The HDMI-ARC module connects to a TV via HDMI cable for the audio signal and the volume is adjusted by remote control of the TV. The module is automatically detected by the TV (for HDMI 1.3). The TV then sends volume commands to the module, which will then pass it through to a host uC in an audio device (e.g. streamer, amplifier etc.).
The audio signal is sent to a host device in S/P-DIF or I2S format. The CEC information is then sent to a host uC via I2C.