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Use correct scaling table for bwd-pred MVs in second B-field 

When scaling backward predicted MVs in second B-field, the scaling table is
opposite of that for P field pictures; i.e. first field P table will be used as
second field B table and second field P table will be used as first field B
table. This is not documented in the spec, but exists in the ref. decoder.

This fixes SA10139.

Signed-off-by: Martin Storsjö <martin@martin.st>
This commit is contained in:
Mashiat Sarker Shakkhar 2011-10-19 18:51:20 +05:00 committed by Martin Storsjö
parent 0d8506b8c5
commit 73447eb4bd
1 changed files with 11 additions and 9 deletions
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20
libavcodec/vc1dec.c
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@ -1291,6 +1291,7 @@ static av_always_inline int scaleforsame_x(VC1Context *v, int n /* MV */, int di
int scaledvalue, refdist;
int scalesame1, scalesame2;
int scalezone1_x, zone1offset_x;
int table_index = dir ^ v->second_field;
if (v->s.pict_type != AV_PICTURE_TYPE_B)
refdist = v->refdist;
@ -1298,10 +1299,10 @@ static av_always_inline int scaleforsame_x(VC1Context *v, int n /* MV */, int di
refdist = dir ? v->brfd : v->frfd;
if (refdist > 3)
refdist = 3;
scalesame1 = vc1_field_mvpred_scales[v->second_field][1][refdist];
scalesame2 = vc1_field_mvpred_scales[v->second_field][2][refdist];
scalezone1_x = vc1_field_mvpred_scales[v->second_field][3][refdist];
zone1offset_x = vc1_field_mvpred_scales[v->second_field][5][refdist];
scalesame1 = vc1_field_mvpred_scales[table_index][1][refdist];
scalesame2 = vc1_field_mvpred_scales[table_index][2][refdist];
scalezone1_x = vc1_field_mvpred_scales[table_index][3][refdist];
zone1offset_x = vc1_field_mvpred_scales[table_index][5][refdist];
if (FFABS(n) > 255)
scaledvalue = n;
@ -1323,6 +1324,7 @@ static av_always_inline int scaleforsame_y(VC1Context *v, int i, int n /* MV */,
int scaledvalue, refdist;
int scalesame1, scalesame2;
int scalezone1_y, zone1offset_y;
int table_index = dir ^ v->second_field;
if (v->s.pict_type != AV_PICTURE_TYPE_B)
refdist = v->refdist;
@ -1330,10 +1332,10 @@ static av_always_inline int scaleforsame_y(VC1Context *v, int i, int n /* MV */,
refdist = dir ? v->brfd : v->frfd;
if (refdist > 3)
refdist = 3;
scalesame1 = vc1_field_mvpred_scales[v->second_field][1][refdist];
scalesame2 = vc1_field_mvpred_scales[v->second_field][2][refdist];
scalezone1_y = vc1_field_mvpred_scales[v->second_field][4][refdist];
zone1offset_y = vc1_field_mvpred_scales[v->second_field][6][refdist];
scalesame1 = vc1_field_mvpred_scales[table_index][1][refdist];
scalesame2 = vc1_field_mvpred_scales[table_index][2][refdist];
scalezone1_y = vc1_field_mvpred_scales[table_index][4][refdist];
zone1offset_y = vc1_field_mvpred_scales[table_index][6][refdist];
if (FFABS(n) > 63)
scaledvalue = n;
@ -1444,7 +1446,7 @@ static av_always_inline int scaleforopp(VC1Context *v, int n /* MV */,
refdist = FFMIN(v->refdist, 3);
else
refdist = dir ? v->brfd : v->frfd;
scaleopp = vc1_field_mvpred_scales[v->second_field][0][refdist];
scaleopp = vc1_field_mvpred_scales[dir ^ v->second_field][0][refdist];
return n * scaleopp >> 8;
}