libavformat/rtsp.c:903: error: Null Dereference
  pointer `st` last assigned on line 894 could be null and is dereferenced at line 903, column 56.

libavformat/rtsp.c:890:1: start of procedure rtsp_open_transport_ctx()
888. }
889. 
890. static int
     ^
891. rtsp_open_transport_ctx(AVFormatContext *s, RTSPStream *rtsp_st)
892. {

libavformat/rtsp.c:893:5: 
891. rtsp_open_transport_ctx(AVFormatContext *s, RTSPStream *rtsp_st)
892. {
893.     RTSPState *rt = s->priv_data;
         ^
894.     AVStream *st = NULL;
895. 

libavformat/rtsp.c:894:5: 
892. {
893.     RTSPState *rt = s->priv_data;
894.     AVStream *st = NULL;
         ^
895. 
896.     /* open the RTP context */

libavformat/rtsp.c:897:9: Taking false branch
895. 
896.     /* open the RTP context */
897.     if (rtsp_st->stream_index >= 0)
             ^
898.         st = s->streams[rtsp_st->stream_index];
899.     if (!st)

libavformat/rtsp.c:899:10: Taking true branch
897.     if (rtsp_st->stream_index >= 0)
898.         st = s->streams[rtsp_st->stream_index];
899.     if (!st)
              ^
900.         s->ctx_flags |= AVFMTCTX_NOHEADER;
901. 

libavformat/rtsp.c:900:9: 
898.         st = s->streams[rtsp_st->stream_index];
899.     if (!st)
900.         s->ctx_flags |= AVFMTCTX_NOHEADER;
             ^
901. 
902.     if (rt->transport == RTSP_TRANSPORT_RDT)

libavformat/rtsp.c:902:9: Taking true branch
900.         s->ctx_flags |= AVFMTCTX_NOHEADER;
901. 
902.     if (rt->transport == RTSP_TRANSPORT_RDT)
             ^
903.         rtsp_st->transport_priv = ff_rdt_parse_open(s, st->index,
904.                                             rtsp_st->dynamic_protocol_context,

libavformat/rtsp.c:903:9: 
901. 
902.     if (rt->transport == RTSP_TRANSPORT_RDT)
903.         rtsp_st->transport_priv = ff_rdt_parse_open(s, st->index,
             ^
904.                                             rtsp_st->dynamic_protocol_context,
905.                                             rtsp_st->dynamic_handler);
