libavcodec/vc1_block.c:1488: error: Uninitialized Value
  The value read from is_intra[_] was never initialized.

libavcodec/vc1_block.c:1488:17: 
1486.                 if (i == 4)
1487.                     ff_vc1_mc_4mv_chroma(v, 0);
1488.                 v->mb_type[0][s->block_index[i]] = is_intra[i];
                      ^
1489.                 if (!coded_inter)
1490.                     coded_inter = !is_intra[i] & is_coded[i];
