libavcodec/vc1dec.c:3720: error: Uninitialized Value
  The value read from is_intra[_] was never initialized.

libavcodec/vc1dec.c:3720:36: 
3718.                 v->mb_type[0][s->block_index[i]] = is_intra[i];
3719.                 if (!coded_inter)
3720.                     coded_inter = !is_intra[i] & is_coded[i];
                                         ^
3721.             }
3722.             // if there are no coded blocks then don't do anything more
