Callback executed when a connection is opened to the server.
        Handles streaming of audio to the server.

        :param ws: Websocket client

def on_open(self, ws):
        """
        Callback executed when a connection is opened to the server.
        Handles streaming of audio to the server.

        :param ws: Websocket client
        """
        self.callback.on_connected()

        # Send initialization message
        init_data = self.build_start_message(self.options)
        self.ws_client.send(json.dumps(init_data).encode('utf8'), websocket.ABNF.OPCODE_TEXT)