Return audio layer
Return Audio Layer creates the ability to send two different multichannel audio streams, one from source to display and another, a return channel in the opposite direction. Audio Return Channel (ARC) was introduced by the HDMI 1.4.standard. This S/PDIF signal is sent in the opposite direction to the video signals. Usually displays send ARC to source devices ‑ typically TV sound to audio receivers, or microphone sound from headsets to computers.