IEC 60974-1-2021 Digital audio interface – Part 1: General.
This part of IEC 60958 describes a serial, uni-directional, self-clocking interface for the interconnection of digital audio equipment for consumer and professional applications.
It provides the basic structure of the interface. Separate documents define items specific to particular applications.
The interface is primarily intended to carry monophonic or stereophonic programmes, encoded using linear PCM and with a resolution of up to 24 bits per sample.
When used for other purposes, the interface is able to carry audio data coded other than as linear PCM coded audio samples. Provision is also made to allow the interface to carry data related to computer software, multimedia technologies, or signals coded using non-linear PCM.
The format specification for these applications is not part of this document.
The interface is intended for operation at audio sampling frequencies of 32 kHz and above.
Auxiliary information is transmitted along with the programme.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies.
For undated references, the latest edition of the referenced document (including any amendments) applies.
IEC 60268-1 1 :1 987, Sound system equipment – Part 11: Application of connectors for the interconnection of sound system components
IEC 60958-3, Digital audio interface – Part 3: Consumer applications
IEC 60958-4 (all parts), Digital audio interface – Part 4: Professional applications
IEC 60958-5, Digital audio interface – Part 5: Consumer application enhancement
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
• IEC Electropedia: available at
• ISO Online browsing platform: available at
3.1sampling frequency
frequency of the samples representing an audio signal
3.2 audio sample word
value of a digital audio sample; representation is linear in 2’s complement binary form
Note 1 to entry: Positive numbers correspond to positive analogue voltages at the input of the analogue-to-digital converter (ADC).
3.3 auxiliary sample bit
four least significant bits (LSBs) which can be assigned as auxiliary sample bits and used for auxiliary information when the number of audio sample bits in the main data field is less than or equal to 20
3.4 validity bit
bit indicating whether the main data field bits in the sub-frame (time slots 4 to 27 or 8 to 27, depending on the audio word length as described in 4.1 .1 ) are reliable or not
3.5 channel status
data carrying, in a fixed format, information associated with each main data field channel which is decodable by any interface user.IEC 60974-1 pdf download.