libavcodec/vp3.c:753: error: Uninitialized Value
  The value read from motion_x[_] was never initialized.

libavcodec/vp3.c:753:17: 
751.                     motion_y[0] = RSHIFT(motion_y[0] + motion_y[1] + motion_y[2] + motion_y[3], 2);
752.                 }
753.                 motion_x[0] = (motion_x[0]>>1) | (motion_x[0]&1);
                     ^
754.                 motion_y[0] = (motion_y[0]>>1) | (motion_y[0]&1);
755.                 frag = s->all_fragments + mb_y*s->fragment_width[1] + mb_x;
