avcodec/vc1: fix mb_height for field pictures

Fixes ticket2531

Tables are always allocated now with sufficient space for either progressive
or interlaced content. The alternative would be to detect a change
and reallocate.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/vc1.c

@@ -860,12 +860,17 @@ int ff_vc1_parse_frame_header_adv(VC1Context *v, GetBitContext* gb)
     v->field_mode = field_mode;
     v->fcm = fcm;
 
+    av_assert0(    v->s.mb_height == v->s.height + 15 >> 4
+                || v->s.mb_height == FFALIGN(v->s.height + 15 >> 4, 2));
     if (v->field_mode) {
+        v->s.mb_height = FFALIGN(v->s.height + 15 >> 4, 2);
         v->fptype = get_bits(gb, 3);
         v->s.pict_type = (v->fptype & 2) ? AV_PICTURE_TYPE_P : AV_PICTURE_TYPE_I;
         if (v->fptype & 4) // B-picture
             v->s.pict_type = (v->fptype & 2) ? AV_PICTURE_TYPE_BI : AV_PICTURE_TYPE_B;
+
     } else {
+        v->s.mb_height = v->s.height + 15 >> 4;
         switch (get_unary(gb, 0, 4)) {
         case 0:
             v->s.pict_type = AV_PICTURE_TYPE_P;

libavcodec/vc1dec.c

@@ -5498,14 +5498,15 @@ av_cold int ff_vc1_decode_init_alloc_tables(VC1Context *v)
 {
     MpegEncContext *s = &v->s;
     int i;
+    int mb_height = FFALIGN(s->mb_height, 2);
 
     /* Allocate mb bitplanes */
-    v->mv_type_mb_plane = av_malloc (s->mb_stride * s->mb_height);
-    v->direct_mb_plane  = av_malloc (s->mb_stride * s->mb_height);
-    v->forward_mb_plane = av_malloc (s->mb_stride * s->mb_height);
-    v->fieldtx_plane    = av_mallocz(s->mb_stride * s->mb_height);
-    v->acpred_plane     = av_malloc (s->mb_stride * s->mb_height);
-    v->over_flags_plane = av_malloc (s->mb_stride * s->mb_height);
+    v->mv_type_mb_plane = av_malloc (s->mb_stride * mb_height);
+    v->direct_mb_plane  = av_malloc (s->mb_stride * mb_height);
+    v->forward_mb_plane = av_malloc (s->mb_stride * mb_height);
+    v->fieldtx_plane    = av_mallocz(s->mb_stride * mb_height);
+    v->acpred_plane     = av_malloc (s->mb_stride * mb_height);
+    v->over_flags_plane = av_malloc (s->mb_stride * mb_height);
 
     v->n_allocated_blks = s->mb_width + 2;
     v->block            = av_malloc(sizeof(*v->block) * v->n_allocated_blks);
@@ -5519,20 +5520,20 @@ av_cold int ff_vc1_decode_init_alloc_tables(VC1Context *v)
     v->luma_mv          = v->luma_mv_base + s->mb_stride;
 
     /* allocate block type info in that way so it could be used with s->block_index[] */
-    v->mb_type_base = av_malloc(s->b8_stride * (s->mb_height * 2 + 1) + s->mb_stride * (s->mb_height + 1) * 2);
+    v->mb_type_base = av_malloc(s->b8_stride * (mb_height * 2 + 1) + s->mb_stride * (mb_height + 1) * 2);
     v->mb_type[0]   = v->mb_type_base + s->b8_stride + 1;
-    v->mb_type[1]   = v->mb_type_base + s->b8_stride * (s->mb_height * 2 + 1) + s->mb_stride + 1;
-    v->mb_type[2]   = v->mb_type[1] + s->mb_stride * (s->mb_height + 1);
+    v->mb_type[1]   = v->mb_type_base + s->b8_stride * (mb_height * 2 + 1) + s->mb_stride + 1;
+    v->mb_type[2]   = v->mb_type[1] + s->mb_stride * (mb_height + 1);
 
     /* allocate memory to store block level MV info */
-    v->blk_mv_type_base = av_mallocz(     s->b8_stride * (s->mb_height * 2 + 1) + s->mb_stride * (s->mb_height + 1) * 2);
+    v->blk_mv_type_base = av_mallocz(     s->b8_stride * (mb_height * 2 + 1) + s->mb_stride * (mb_height + 1) * 2);
     v->blk_mv_type      = v->blk_mv_type_base + s->b8_stride + 1;
-    v->mv_f_base        = av_mallocz(2 * (s->b8_stride * (s->mb_height * 2 + 1) + s->mb_stride * (s->mb_height + 1) * 2));
+    v->mv_f_base        = av_mallocz(2 * (s->b8_stride * (mb_height * 2 + 1) + s->mb_stride * (mb_height + 1) * 2));
     v->mv_f[0]          = v->mv_f_base + s->b8_stride + 1;
-    v->mv_f[1]          = v->mv_f[0] + (s->b8_stride * (s->mb_height * 2 + 1) + s->mb_stride * (s->mb_height + 1) * 2);
-    v->mv_f_next_base   = av_mallocz(2 * (s->b8_stride * (s->mb_height * 2 + 1) + s->mb_stride * (s->mb_height + 1) * 2));
+    v->mv_f[1]          = v->mv_f[0] + (s->b8_stride * (mb_height * 2 + 1) + s->mb_stride * (mb_height + 1) * 2);
+    v->mv_f_next_base   = av_mallocz(2 * (s->b8_stride * (mb_height * 2 + 1) + s->mb_stride * (mb_height + 1) * 2));
     v->mv_f_next[0]     = v->mv_f_next_base + s->b8_stride + 1;
-    v->mv_f_next[1]     = v->mv_f_next[0] + (s->b8_stride * (s->mb_height * 2 + 1) + s->mb_stride * (s->mb_height + 1) * 2);
+    v->mv_f_next[1]     = v->mv_f_next[0] + (s->b8_stride * (mb_height * 2 + 1) + s->mb_stride * (mb_height + 1) * 2);
 
     /* Init coded blocks info */
     if (v->profile == PROFILE_ADVANCED) {
@@ -6105,6 +6106,7 @@ static int vc1_decode_frame(AVCodecContext *avctx, void *data,
                     continue;
                 }
                 v->second_field = 1;
+                av_assert0((s->mb_height & 1) == 0);
                 v->blocks_off   = s->b8_stride * (s->mb_height&~1);
                 v->mb_off       = s->mb_stride * s->mb_height >> 1;
             } else {