libavcodec/vc1.c:3184: error: Uninitialized Value
  The value read from is_intra[_] was never initialized.

libavcodec/vc1.c:3184:21: 
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 */
3186.                     v->a_avail = v->c_avail = 0;
