IoTGateway/BSP/Android/Gettingstarted/How to switch HDMI Audio
From ESS-WIKI
When HDMI has audio, the default output from HDMI audio only.
The following settings are set to open the other audio together.
Power on, stop at the uboot stage:
rkboot # setenv switch_hdmi_audio 1 rkboot # saveenv rkboot # reset