Chapter 4: Dedicated Audio Interfaces

Overview

For the purposes of this book, digital audio interfaces will be divided into two types. This chapter is concerned with those that are dedicated point-to-point audio interfaces (e.g. AES/EBU), designed specifically to carry audio and little else. The next chapter deals with those that are protocols running over general purpose data networks or are computer interfaces that can also carry other data (e.g. USB).

Some interfaces have been internationally standardized whereas others are associated principally with one manufacturer. Some interfaces of the latter type have become widely used by other manufacturers, either because no alternative existed at the time or in order to provide compatibility between devices. It is important to distinguish de facto standards, which have arisen because of commercial predominance, from the standards formulated by independent international bodies. Proprietary interfaces may be the subject of licences or patents, although most agree that wide adoption is beneficial for all concerned. A further subdivision of interface types is also useful, and that is between interfaces carrying one or two channels of audio data and those carrying a large number of channels.

Naturally, since standards are published and widely available, these chapters should be viewed as commentaries upon or illuminations of the published documents, together with guidelines on their implementation and discussions of the problems involved when attempting to interconnect devices digitally. Although some details of standards will be given here, readers are encouraged to read the information contained herein in conjunction with the standards documents themselves (see the references at the end of each chapter), and to note any additions or modifications to the standards which may have arisen since this book was written. As this book is designed to aid understanding of standards in real situations it is not worded like a standards document and therefore does not use the official language of such documents. It is not a substitute for the standards themselves and any intending implementer would be wise not to rely solely on the text and diagrams contained herein.