libavcodec/vc1dec.c:3750: error: Uninitialized Value
  The value read from is_intra[_] was never initialized.

libavcodec/vc1dec.c:3750:21: 
3748.                 off         = (i & 4) ? 0 : ((i & 1) * 8 + (i & 2) * 4 * s->linesize);
3749.                 s->mb_intra = is_intra[i];
3750.                 if (is_intra[i]) {
                          ^
3751.                     /* check if prediction blocks A and C are available */
3752.                     v->a_avail = v->c_avail = 0;
