docs: def _on_message(self, bus, message):  # pylint: disable=unused-argument
          """When a message is received from Gstreamer."""
          if message.type == Gst.MessageType.EOS:
              self.stop()
          elif message.type == Gst.MessageType.ERROR:
              self.stop()
              err, _ = message.parse_error()
              _LOGGER.error('%s', err)