> Fixes #2557. > > Signed-off-by: Paul B Mahol <onemda at gmail.com> > --- > libavcodec/vc1_pred.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/libavcodec/vc1_pred.c b/libavcodec/vc1_pred.c > index 54712f6b7a..9f42a930fe 100644 > --- a/libavcodec/vc1_pred.c > +++ b/libavcodec/vc1_pred.c > @@ -98,9 +98,9 @@ static av_always_inline int scaleforsame_y(VC1Context *v, > int i, int n /* MV */, > } > > if (v->cur_field_type && !v->ref_field_type[dir]) > - return av_clip(scaledvalue, -v->range_y / 2 + 1, v->range_y / 2); > + return av_clip(scaledvalue, -v->range_y / 2 - 1, v->range_y / 2); > else > - return av_clip(scaledvalue, -v->range_y / 2, v->range_y / 2 - 1); > + return av_clip(scaledvalue, -v->range_y / 2, v->range_y / 2 + 1); > } > > static av_always_inline int scaleforopp_x(VC1Context *v, int n /* MV */) > -- > 2.11.0
scaleforsame_y references ref_field_type. Therefore, it needs to be set before scaleforsame is called. Signed-off-by: Jerome Borsboom <jerome.borsb...@carpalis.nl> --- I am not sure your patch is correct. The existing implementation agrees with VC-1 spec. See Figure 119 in 10.3.5.4.3.4.2 in particular. Please have a look if the patch below solves the issue. ref_field_type is referenced in scaleforsame_y and needs to be set earlier in ff_vc1_pred_mv to have the desired effect. libavcodec/vc1_pred.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/libavcodec/vc1_pred.c b/libavcodec/vc1_pred.c index 54712f6b7a..3a52a22bc6 100644 --- a/libavcodec/vc1_pred.c +++ b/libavcodec/vc1_pred.c @@ -341,6 +341,8 @@ void ff_vc1_pred_mv(VC1Context *v, int n, int dmv_x, int dmv_y, } else opposite = 0; if (opposite) { + v->mv_f[dir][xy + v->blocks_off] = 1; + v->ref_field_type[dir] = !v->cur_field_type; if (a_valid && !a_f) { field_predA[0] = scaleforopp(v, field_predA[0], 0, dir); field_predA[1] = scaleforopp(v, field_predA[1], 1, dir); @@ -353,9 +355,9 @@ void ff_vc1_pred_mv(VC1Context *v, int n, int dmv_x, int dmv_y, field_predC[0] = scaleforopp(v, field_predC[0], 0, dir); field_predC[1] = scaleforopp(v, field_predC[1], 1, dir); } - v->mv_f[dir][xy + v->blocks_off] = 1; - v->ref_field_type[dir] = !v->cur_field_type; } else { + v->mv_f[dir][xy + v->blocks_off] = 0; + v->ref_field_type[dir] = v->cur_field_type; if (a_valid && a_f) { field_predA[0] = scaleforsame(v, n, field_predA[0], 0, dir); field_predA[1] = scaleforsame(v, n, field_predA[1], 1, dir); @@ -368,8 +370,6 @@ void ff_vc1_pred_mv(VC1Context *v, int n, int dmv_x, int dmv_y, field_predC[0] = scaleforsame(v, n, field_predC[0], 0, dir); field_predC[1] = scaleforsame(v, n, field_predC[1], 1, dir); } - v->mv_f[dir][xy + v->blocks_off] = 0; - v->ref_field_type[dir] = v->cur_field_type; } if (a_valid) { -- 2.13.6 _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel