Introduction Obviously, the electrical representation of sound information happened before the electrical representation of visual information and so did the services that used that representation to distribute sound information. The digital representation of audio, too, happened at different times than video's. In the early 1980s the Compact Disc (CD) allowed record companies to distribute digital audio for the consumer market, while the D1 digital tape, available in the late 1980’s, was for the exclusive use of professional applications such as…