TimedText
Timed Text Working Group
Overview
The Timed Text Working Group (TTWG) develops W3C Recommendations for online media captioning by developing and maintaining new versions and profiles of TTML (Timed Text Markup Language) and WebVTT (Web Video Text Tracks) based on implementation experience and interoperability feedback, and the creation of semantic mappings between those languages. The group also develops usage notes and manages registries to support implementors.
This is the Wiki for the activities associated with the updating of the Timed Text publications - see also the list of all TTWG publications.
Key documents:
The TTWG operates under the Latest Operative W3C Process for all documents currently on the Recommendation Track.
Publications
The group's publications are listed in detail on the Publications page.
Some important Documents
| Document | Status | Publication Date |
|---|---|---|
| TTML1 (Third Edition) | Recommendation | 08 November 2018 |
| TTML2 | Recommendation | 08 November 2018 |
| TTML2 (2nd Edition) | Candidate Rec Snapshot | 09 March 2021 |
| WebVTT | Candidate Rec | 04 April 2019 |
| IMSC1.2 | Recommendation | 04 August 2020 |
| IMSC1.1 | Recommendation | 08 November 2018 |
| IMSC1.0.1 | Recommendation | 24 April 2018 |
| DAPT | Working Draft | 14 November 2024 |
| Mapping Between TTML and WebVTT | Editor's Draft (Note) | n/a |
| TTML Media Type Definition and Profile Registry | Working Group Note | 19 November 2020. |
| TTML Role Registry | wiki | n/a. |
| Using the ITU BT.2100 PQ EOTF with the PNG Format | Editor's Draft (Note) | n/a |
The TTML specification allows users to define and use roles for elements, in order to manage this across disparate organisations (without resorting to using complex namespaced prefixes) a set of roles is recorded in the TTML role registry page.
Test Suites
- DAPT Test Suite. Consists of exemplar documents that either are valid DAPT documents or are not.
- IMSC Test Suite. Consists of IMSC documents and corresponding exemplar renders as PNG images and provides coverage for IMSC 1.0.1, IMSC 1.1 and IMSC 1.2 Text and Image profile documents.
- IMSC 1.0.1 Text Profile test content. Tests that reflects IMSC 1.0.1 Text Profile subtitles as used for production content.
- IMSC 1.1 Text Profile test content. Tests that reflect IMSC 1.1 Text Profile subtitles as used for production content, including exemplar SDR and HDR renders.
- IMSC 1.1 Image Profile test content. Tests that reflect IMSC 1.1 Image Profile subtitles as used for production content, including exemplar SDR and HDR renders.
- IMSC-HRM Test Suite. Consists of IMSC Text documents that just pass, or just fail, specific IMSC-HRM constraints.
- TTML1 Test Suite. Consists of validation and presentation tests that exercise normative requirements in TTML1.
- TTML2 Test Suite. Consists of validation and presentation tests that exercise normative requirements in TTML2.
Implementations and Specifications
See Timed Text Efforts and Specifications for a high-level list of TTML and WebVTT implementations. TTML1-3ED implementation report
See the IMSC1 implementation page for implementations and test cases for the IMSC1 specification. and IMSC1.0.1 Comments tracker.
TTWG Working Group F2F meetings
Other meetings
See the TTWG calendar.
Participants
TTWG members are listed at Participants.
Working methods
The TTWG currently operates different working methods for development of TTML2 and IMSC than for WebVTT.
TTML2 and IMSC and other documents are generally discussed in weekly telephone conferences. Work on all specifications tends to happen in github and on the reflector.
The TTWG no longer uses the old tracker - all issues are managed in the relevant GitHub repository for each product, where the TTWG repository is used to manage the home page and issues relating to the group as a whole, such as upcoming meetings.
Changes to products, including Change Proposals and New Features
All bugs, and feature requests must be recorded as issues which are managed on github in one of the group repositories. Specific change proposals are raised as pull requests in the appropriate repository, linked to the issues that they resolve.
Historic TTML change proposals are also listed in the Change Proposal Index
Issues and Pull Requests
For bugs it is sufficient simply to raise an issue on github following repos: imsc, ttml1, ttml2, ttml-webvtt-mapping and webvtt.
TTWG Dashboard issues/pull requests on github for following repos: imsc, ttml1, ttml2, ttml-webvtt-mapping and webvtt.
Mailing List
For queries, advice or suggestions relating to any TTWG specification, messages can be sent to the public email reflector which is archived here.
CSS
For examples of TTML styling (including IMSC and TTML2) that is currently difficult to map into CSS see TTML/CSSRequirements.
Actions
Individual actions are tracked using GitHub issues in the relevant repository, and assigned to the appropriate group member via their GitHub handle.
Mail archive
Emails to the group's public email address can be viewed in the public archive. Members can view emails to the group's member-only address in the member archive.
Evidence of Wide Review
- Guidelines and page detailing WebVTT Wide Review
- Guidelines and disposition steps and labels for TTM2 Wide Review
TTML Documentation
You can help by providing Timed Text Documentation.