libavformat/rtsp.c:923: error: Null Dereference
  pointer `st` last assigned on line 914 could be null and is dereferenced at line 923, column 56.

libavformat/rtsp.c:910:1: start of procedure rtsp_open_transport_ctx()
908. }
909. 
910. static int
     ^
911. rtsp_open_transport_ctx(AVFormatContext *s, RTSPStream *rtsp_st)
912. {

libavformat/rtsp.c:913:5: 
911. rtsp_open_transport_ctx(AVFormatContext *s, RTSPStream *rtsp_st)
912. {
913.     RTSPState *rt = s->priv_data;
         ^
914.     AVStream *st = NULL;
915. 

libavformat/rtsp.c:914:5: 
912. {
913.     RTSPState *rt = s->priv_data;
914.     AVStream *st = NULL;
         ^
915. 
916.     /* open the RTP context */

libavformat/rtsp.c:917:9: Taking false branch
915. 
916.     /* open the RTP context */
917.     if (rtsp_st->stream_index >= 0)
             ^
918.         st = s->streams[rtsp_st->stream_index];
919.     if (!st)

libavformat/rtsp.c:919:10: Taking true branch
917.     if (rtsp_st->stream_index >= 0)
918.         st = s->streams[rtsp_st->stream_index];
919.     if (!st)
              ^
920.         s->ctx_flags |= AVFMTCTX_NOHEADER;
921. 

libavformat/rtsp.c:920:9: 
918.         st = s->streams[rtsp_st->stream_index];
919.     if (!st)
920.         s->ctx_flags |= AVFMTCTX_NOHEADER;
             ^
921. 
922.     if (rt->transport == RTSP_TRANSPORT_RDT)

libavformat/rtsp.c:922:9: Taking true branch
920.         s->ctx_flags |= AVFMTCTX_NOHEADER;
921. 
922.     if (rt->transport == RTSP_TRANSPORT_RDT)
             ^
923.         rtsp_st->transport_priv = ff_rdt_parse_open(s, st->index,
924.                                             rtsp_st->dynamic_protocol_context,

libavformat/rtsp.c:923:9: 
921. 
922.     if (rt->transport == RTSP_TRANSPORT_RDT)
923.         rtsp_st->transport_priv = ff_rdt_parse_open(s, st->index,
             ^
924.                                             rtsp_st->dynamic_protocol_context,
925.                                             rtsp_st->dynamic_handler);
