warning: incompatible
      pointer types assigning to 'me_cmp_func' (aka 'int (*)(struct
      MpegEncContext *, uint8_t *, uint8_t *, ptrdiff_t, int)') from 'int
      (MpegEncContext *, uint8_t *, uint8_t *, int, int)'
      [-Wincompatible-pointer-types]