libavformat/rtsp.c:717: error: Null Dereference
  pointer `st` last assigned on line 708 could be null and is dereferenced at line 717, column 56.

libavformat/rtsp.c:704:1: start of procedure rtsp_open_transport_ctx()
702. }
703. 
704. static int
     ^
705. rtsp_open_transport_ctx(AVFormatContext *s, RTSPStream *rtsp_st)
706. {

libavformat/rtsp.c:707:5: 
705. rtsp_open_transport_ctx(AVFormatContext *s, RTSPStream *rtsp_st)
706. {
707.     RTSPState *rt = s->priv_data;
         ^
708.     AVStream *st = NULL;
709. 

libavformat/rtsp.c:708:5: 
706. {
707.     RTSPState *rt = s->priv_data;
708.     AVStream *st = NULL;
         ^
709. 
710.     /* open the RTP context */

libavformat/rtsp.c:711:9: Taking false branch
709. 
710.     /* open the RTP context */
711.     if (rtsp_st->stream_index >= 0)
             ^
712.         st = s->streams[rtsp_st->stream_index];
713.     if (!st)

libavformat/rtsp.c:713:10: Taking true branch
711.     if (rtsp_st->stream_index >= 0)
712.         st = s->streams[rtsp_st->stream_index];
713.     if (!st)
              ^
714.         s->ctx_flags |= AVFMTCTX_NOHEADER;
715. 

libavformat/rtsp.c:714:9: 
712.         st = s->streams[rtsp_st->stream_index];
713.     if (!st)
714.         s->ctx_flags |= AVFMTCTX_NOHEADER;
             ^
715. 
716.     if (rt->transport == RTSP_TRANSPORT_RDT)

libavformat/rtsp.c:716:9: Taking true branch
714.         s->ctx_flags |= AVFMTCTX_NOHEADER;
715. 
716.     if (rt->transport == RTSP_TRANSPORT_RDT)
             ^
717.         rtsp_st->transport_priv = ff_rdt_parse_open(s, st->index,
718.                                             rtsp_st->dynamic_protocol_context,

libavformat/rtsp.c:717:9: 
715. 
716.     if (rt->transport == RTSP_TRANSPORT_RDT)
717.         rtsp_st->transport_priv = ff_rdt_parse_open(s, st->index,
             ^
718.                                             rtsp_st->dynamic_protocol_context,
719.                                             rtsp_st->dynamic_handler);
