A/331, “Signaling, Delivery, Synchronization, and Error Protection”Approved: 3 April 2024

This document specifies protocols used for delivery and synchronization of media and non-timed data in the ATSC 3.0 system. A/331 specifies the technical mechanisms and procedures pertaining to service signaling and IP-based delivery of a variety of ATSC 3.0 services and contents to ATSC 3.0-capable receivers over broadcast, broadband, and hybrid broadcast/broadband networks. The service signaling functionality defines the data formats and information components necessary to discover and acquire user services. The IP-based delivery functionality specifies two application transport protocols for the carriage of media content and service signaling data over broadcast and/or broadband networks to receivers. The delivery functionality also includes mechanisms for the synchronization of media components delivered on the same or different transport networks, and application-layer forward error correction methods that enable error-free reception and consumption of media streams or discrete file objects. A component of this standard is the accompanying schema.

Download current version: A/331:2024-04, “Signaling, Delivery, Synchronization, and Error Protection”, 3 April 2024, and accompanying schema. This version of the Standard is normatively referenced in A/300:2024-04.

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.

Download A/331:2019, “Signaling, Delivery, Synchronization, and Error Protection”, and accompanying schema, approved 20 June 2019. This version of the Standard is normatively referenced in A/300:2019.

Download A/331:2019 Amendment No. 1, “MMT Hybrid Delivery”, approved 6 January 2020.

Download A/331:2019 Amendment No. 2, “Fix Daylight Saving”, approved 16 January 2020.

Download A/331:2019 Amendment No. 3, “ServiceId URL and BSID-PLP Mapping”, approved 26 December 2019.

Download A/331:2019 Amendment No. 4, “User Agent String”, approved 15 January 2020.

Download A/331:2019 Amendment No. 5, “Fix RRT”, approved 30 December 2019.

Download A/331:2019 Amendment No. 6, “Simulcast TSID”, approved 31 December 2019.

Download A/331:2019 Amendment No. 7, “DRM System ID”, approved 3 January 2020.

Download A/331:2019 Amendment No. 8, “Uniqueness of @serviceID”, approved 1 January 2020.

Download A/331:2019 Amendment No. 9, “Fix Keep Screen Clear”, approved 2 January 2020.

Download A/331:2020, “Signaling, Delivery, Synchronization, and Error Protection”, 16 January 2020. This document is a rollup of Amendments No. 1 through 9 to A/331:2019. The accompanying schema (unchanged from A/331:2019) can be downloaded from the above link. This version of the Standard is normatively referenced in A/300:2020.

Download A/331:2020 Amendment No. 1, “Multiple App Fixes”, approved 27 October 2020. See also the accompanying schema.

Download A/331:2020 Amendment No. 2, “AEAT Subgroups”, approved 19 January 2021. See also the accompanying schema.

Download A/331:2021, “Signaling, Delivery, Synchronization, and Error Protection”, 19 January 2021, and accompanying schema. This document is a rollup of A/331:2020 with Amendments No. 1 and 2.

Download A/331:2021 Amendment No. 1, “RRT Schema”, and accompanying schema, approved 22 April 2021.

Download A/331:2021 Amendment No. 2, “Advanced Emergency Information”, and accompanying schema, approved 27 May 2021.

Download A/331:2021 Amendment No. 3, “HELD Processing Order”, approved 8 June 2021.

Download A/331:2021 Amendment No. 4, “User Agent”, approved 1 October 2021.

Download A/331:2021, “Signaling, Delivery, Synchronization, and Error Protection, with Amendments No. 1, 2, and 3”. This document has Amendments No. 1, 2, and 3 integrated into the standard. An administrative rollup of the schemas for A/331:2021 with Amendments No. 1, 2, and 3 is also available: download the ZIP file. This version of the Standard is normatively referenced in A/300:2021.

Download A/331:2021, “Signaling, Delivery, Synchronization, and Error Protection, with Amendments No. 1, 2, 3, and 4”. This document has Amendments No. 1, 2, 3, and 4 integrated into the standard. An administrative rollup of the schemas for A/331:2021 with Amendments is also available: download the ZIP file.

Download A/331:2021 Amendment No. 5, “Broadcast-Broadband Configuration Signaling”, approved 9 November 2021.

Download A/331:2022-02, “Signaling, Delivery, Synchronization, and Error Protection”, and accompanying schema, approved 15 February 2022.

Download A/331:2022-03, “Signaling, Delivery, Synchronization, and Error Protection”, and accompanying schema, 31 March 2022. This version of the Standard is normatively referenced in A/300:2022-04.

Download A/331:2022-03 Corrigendum No. 1, “SLT and S-TSID”, approved 22 September 2022.

Download A/331:2022-09, “Signaling, Delivery, Synchronization, and Error Protection”, and accompanying schema, 22 September 2022.

Download A/331:2022-09 Amendment No. 1, “Signaling Server”, approved 30 November 2022.

Download A/331:2022-11, “Signaling, Delivery, Synchronization, and Error Protection”, and accompanying schema, 30 November 2022.

Download A/331:2022-11 Amendment No. 1, “Application Lifecycle”, approved 8 February 2023.

Download A/331:2022-11 Amendment No. 2, “Timing/Buffer Model – IMSC1”, approved 16 February 2023.

Download A/331:2023-02, “Signaling, Delivery, Synchronization, and Error Protection”, and accompanying schema, 23 March 2023.

Download A/331:2023-03, “Signaling, Delivery, Synchronization, and Error Protection”, and accompanying schema, 28 March 2023. This version of the Standard is normatively referenced in A/300:2023-03.

Download A/331:2023-03 Amendment No. 1, “MMT DRM”, approved 16 August 2023.

Download A/331:2023-08, “Signaling, Delivery, Synchronization, and Error Protection”, 16 August 2023, and accompanying schema.

Download A/331:2023-08 Amendment No. 1, “FDT Enhancement”, and accompanying schema, approved 4 October 2023.

Download A/331:2023-10, “Signaling, Delivery, Synchronization, and Error Protection”, 4 October 2023, and accompanying schema. Schema relating to A/331:2023-08 Amendment No. 1 (see above) may be downloaded from this link.

Download A/331:2023-10 Amendment No. 1, “MMT Signing”, approved 13 December 2023.

Download A/331:2023-12, “Signaling, Delivery, Synchronization, and Error Protection”, 13 December 2023, and accompanying schema. Schema relating to A/331:2023-08 Amendment No. 1 (see above) may be downloaded from this link.