VC1: Support dynamic dimension changes

Fixes SA00072, SA00073, SA10150, SA10151, Issue2076

Improves SA10153
Signed-off-by: Anton Khirnov <anton@khirnov.net>

libavcodec/vc1.c

@@ -453,9 +453,6 @@ static int decode_sequence_header_adv(VC1Context *v, GetBitContext *gb)
     v->finterpflag = get_bits1(gb);
     skip_bits1(gb); // reserved
 
-    v->s.h_edge_pos = v->s.avctx->coded_width;
-    v->s.v_edge_pos = v->s.avctx->coded_height;
-
     av_log(v->s.avctx, AV_LOG_DEBUG,
                "Advanced Profile level %i:\nfrmrtq_postproc=%i, bitrtq_postproc=%i\n"
                "LoopFilter=%i, ChromaFormat=%i, Pulldown=%i, Interlace: %i\n"
@@ -474,8 +471,8 @@ static int decode_sequence_header_adv(VC1Context *v, GetBitContext *gb)
     if(get_bits1(gb)) { //Display Info - decoding is not affected by it
         int w, h, ar = 0;
         av_log(v->s.avctx, AV_LOG_DEBUG, "Display extended info:\n");
-        v->s.avctx->width  = w = get_bits(gb, 14) + 1;
-        v->s.avctx->height = h = get_bits(gb, 14) + 1;
+        w = get_bits(gb, 14) + 1;
+        h = get_bits(gb, 14) + 1;
         av_log(v->s.avctx, AV_LOG_DEBUG, "Display dimensions: %ix%i\n", w, h);
         if(get_bits1(gb))
             ar = get_bits(gb, 4);
@@ -485,6 +482,12 @@ static int decode_sequence_header_adv(VC1Context *v, GetBitContext *gb)
             w = get_bits(gb, 8) + 1;
             h = get_bits(gb, 8) + 1;
             v->s.avctx->sample_aspect_ratio = (AVRational){w, h};
+        } else {
+            av_reduce(&v->s.avctx->sample_aspect_ratio.num,
+                      &v->s.avctx->sample_aspect_ratio.den,
+                      v->s.avctx->height * w,
+                      v->s.avctx->width * h,
+                      1<<30);
         }
         av_log(v->s.avctx, AV_LOG_DEBUG, "Aspect: %i:%i\n", v->s.avctx->sample_aspect_ratio.num, v->s.avctx->sample_aspect_ratio.den);
 
@@ -552,8 +555,8 @@ int vc1_decode_entry_point(AVCodecContext *avctx, VC1Context *v, GetBitContext *
     }
 
     if(get_bits1(gb)){
-        avctx->coded_width = (get_bits(gb, 12)+1)<<1;
-        avctx->coded_height = (get_bits(gb, 12)+1)<<1;
+        avctx->width = avctx->coded_width = (get_bits(gb, 12)+1)<<1;
+        avctx->height = avctx->coded_height = (get_bits(gb, 12)+1)<<1;
     }
     if(v->extended_mv)
         v->extended_dmv = get_bits1(gb);