOG_ERROR, \
--
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