IEC 61937-10:2017

Overview

IEC 61937-10:2017 defines how to carry non-linear PCM audio bitstreams encoded with the MPEG‑4 Audio Lossless Coding (ALS) format over the IEC 60958 digital audio interface. Part of the IEC 61937 series, this second edition (2017) is a technical revision that extends support for additional ALS Simple Profile levels and adds metadata handling for LATM/LOAS-wrapped ALS streams. The standard specifies burst mapping, burst-info fields, payload format and timing/latency considerations needed for reliable transport and synchronization.

Key Topics

• Mapping onto IEC 61937: Rules for packaging MPEG‑4 ALS frames into IEC 61937 data-bursts so legacy IEC 60958 interfaces can transport lossless ALS bitstreams.
• Burst‑info (16‑bit field): Definition of the 16‑bit burst-info word including data-type bits 0–4, data-type bits 5–6, an error flag and ALS‑specific fields (multiplier, Simple Profile Level). Table mappings indicate when ALS or LATM/LOAS is used.
• Burst payload format: Normative description of the ALS burst payload and optional LATM/LOAS header handling; includes ALSSpecificConfig and auxiliary data fields required to decode each burst.
• ALS Simple Profile levels: Addition of Levels 2, 3 and 4 to support higher complexity/use cases while retaining Simple Profile restrictions.
• Timing and latency: Guidance on decoder latency, repetition periods of data‑bursts, IEC 60958 frame rates and how to schedule bursts for AV synchronization.
• Constraints and profiles: Limits on channels, sampling rates and word length implied by the ALS Simple Profile (referenced normative limits in the standard).

Applications and Users

Practical applications include:

• Transporting lossless multichannel audio over consumer and professional S/PDIF or AES3 links that implement IEC 60958.
• Interoperability between external decoders, AV receivers, set‑top boxes, DACs and content sources using MPEG‑4 ALS.
• Supporting LATM/LOAS-based multiplexing scenarios where ALS elementary streams are wrapped before transmission.

Who uses this standard:

• Hardware and firmware engineers designing digital audio interfaces and receivers.
• Systems integrators and manufacturers of broadcast, pro‑audio and consumer A/V equipment.
• Test labs and QA teams validating compliance and interoperability of IEC 61937 transports.

Related Standards

• IEC 60958-1 / IEC 60958-3 - Digital audio interface (general and consumer).
• IEC 61937-1 / IEC 61937-2 - General and burst-info rules for IEC 61937 series.
• ISO/IEC 14496-3 (MPEG‑4 Audio) - ALS Simple Profile and LATM/LOAS transport.

Keywords: IEC 61937-10, MPEG‑4 ALS, IEC 60958, digital audio interface, non-linear PCM, LATM/LOAS, burst-info, burst-payload, ALS Simple Profile.