Merge commit '5e25fdbf'

* commit '5e25fdbf':
  vc1dec: Make sure last_picture is initialized in vc1_decode_skip_blocks

See: 09de0ffeMerged-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/vc1dec.c

@@ -5155,17 +5155,18 @@ static void vc1_decode_skip_blocks(VC1Context *v)
 {
     MpegEncContext *s = &v->s;
 
+    if (!v->s.last_picture.f.data[0])
+        return;
+
     ff_er_add_slice(&s->er, 0, s->start_mb_y, s->mb_width - 1, s->end_mb_y - 1, ER_MB_END);
     s->first_slice_line = 1;
     for (s->mb_y = s->start_mb_y; s->mb_y < s->end_mb_y; s->mb_y++) {
         s->mb_x = 0;
         init_block_index(v);
         ff_update_block_index(s);
-        if (s->last_picture.f.data[0]) {
         memcpy(s->dest[0], s->last_picture.f.data[0] + s->mb_y * 16 * s->linesize,   s->linesize   * 16);
         memcpy(s->dest[1], s->last_picture.f.data[1] + s->mb_y *  8 * s->uvlinesize, s->uvlinesize *  8);
         memcpy(s->dest[2], s->last_picture.f.data[2] + s->mb_y *  8 * s->uvlinesize, s->uvlinesize *  8);
-        }
         ff_mpeg_draw_horiz_band(s, s->mb_y * 16, 16);
         s->first_slice_line = 0;
     }