[libav-devel] [PATCH] VC1: Fix first/last row checks with slices

[Alberto Delmás]

This is a prerequisite for deterministic frame threading, as otherwise 
on B-frames the loop filter runs across edges where one side hasn't been 
decoded yet, making the output depend on the previous content of the 
buffer we get to reuse (which varies with thread count).
>From 692ccd916b954eb2837aa3721fed33156399b376 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Alberto=20Delm=C3=A1s?= <adel...@gmail.com>
Date: Thu, 25 Aug 2011 11:00:37 +0200
Subject: [PATCH] VC1: Fix first/last row checks with slices
In some places 0/mb_height were used in place of start_mb_y/end_mb_y.

Fixes SA00049, SA00058, SA10091, SA10097, SA10131, SA20021, SA30030

Improves PSNR in SA00054, SA00059, SA00060, SA10096, SA10098, SA20022,
SA30031, SA30032, SA40012, SA40013
---
 libavcodec/vc1dec.c |   14 +++++++-------
 1 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/libavcodec/vc1dec.c b/libavcodec/vc1dec.c
index 4954d4f..735d6c2 100644
--- a/libavcodec/vc1dec.c
+++ b/libavcodec/vc1dec.c
@@ -242,7 +242,7 @@ static void vc1_loop_filter_iblk(VC1Context *v, int pq)
     }
     v->vc1dsp.vc1_v_loop_filter16(s->dest[0] + 8*s->linesize, s->linesize, pq);
 
-    if (s->mb_y == s->mb_height-1) {
+    if (s->mb_y == s->end_mb_y-1) {
         if (s->mb_x) {
             v->vc1dsp.vc1_h_loop_filter16(s->dest[0], s->linesize, pq);
             v->vc1dsp.vc1_h_loop_filter8(s->dest[1], s->uvlinesize, pq);
@@ -294,7 +294,7 @@ static void vc1_loop_filter_iblk_delayed(VC1Context *v, int 
pq)
             v->vc1dsp.vc1_v_loop_filter16(s->dest[0] - 8 * s->linesize, 
s->linesize, pq);
         }
 
-        if (s->mb_y == s->mb_height) {
+        if (s->mb_y == s->end_mb_y) {
             if (s->mb_x) {
                 if (s->mb_x >= 2)
                     v->vc1dsp.vc1_h_loop_filter16(s->dest[0] - 16 * 
s->linesize - 16, s->linesize, pq);
@@ -2329,7 +2329,7 @@ static av_always_inline void 
vc1_apply_p_v_loop_filter(VC1Context *v, int block_
     } else {
         dst      = s->dest[0] + (block_num & 1) * 8 + ((block_num & 2) * 4 - 
8) * linesize;
     }
-    if (s->mb_y != s->mb_height || block_num < 2) {
+    if (s->mb_y != s->end_mb_y || block_num < 2) {
         int16_t (*mv)[2];
         int mv_stride;
 
@@ -3095,7 +3095,7 @@ static void vc1_decode_i_blocks_adv(VC1Context *v)
         if(v->s.loop_filter) vc1_loop_filter_iblk_delayed(v, v->pq);
     }
     if (v->s.loop_filter)
-        ff_draw_horiz_band(s, (s->mb_height-1)*16, 16);
+        ff_draw_horiz_band(s, (s->end_mb_y-1)*16, 16);
     ff_er_add_slice(s, 0, s->start_mb_y, s->mb_width - 1, s->end_mb_y - 1, 
(AC_END|DC_END|MV_END));
 }
 
@@ -3218,7 +3218,7 @@ static void vc1_decode_b_blocks(VC1Context *v)
         s->first_slice_line = 0;
     }
     if (v->s.loop_filter)
-        ff_draw_horiz_band(s, (s->mb_height-1)*16, 16);
+        ff_draw_horiz_band(s, (s->end_mb_y-1)*16, 16);
     ff_er_add_slice(s, 0, s->start_mb_y, s->mb_width - 1, s->end_mb_y - 1, 
(AC_END|DC_END|MV_END));
 }
 
@@ -3226,9 +3226,9 @@ static void vc1_decode_skip_blocks(VC1Context *v)
 {
     MpegEncContext *s = &v->s;
 
-    ff_er_add_slice(s, 0, 0, s->mb_width - 1, s->mb_height - 1, 
(AC_END|DC_END|MV_END));
+    ff_er_add_slice(s, 0, s->start_mb_y, s->mb_width - 1, s->end_mb_y - 1, 
(AC_END|DC_END|MV_END));
     s->first_slice_line = 1;
-    for(s->mb_y = 0; s->mb_y < s->mb_height; s->mb_y++) {
+    for(s->mb_y = s->start_mb_y; s->mb_y < s->end_mb_y; s->mb_y++) {
         s->mb_x = 0;
         ff_init_block_index(s);
         ff_update_block_index(s);
-- 
1.7.5.1

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