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.
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
- 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.
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
| Future | |
| TPAC 2024 in Anaheim, USA Friday 27 September 2024. | Agenda: w3c/ttwg#291 |
| Historic | |
| TPAC 2019 in Fukuoka, Japan 16-20 september 2019. | Minutes: day 1, day 2. |
| 31 January- 1st February 2019: F2F in Geneva Switzerland. | Minutes: day 1, day 2. |
| 22-23 October 2018 during TPAC18 in Lyon, France (TPAC18 overview) | Minutes: day 1, day 2 . |
| 9-10 January 2018 in Cupertino, CA | Minutes: day 1, day 2. |
| 9-10 November 2017 during TPAC17 in Burlingame, CA | Minutes: both days. |
| 12-13 January 2017 at BBC in London , UK | Minutes: day 1, day 2. |
| 19-20 September 2016 TPAC in Lisbon, Portugal | Minutes: day 1, Joint meeting with Web & TV IG, day 2 |
| 26-30 oct TPAC 2015 in Sapporo, Japan | Minutes: day 1, day 2. |
| 9-10 April 2015 in the US , Las Vegas | Minutes: day 1, day 2. |
| 2014 Oct (TPAC) F2F in Santa Clara USA | Minutes: both days. |
| 2014 Sep F2F in Geneva Switzerland | Minutes: day 1, day 2. |
| 2013 Nov (TPAC) F2F in Shenzen China | Minutes: day 1, day 2. |
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 WebVTT tends to happen in github and on the reflector.
Those products that are managed with tracker are listed at products. Users of these products may identify issues within them, either before or after publication, and may wish to contribute developments, ideas or editorial changes to a product prior to publication.
Changes to products
All proposed changes must be recorded as issues which are managed on github following repos: imsc, imsc-tests, PQ HDR in PNG, ttml1, ttml2, ttml-webvtt-mapping and webvtt.
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.
Issues that need further elaboration can be documented and discussed by adding a page link here.
- Issue 151 Clarify syncbase in SMPTE continuous mode
New features
For development of new TTML features it is preferred that the features are described within #Change Proposals and discussed prior to approval either by teleconference meetings, usually held weekly, at face to face meetings, held on an occasional basis, or on the public email reflector which is archived here. The Chair approves change proposals according to the W3C consensus policy.
CSS
For examples of TTML styling (including IMSC and TTML2) that is currently difficult to map into CSS see TTML/CSSRequirements.
Actions
Where actions are assigned to members in order to progress an issue or a change proposal these are recorded in the tracker.
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.
Change Proposals
As we look to creating the next version of the specification to address open issues we will adopt a lightweight change proposal mechanism. These change proposals are recorded in the Change Proposal Index
Evidence of Wide Review
- Guidelines and page detailing WebVTT Wide Review
- Guidelines and disposition steps and labels for TTM2 Wide Review
TTML Action Items
Action items are tracked.
TTML Documentation
You can help by providing Timed Text Documentation.