Overview
IEC 62365:2009 - Digital audio: Transmission of digital audio over ATM networks defines a standardized method to carry multiple channels of professional digital audio (linear PCM or IEC 60958-4 format) over Asynchronous Transfer Mode (ATM) networks. The standard specifies how audio samples are packed into ATM cells, how audio call setup and management are signalled, and how format and control information are exchanged between endpoints. This edition (2009, bilingual version 2012-08) supersedes the 2004 edition and aligns ATM audio transport with ITU‑T Recommendation I.150.
Key topics and technical requirements
- Audio data format and packing
- Defines subframes, audio sample words, ancillary data and protocol overhead.
- Describes packing schemes, temporal grouping, multi‑channel support and grouping by channel.
- ATM cell structure
- Uses ATM cells (typical 5‑byte header + 48 data bytes) and virtual channel identifiers (VCI) to associate cells with audio calls.
- Call signalling and control
- Specifies use of ATM switched virtual circuits (SVCs) and permanent virtual circuits (PVCs).
- Defines information elements for SETUP, ADD PARTY and disconnection messages and the required responses for audio call establishment.
- Coding and timing
- Covers coding-related qualifying information, sampling frequency handling and packing of subframes into cells.
- Targets low latency and low jitter transport suitable for professional audio (the standard notes examples such as dual‑channel IEC 60958‑4 at 48 kHz producing inter‑cell times comparable to ISDN frame intervals).
- Management and protection
- Defines a management interface (message encapsulation, message types, status messages) and informative annexes on data protection and application identifiers.
- Interoperability
- References ATM adaptation layer options and ATM Forum/ITU recommendations for physical and signaling interworking.
Practical applications
- Low‑latency, high‑quality distribution of professional audio over metropolitan or wide‑area networks.
- Broadcast contribution and remote production links, studio‑to‑studio interconnections, and point‑to‑multipoint audio distribution where deterministic latency and tight timing are required.
- Use cases that require call setup, channel negotiation and per‑call audio format signaling across ATM infrastructure.
Who should use this standard
- Broadcast and pro‑audio equipment manufacturers integrating networked audio transport.
- Systems integrators and network engineers deploying professional audio over ATM.
- Standards developers and test labs validating ATM audio interoperability.
- Network operators providing guaranteed QoS for professional media services.
Related standards and references
- IEC 60958‑4 (digital audio format)
- ITU‑T Recommendation I.150 (ATM layer service)
- ATM Forum specifications (physical layer and abbreviations)
- Context: SONET/SDH, ISDN and IP/RSVP are discussed as networking alternatives in the standard.