Also known as Dolby Digital . This term usually refers to the connector found on a DVD decoder card, or DVD player that sends the 5.1 channel Dolby Digital has 6 discrete digital audio channels: 5 seperate full-bandwidth channels (for front left and right, center, and back left and right) and 1 "low frequency effects" subwoofer channel. Some receivers have Dolby Digital decoding built-in; others are simply Dolby Digital "ready" with inputs for hooking up an external Dolby Digital decoder.