HDMI 1.4 Specification - Audio Channel Return

Minimizing the Cable Clutter

This feature of HDMI 1.4 is a significant change in the way that we think about audio. In previous versions of HDMI and other A/V cable solutions, audio traveled in only one direction, as shown in the image below. 

Notice that the HDMI cable forms a connection from the input device, such as a DVD/CD player, to the stereo speaker/tuner system. From there, another HDMI cable extends from the audio output of the tuner to the display (which allows the input device — in this case, the DVD/CD player — to still be connected directly to the display, bypassing the stereo system). But for the display to send a signal back to the audio output of the tuner, you’d need a separate cable. 

 With the Audio Return Channel, the return audio can be sent back to the audio output without a secondary cable, resulting in these benefits:

• The single-cable design does not require additional HDMI cables, since it uses the same connections and wires as before.

• Fewer cables reduces the time and cost of installation.

• The lip-synch feature is carried back over the return channel to ensure that sound matches the video.

Obviously, these benefits are expected to make ARC a very popular feature.