libavcodec/vc1.c:662: error: Uninitialized Value
  The value read from mvy[_] was never initialized.

libavcodec/vc1.c:662:18: 
660.         case 0x4:
661.             tx = mid_pred(mvx[0], mvx[1], mvx[3]);
662.             ty = mid_pred(mvy[0], mvy[1], mvy[3]);
                      ^
663.             break;
664.         case 0x8:
