A/343, “Captions and Subtitles”Approved: 17 July 2025

This standard defines the required technology for closed caption and subtitle tracks over ROUTE-DASH and MMT transports. This includes the content essence and the packaging and timing.

Download current version: A/343:2025-07, “Captions and Subtitles”, 17 July 2025. This version of the Standard is normatively referenced in A/300:2025-07.

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/343:2018, “Captions and Subtitles”, approved 10 October 2018. This version of the Standard is normatively referenced in A/300:2019 and A/300:2020.

Download A/343:2018 Amendment No. 1, “Safe Area”, approved 8 February 2021.

Download A/343:2018 Amendment No. 2, “Font Names”, approved 20 September 2021.

Download A/343:2018, “Captions and Subtitles with Amendment No. 1”. This document has Amendment No. 1 integrated into the standard. This version of the Standard is normatively referenced in A/300:2021.

Download A/343:2018, “Captions and Subtitles with Amendments No. 1 and No. 2”. This document has Amendments No. 1 and No. 2 integrated into the standard.

Download A/343:2022-02, “Captions and Subtitles”, approved 10 February 2022.

Download A/343:2022-03, “Captions and Subtitles”, 31 March 2022. This version of the Standard is normatively referenced in A/300:2022-04.

Download A/343:2023-03, “Captions and Subtitles”, 28 March 2023. This version of the Standard is normatively referenced in A/300:2023-03.

Download A/343:2024-04, “Captions and Subtitles”, 3 April 2024. This version of the Standard is normatively referenced in A/300:2024-04.