Timed Text Working Group
Delivering Captioning and Video Description for the Web



The mission of the Timed Text Working Group is to develop W3C Recommendations for media online captioning by developing and maintaining new versions of the Timed Text Markup Language (TTML) and WebVTT (Web Video Text Tracks) based on implementation experience and interoperability feedback, and the creation of semantic mappings between those languages.

Emmy Award

The W3C TTWG was rewarded with a Technology & Engineering Emmy Award from the National Academy of Television Arts & Sciences (NATAS) for its Timed Text Mark-up Language (TTML1) in category "Standardization and Pioneering Development of Non-Live Broadband Captioning", on 08th January 2016 at the Bellagio in Las Vegas.

TTWG and Emmy Award
[left to right]: Glenn Adams (Skynav), Mike Dolan (SMPTE), Philippe Le Hégaret (W3C), Thierry Michel W3C).

Press Release and more pictures and video of the Emmy Award ceremony are available.

Timed text WG activities

Refer to the TTWG wiki to learn more about the TTWG Working group Efforts and Specifications, Documentations, Implementations experience, meetings and F2F meetings.

Introduction to Captioning Formats, TTML derivatives and WebVTT formats.

Timed Text Registry

TTML Media Type Definition and Profile Registry

Timed Text Publications

See the publication dashboard.

Timed Text Issues Tracker

see the TTWG Dashboard issues/pull requests from github

Test Suite

For TTML, we worked on a test suite:

For WebVTT, the test suite is part of web-platform-tests.

Discussion lists

Technical discussion takes place on the Working Group discussion list, public-tt@w3.org (archive). This is a public mailing list; to subscribe to the public-tt mailing list, please check the subscription procedure.

Search the archive help

How to join the group

This group operates under the W3C Patent Policy, which ensures that specifications published by the group can be implemented on a royalty-free (RF) basis. To record agreement from all participants with that W3C Patent Policy, joining the group involves completing several steps:

When you join, you will be added to public-tt, the publicly archived mailing-list for the group.