code: def mjpg_stream(self, channelno=None, typeno=None, path_file=None):
          
          cmd = self.mjpeg_url(channelno=channelno, typeno=typeno)
          ret = self.command(cmd)
  
          if path_file:
              with open(path_file, 'wb') as out_file:
                  shutil.copyfileobj(ret.raw, out_file)
  
          return ret.raw
docs: 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)