libavformat/rtsp.c:613: error: Null Dereference
  pointer `st` last assigned on line 604 could be null and is dereferenced at line 613, column 56.

libavformat/rtsp.c:601:1: start of procedure rtsp_open_transport_ctx()
599. }
600. 
601. static int rtsp_open_transport_ctx(AVFormatContext *s, RTSPStream *rtsp_st)
     ^
602. {
603.     RTSPState *rt = s->priv_data;

libavformat/rtsp.c:603:5: 
601. static int rtsp_open_transport_ctx(AVFormatContext *s, RTSPStream *rtsp_st)
602. {
603.     RTSPState *rt = s->priv_data;
         ^
604.     AVStream *st = NULL;
605. 

libavformat/rtsp.c:604:5: 
602. {
603.     RTSPState *rt = s->priv_data;
604.     AVStream *st = NULL;
         ^
605. 
606.     /* open the RTP context */

libavformat/rtsp.c:607:9: Taking false branch
605. 
606.     /* open the RTP context */
607.     if (rtsp_st->stream_index >= 0)
             ^
608.         st = s->streams[rtsp_st->stream_index];
609.     if (!st)

libavformat/rtsp.c:609:10: Taking true branch
607.     if (rtsp_st->stream_index >= 0)
608.         st = s->streams[rtsp_st->stream_index];
609.     if (!st)
              ^
610.         s->ctx_flags |= AVFMTCTX_NOHEADER;
611. 

libavformat/rtsp.c:610:9: 
608.         st = s->streams[rtsp_st->stream_index];
609.     if (!st)
610.         s->ctx_flags |= AVFMTCTX_NOHEADER;
             ^
611. 
612.     if (rt->transport == RTSP_TRANSPORT_RDT)

libavformat/rtsp.c:612:9: Taking true branch
610.         s->ctx_flags |= AVFMTCTX_NOHEADER;
611. 
612.     if (rt->transport == RTSP_TRANSPORT_RDT)
             ^
613.         rtsp_st->transport_priv = ff_rdt_parse_open(s, st->index,
614.                                             rtsp_st->dynamic_protocol_context,

libavformat/rtsp.c:613:9: 
611. 
612.     if (rt->transport == RTSP_TRANSPORT_RDT)
613.         rtsp_st->transport_priv = ff_rdt_parse_open(s, st->index,
             ^
614.                                             rtsp_st->dynamic_protocol_context,
615.                                             rtsp_st->dynamic_handler);
