AES Standards News Blog

A Call for Comment on DRAFT REVISED AES3, AES standard for digital audio — Digital input-output interfacing — Serial transmission format for two-channel linearly represented digital audio data, has been published at http://www.aes.org/standards/comments/

AES3 has been under constant review since the standard was first issued in 1985. The present revision - divided into four complementary parts to simplify implementation over an increasingly wide range of application - reflects the collective experience and opinions of many users, manufacturers, and organizations familiar with equipment or systems employing AES3.

Part 1 defines the format for coding audio used for the audio content.

Part 2 specifies the format for information, metadata, or subcode transmitted with the audio data: principally the "channel status" but also user data and the use of the auxiliary bits to carry a co-ordination signal.

Part 3 specifies the framing and channel coding for transmission on a unidirectional point-to-point physical link. The specified format minimizes the direct-current (DC) component on the transmission line, facilitates clock recovery from the data stream, and makes the interface insensitive to the polarity of connections. 

Part 4 specifies the physical signals that convey the bit stream specified in Part 3. The current revision covers electrical signals on twisted-pair and co-axial cables. Other media, including fibre optic connections, are under consideration.  

Separating AES3 into independently maintainable parts in this way would allow, for example, the revision of part 4 to introduce additional media in the future without affecting the other parts of AES3. Interfaces would also be able to claim compliance with AES3-1 to AES3-3 even though they use physical and electrical techniques beyond those described in part 4. Its technical content is believed to be consistent with the relevant parts of the 2003 edition as amended by Amendments 5 and 6. The language has been reviewed to remove potential ambiguities— occasionally introduced because modern technology now offers many more options that were historically available—and to improve readability.

Because the contents of these four documents are related, they are published for comment as a set. Any comments arising will be considered for each document independently.