code: def rtsp_url(self, channelno=None, typeno=None):
          
          if channelno is None:
              channelno = 1
  
          if typeno is None:
              typeno = 0
  
          cmd = 'cam/realmonitor?channel={0}&subtype={1}'.format(
              channelno, typeno)
  
          try:
              port = ':' + [x.split('=')[1] for x in self.rtsp_config.split()
                            if x.startswith('table.RTSP.Port=')][0]
          except IndexError:
              port = ''
          return 'rtsp://{}:{}@{}{}/{}'.format(
              self._user, self._password, self._host, port, cmd)
docs: Return RTSP streaming url
  
          Params:
              channelno: integer, the video channel index which starts from 1,
                         default 1 if not specified.
  
              typeno: the stream type, default 0 if not specified. It can be
                      the following value:
  
                      0-Main Stream
                      1-Extra Stream 1 (Sub Stream)
                      2-Extra Stream 2 (Sub Stream)