libavcodec/vc1.c:3183: error: Uninitialized Value
  The value read from is_intra[_] was never initialized.

libavcodec/vc1.c:3183:17: 
3181.                 dst_idx += i >> 2;
3182.                 off = (i & 4) ? 0 : ((i & 1) * 8 + (i & 2) * 4 * s->linesize);
3183.                 s->mb_intra = is_intra[i];
                      ^
3184.                 if (is_intra[i]) {
3185.                     /* check if prediction blocks A and C are available */
