libavcodec/vc1.c:649: error: Uninitialized Value
  The value read from mvy[_] was never initialized.

libavcodec/vc1.c:649:14: 
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
651.         switch(idx) {
