libavcodec/h264.c:2940: error: Uninitialized Value
  The value read from len[_] was never initialized.

libavcodec/h264.c:2940:24: 
2938.             if(list && len[0] > 1 && len[0] == len[1])
2939.                 for(i=0; h->default_ref_list[0][i].data[0] == h->default_ref_list[1][i].data[0]; i++)
2940.                     if(i == len[0]){
                             ^
2941.                         FFSWAP(Picture, h->default_ref_list[1][0], h->default_ref_list[1][1]);
2942.                         break;
