IEC 60958-4-2:2016,Digital audio interface – Part 4-2: Professional applications – Metadata and subcode.
The two-channel digital audio interface has been widely used in a variety of professional audio applications that have reached beyond the vision of the original standard. In particular, applications using increased sampling frequencies and alternative physical media.
Separating the standard into independently-maintainable parts allows, for example, additional transmission media to be introduced in the future by revising lEO 60958-4-4 without affecting the other parts of the lEO 60958-4 series. The parts comprise:
Part 4-1: Audio content: defines the format for coding audio used for the audio content. It specifies the semantics of the audio data, including the “validity” flag. It also specifies the sampling frequency by reference to AES5.
Part 4-2: Metadata and subcode: specifies the format for information, metadata, or subcode transmitted with the audio data: principally the “channel status” but also user data and the auxiliary bits. Implementors will note that the current implementation options (“Standard” and “Enhanced”) both require that status data be implemented correctly in compliant equipment.
Part 4-4: Physical and electrical parameters: specifies the physical signals that convey the bit stream specified in IEC 60958-1. The transport format is intended for use with shielded twisted-pair cable of conventional design over distances of up to 100 m at frame rates of up to 50 kHz. Longer cable lengths and higher frame rates may be used, but with a rapidly increasing requirement for care in cable selection and possible receiver equalization, or the use of active repeaters. Provision is made in this standard for adapting the balanced terminals to use 75 2 coaxial cable. Transmission by fibre-optic cable is under consideration.
This part of IEC 60958 specifies the format for coding metadata, or subcode, that relates to the audio content and is carried with it. This part of IEC 60958, together with IEC 60958-1, IEC 60958-4-1, and IEC 60958-4-4, specifies an interface for serial digital transmission of two channels of periodically sampled and linearly represented digital audio data from one transmitter to one receiver.IEC 60958-4-2:2016 pdf download.