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

Mission

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.

Code of Ethics and Professional Conduct

The W3C Code of Ethics and Professional Conduct applies to all TTWG work.

Discussion lists

Technical discussion takes place on GitHub repository issues and pull requests and 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.

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Wiki and Timed Text Resources

The TTWG also maintains the Timed Text wiki which includes a list of the TTWG's publications and a list of known implementations, resources and specifications.

Meetings

Meetings are held at 1600 UTC (winter time, where it applies) weekly on Thursdays, duration 1 hour. By exception 2 hour meetings may be scheduled, beginning at 1500 UTC. In summer time, meetings begin 1 hour earlier in UTC time.

Upcoming meetings are visible at the TTWG project dashboard.

Recent Activity and list of repositories

All of the TTWG's repositories can be found at Timed Text Working Group - Repositories page. Recent activity on the repositories where work is active at the moment can be found on the following repository links:

Group repositories

• TTWG business
• TTWG future requirements

Recommendation Track specification repositories

• IMSC
• IMSC Hypothetical Render Model (HRM)
• TTML1
• TTML2
• WebVTT
• Dubbing and Audio description Profiles of TTML2 (DAPT)
• TTML CJK Extension Module 1
• TTML CSS Extension Module (not currently actively being worked on)
• TTML Karaoke Extension Module
• TTML Live Extension Module (also includes WebSocket carriage mechanism and guide)
• TTML VR Extension Module (not currently actively being worked on)

Test repositories

• IMSC Tests
• IMSC Hypothetical Render Model (HRM) Tests
• Test contents for IMSC 1.0.1 Text
• Test contents for IMSC 1.1 Text
• Test contents for IMSC 1.1 Image
• TTML1 tests
• TTML2 tests
• WebVTT tests (on Web Platform Tests)

Working Group Notes, registries etc

• IMSC vNext Requirements
• PQ HDR in PNG
• TTML Profile Registry
• TTML to WebVTT mapping
• Requirements for the Dubbing and Audio description Profiles of TTML2 (DAPT)

Suspended Recommendation Track specification repositories

• TTML3
• ADPT

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:

• If you're affiliated with a W3C member organization
  1. Use the form for getting a W3C account
  2. Have your AC representative nominate you using the form for joining this Working Group.
• Subject to approval from the Working Group Chairs and Team Contacts, we also accept Invited Experts.

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