libavcodec/h264_direct.c:321: error: Uninitialized Value
  The value read from mv[_] was never initialized.

libavcodec/h264_direct.c:321:21: 
319.                 a=b=0;
320.                 if(ref[0] > 0)
321.                     a= mv[0];
                         ^
322.                 if(ref[1] > 0)
323.                     b= mv[1];
