libavcodec/error_resilience.c:617: error: Uninitialized Value
  The value read from prev_x was never initialized.

libavcodec/error_resilience.c:617:24: 
615. 
616. 
617.                     if(s->mv[0][0][0] != prev_x || s->mv[0][0][1] != prev_y){
                            ^
618.                         fixed[mb_xy]=MV_CHANGED;
619.                         changed++;
