libavformat/rtsp.c:616: error: Null Dereference
  pointer `st` last assigned on line 607 could be null and is dereferenced at line 616, column 56.

libavformat/rtsp.c:604:1: start of procedure rtsp_open_transport_ctx()
602. }
603. 
604. static int rtsp_open_transport_ctx(AVFormatContext *s, RTSPStream *rtsp_st)
     ^
605. {
606.     RTSPState *rt = s->priv_data;

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

libavformat/rtsp.c:607:5: 
605. {
606.     RTSPState *rt = s->priv_data;
607.     AVStream *st = NULL;
         ^
608. 
609.     /* open the RTP context */

libavformat/rtsp.c:610:9: Taking false branch
608. 
609.     /* open the RTP context */
610.     if (rtsp_st->stream_index >= 0)
             ^
611.         st = s->streams[rtsp_st->stream_index];
612.     if (!st)

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

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

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

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