libavcodec/vc1.c:648: error: Uninitialized Value
  The value read from mvx[_] was never initialized.

libavcodec/vc1.c:648:14: 
646.     idx = (intra[3] << 3) | (intra[2] << 2) | (intra[1] << 1) | intra[0];
647.     if(!idx) { // all blocks are inter
648.         tx = median4(mvx[0], mvx[1], mvx[2], mvx[3]);
                  ^
649.         ty = median4(mvy[0], mvy[1], mvy[2], mvy[3]);
650.     } else if(count[idx] == 1) { // 3 inter blocks
