libavformat/rtsp.c:617: error: Null Dereference
  pointer `st` last assigned on line 608 could be null and is dereferenced at line 617, column 56.

libavformat/rtsp.c:605:1: start of procedure rtsp_open_transport_ctx()
603. }
604. 
605. static int rtsp_open_transport_ctx(AVFormatContext *s, RTSPStream *rtsp_st)
     ^
606. {
607.     RTSPState *rt = s->priv_data;

libavformat/rtsp.c:607:5: 
605. static int rtsp_open_transport_ctx(AVFormatContext *s, RTSPStream *rtsp_st)
606. {
607.     RTSPState *rt = s->priv_data;
         ^
608.     AVStream *st = NULL;
609. 

libavformat/rtsp.c:608:5: 
606. {
607.     RTSPState *rt = s->priv_data;
608.     AVStream *st = NULL;
         ^
609. 
610.     /* open the RTP context */

libavformat/rtsp.c:611:9: Taking false branch
609. 
610.     /* open the RTP context */
611.     if (rtsp_st->stream_index >= 0)
             ^
612.         st = s->streams[rtsp_st->stream_index];
613.     if (!st)

libavformat/rtsp.c:613:10: Taking true branch
611.     if (rtsp_st->stream_index >= 0)
612.         st = s->streams[rtsp_st->stream_index];
613.     if (!st)
              ^
614.         s->ctx_flags |= AVFMTCTX_NOHEADER;
615. 

libavformat/rtsp.c:614:9: 
612.         st = s->streams[rtsp_st->stream_index];
613.     if (!st)
614.         s->ctx_flags |= AVFMTCTX_NOHEADER;
             ^
615. 
616.     if (rt->transport == RTSP_TRANSPORT_RDT)

libavformat/rtsp.c:616:9: Taking true branch
614.         s->ctx_flags |= AVFMTCTX_NOHEADER;
615. 
616.     if (rt->transport == RTSP_TRANSPORT_RDT)
             ^
617.         rtsp_st->transport_priv = ff_rdt_parse_open(s, st->index,
618.                                             rtsp_st->dynamic_protocol_context,

libavformat/rtsp.c:617:9: 
615. 
616.     if (rt->transport == RTSP_TRANSPORT_RDT)
617.         rtsp_st->transport_priv = ff_rdt_parse_open(s, st->index,
             ^
618.                                             rtsp_st->dynamic_protocol_context,
619.                                             rtsp_st->dynamic_handler);
