ATSC Standards Update: Three Newly Approved Documents Published

Posted on October 21, 2025 in ATSC News

An update of A/331, “Signaling, Delivery, Synchronization, and Error Protection,” has been published on the ATSC web site. The document, A/331:2025-10, includes three amendment that were recently approved by the ATSC membership:

• A/331:2025-06 Amendment No. 1,“Time.” This document describes a set of changes to the treatment of “time” in A/300 and A/331 in order to alleviate any confusion between “GPS” (meaning the US GPS SATNAV system), whether providing time data or location data, and to clarify description of time generally.
• A/331:2025-06 Amendment No. 2, “User Agent String.” This document describes corrections to the User Agent string specification in Section 7.1.2.4 of A/331.
• A/331:2025-06 Amendment No. 3, “MPEG-H Audio.” This document describes changes to the Bit Stream Syntax for the Audio Stream Properties Descriptor and the accompanying semantics to accommodate use of a new MPEG-H 3D Audio profile specified in a recent amendment to the MPEG-H audio standard.

In addition, a new version of A/337, Application Event Delivery,” has been published as A/337:2025-10. This document includes an amendment approved by the membership within the past week to ensure that events can be handled the same way for both MMT and DASH linear services.

An updated Recommended Practice has been published that incorporates changes described in an amendment approved last week. A/339:2025-10, “Audio Watermark Modification and Erasure,” incorporates a set of changes that document the need for broadcasters to consider where in the redistribution path watermark modification and/or erasure is performed. This update describes potential downstream impacts based on where the watermark is modified and/or erased (i.e., upstream vs. downstream).

Additional membership ballots will be closing in the coming days.

Posted in ATSC News