libavcodec/vp3.c:818: error: Uninitialized Value
  The value read from motion_y[_] was never initialized.

libavcodec/vp3.c:818:39: 
816.                         motion_x[0] = RSHIFT(motion_x[0] + motion_x[1] +
817.                                              motion_x[2] + motion_x[3], 2);
818.                         motion_y[0] = RSHIFT(motion_y[0] + motion_y[1] +
                                           ^
819.                                              motion_y[2] + motion_y[3], 2);
820.                     }
