一个二选一的多路选择器，两个输入信号分别是不同频率的音频信号，选择信号由按键来触发，输出的信号输入到扬声器中

大华视频监控实时浏览视频，根据需要选择录制器的各个通道来实时监控，也可以同时监控多路视频。-Dahua video monitor real-time view video, you need to select the recording device according to the various channels to real-time monitoring, you can also monitor multiple video.