libavcodec/vp3.c:750: error: Uninitialized Value
  The value read from motion_x[_] was never initialized.

libavcodec/vp3.c:750:35: 
748.             if (s->chroma_y_shift) {
749.                 if (s->macroblock_coding[current_macroblock] == MODE_INTER_FOURMV) {
750.                     motion_x[0] = RSHIFT(motion_x[0] + motion_x[1] + motion_x[2] + motion_x[3], 2);
                                       ^
751.                     motion_y[0] = RSHIFT(motion_y[0] + motion_y[1] + motion_y[2] + motion_y[3], 2);
752.                 }
