libavformat/utils.c:2555: error: Uninitialized Value
  The value read from ret was never initialized.

libavformat/utils.c:2555:8: 
2553.         ret = s->oformat->write_trailer(s);
2554. fail:
2555.     if(ret == 0)
             ^
2556.        ret=url_ferror(s->pb);
2557.     for(i=0;i<s->nb_streams;i++)
