1. Check whether the channel switching of the matrix is correct or whether the control instruction is sent correctly.
2. Check whether the current audio mode of HDMI input channel is embedded audio, and modify the audio mode of HDMI input by sending corresponding instructions according to the instruction manual.
3. If the signal source is the computer, check whether the output channel of the sound card is HDMI. Generally, select the playback device in the sound setting of the computer system, and then set the HDMI audio device as the default.