libavcodec/vp3.c:828: error: Uninitialized Value
  The value read from motion_x[_] was never initialized.

libavcodec/vp3.c:828:39: 
826.                 } else if (s->chroma_x_shift) {
827.                     if (s->macroblock_coding[current_macroblock] == MODE_INTER_FOURMV) {
828.                         motion_x[0] = RSHIFT(motion_x[0] + motion_x[1], 1);
                                           ^
829.                         motion_y[0] = RSHIFT(motion_y[0] + motion_y[1], 1);
830.                         motion_x[1] = RSHIFT(motion_x[2] + motion_x[3], 1);
