4.1 Background to Dedicated Audio Interfaces

When digital audio interfaces were first introduced it was assumed that digital audio signals would need to be carried between devices on connections similar to those used for analog signals. In other words, there would need to be individual point-to-point connections between each device, carrying little other than audio and using standard connectors and cables. The AES3 interface, as described below, is a good example of such an interface. It was intended to be used in as similar a way as possible to the method used for connecting pieces of analog audio equipment together. It used XLR connectors with relatively standard cables so that existing installations could be converted to digital applications. From a practical point of view, the only practical difference was that a single connection carried two channels instead of one. Such dedicated interfaces carry one or more channels of audio data, normally sample-locked to the transmitting device's sampling rate, and operate in a real-time 'streaming' fashion. They generally do not operate using an addressing structure, and so are normally used for connections between a single transmitting device and a single receiving device (hence 'point-to-point'). This method of interconnection is still in wide use today and is likely to continue to be so for some time, but the increasing ubiquity of high-speed data networks and computer-based audio systems is likely to have an increasing effect on the way audio is carried as time goes by (see the next chapter).