A/342 Part 2, “AC-4 System”Approved: 14 April 2026

This document standardizes the AC-4 audio system for use in the ATSC 3.0 Digital Television System. It describes the characteristics of the AC-4 audio system and establishes a set of constraints on ETSI TS 103 190-2 for use within ATSC 3.0 broadcast emissions. The ATSC 3.0 audio system provides an enhanced feature set and improves upon the capabilities of past ATSC audio systems. The system provides listeners with both a personalized and an immersive experience. The ATSC 3.0 audio system establishes a common framework for multiple Next Generation Audio (NGA) systems, both current and future. The AC-4 audio system is one of the NGA systems standardized in ATSC 3.0.

Download current version: A/342:2026-04 Part 2, “AC-4 System”, 14 April 2026. This version of the Standard is normatively referenced in A/300:2026-04.

Previous Versions

There are multiple versions of this document. Please be sure to download the desired version. For amendments, the text includes a list of changes, the rationale for the changes, and compatibility considerations. The following documents are listed by date, with the most recent first.

2025

Download A/342:2025-07 Part 2, “AC-4 System”, 17 July 2025. This version of the Standard is normatively referenced in A/300:2025-07.

2024

Download A/342:2024-04 Part 2, “AC-4 System”, 3 April 2024. This version of the Standard is normatively referenced in A/300:2024-04.

2023

Download A/342:2023-03 Part 2, “AC-4 System”, 28 March 2023. This version of the Standard is normatively referenced in A/300:2023-03.

2022

Download A/342:2022-03 Part 2, “AC-4 System”, 31 March 2022. This version of the Standard is normatively referenced in A/300:2022-04.

2021

Download A/342:2021 Part 2, “AC-4 System”, approved 10 March 2021. This version of the Standard is normatively referenced in A/300:2021.

2017

Download A/342:2017 Part 2, “AC-4 System”, approved 23 February 2017. This version of the Standard is normatively referenced in A/300:2019 and A/300:2020.