libavcodec/h264_direct.c:401: error: Uninitialized Value
  The value read from mv[_] was never initialized.

libavcodec/h264_direct.c:401:13: 
399.         } else {
400.             a = mv[0];
401.             b = mv[1];
                 ^
402.         }
403.         fill_rectangle(&sl->mv_cache[0][scan8[0]], 4, 4, 8, a, 4);
