Overview
IEC 61937-12:2010 defines how the IEC 60958 digital audio interface conveys non-linear PCM bitstreams encoded in the DRA (Digital Rise Audio) formats. This part of the IEC 61937 series specifies the structure and timing of DRA data-bursts, burst-info coding, methods to fill stream gaps, and decoding latency expectations. It is the international method for carrying DRA-encoded audio over standard consumer digital audio interfaces.
Key topics and technical requirements
- Data-burst structure: DRA data-bursts consist of a 64-bit preamble, a burst-payload containing one complete DRA frame, and stuffing bits as required. The DRA frame normally represents 1 024 samples per encoded channel; half-rate and quarter-rate variants represent larger sample groupings.
- Burst-info (Pc) coding: A 16-bit burst-info word identifies data-type, sub-data-type and format-specific bits (notably bits 8–9), which indicate the relation between DRA sampling frequency and the IEC 60958 frame rate (regular, half-rate low sampling frequency, quarter-rate).
- Repetition periods: Regular DRA data-bursts are spaced so each reference point (bit 0 of Pa) recurs every 1 024 IEC 60958 frames (for regular-rate DRA). For pause data-bursts the recommended repetition periods are 32 frames (regular), 64 frames (half-rate), and 128 frames (quarter-rate).
- Latency and timing: Latency is defined as the sum of receiving delay and decoding delay. Example values in the standard show a typical decoding delay of one DRA frame (≈21.333 ms) and an illustrative receiving delay giving a combined latency of about 24.04 ms at certain bit rates; an absolute maximum example latency is ≈42.63 ms under worst-case burst length conditions.
- Stream-gap handling: The standard prescribes use of pause data-bursts to fill transmission gaps and defines how the decoder should interpret gap-length parameters.
Applications and who uses it
IEC 61937-12:2010 is intended for:
- Consumer electronics manufacturers (AV receivers, set-top boxes, Blu-ray/DVD players) implementing IEC 60958 outputs that must carry DRA-encoded audio.
- Pro-audio and broadcast equipment designers integrating digital audio interfaces that support non-linear PCM/DRA streams.
- Firmware and software developers implementing transport layer handling, burst scheduling, and decoder synchronization for DRA.
- Systems requiring precise audio–video synchronization, deterministic burst timing, and explicit latency budgeting.
Related standards
- IEC 60958 (Digital audio interface) - transport physical/content interface
- IEC 61937 (all parts) - general method for non-linear PCM on IEC 60958
- IEC 61937-1:2007 - General rules for burst and burst-info
- IEC 61937-2 - Burst-info specifics
- GB/T 22726-2008 - referenced DRA frame specification
Keywords: IEC 61937-12:2010, DRA formats, digital audio interface, IEC 60958, non-linear PCM, data-burst, burst-info, latency, pause data-burst, sampling frequency.
Open preview (PDF)Digital audio - Interface for non-linear PCM encoded audio bitstreams applying IEC 60958 - Part 12: Non-linear PCM bitstreams according to the DRA formats
