libavcodec/vc1dec.c:1907: error: Uninitialized Value
  The value read from px was never initialized.

libavcodec/vc1dec.c:1907:22: 
1905. 
1906.     /* store MV using signed modulus of MV range defined in 4.11 */
1907.     s->mv[0][n][0] = s->current_picture.f.motion_val[0][xy][0] = ((px + dmv_x + r_x) & ((r_x << 1) - 1)) - r_x;
                           ^
1908.     s->mv[0][n][1] = s->current_picture.f.motion_val[0][xy][1] = ((py + dmv_y + r_y) & ((r_y << 1) - 1)) - r_y;
1909.     if(mvn == 1) { /* duplicate motion data for 1-MV block */
