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The digital audio format established by the AES (Audio Engineering Society) and EBU (European Broadcasting Union) that is used to transfer digital audio data between professional equipment. Two channels of digital audio (left/odd and right/even) are carried in one connection, usually an XLR-type connection.

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AES/EBU Format

The low-level protocol for data transmission in AES/EBU and S/PDIF is largely identical, and the following discussion applies for S/PDIF as well unless otherwise noted.

AES/EBU was designed primarily to support PCM encoded audio in either DAT format at 48 kHz or CD format at 44.1 kHz. No attempt was made to use a carrier able to support both rates; instead, AES/EBU allows the data to be run at any rate, and recovers the clock rate by encoding the data using biphase mark code (BMC).

The AES3 standard parallels part 4 of the international standard IEC 60958. Of the physical interconnection types defined by IEC 60958, three are in common use:

* IEC 60958 Type I Balanced – 3-conductor, 110-ohm twisted pair cabling with an XLR connector, used in professional installations (AES3 standard)
* IEC 60958 Type II Unbalanced – 2-conductor, 75-ohm coaxial cable with an RCA connector, used in consumer audio
* IEC 60958 Type II Optical – optical fiber, usually plastic but occasionally glass, with an F05 connector, also used in consumer audio

The AES-3id standard defines a 75-ohm BNC electrical variant of AES3. More recently, professional equipment (notably by Sony) has used this physical interconnection type. This uses the same cabling, patching and infrastructure as analog or digital video, and is thus common in the broadcast industry.

F05 connectors, 5 mm connectors for plastic optical fiber, are more commonly known by their Toshiba brand name, TOSLINK. The precursor of the IEC 60958 Type II specification was the Sony/Philips Digital Interface, or S/PDIF. For details on the format of AES/EBU data, see the article on S/PDIF. Note that the electrical levels differ between AES/EBU and S/PDIF.

For information on the synchronization of digital audio structures, see the AES11 standard. The ability to insert unique identifiers into an AES3 bit stream is covered by the AES52 standard.

Other AES3 transport structures.

AES3 digital audio format can also be carried over an Asynchronous Transfer Mode network. The standard for packing AES3 frames into ATM cells is AES47, and is also published as IEC 62365. This requires a CAT5 or CAT6 type of network infrastructure to support this.

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