**DRAFT** Timed Text Working Group Charter

Scope

This group is chartered to develop formats used for the representation of text synchronized with other timed media, like audio and video. Such formats MUST be useable for online media captioning, should be useable for described video (aka video/audio description) and should address the media accessibility user requirements. Such formats MAY also be useable for broadcast production and exchange and MUST be useable in the context of HTML.

The Group will:

1. Publish a Recommendation for a new Timed Text Markup Language (TTML) 2 specification. In the process of producing this new revision, the Group WILL:
   1. Address any issues found during the development of a Simple Delivery Profile for Closed Captions.
   2. Consider for adoption features from existing formats, such as CEA608 or CEA708, or developed by groups such as SMPTE, DECE and EBU
   3. Produce other technical reports (Notes) on aspects of TTML processing as appropriate.
   4. Seek backward compatibility with TTML 1 whenever possible.
   5. Will provide a mapping with HTML5/CSS3, including describing TTML intermediate synchronic document as HTML5 document fragment, and understanding how the presentation syntax and semantics relate to CSS3.
   6. As required, produce a test suite for the above.
   7. Produce an implementation report, based on the test suite above.
2. Publish a Recommendation for the WebVTT language, in particular the parts that cover the syntax, semantics, and rendering of subtitles, delivery of metadata, captions, chapter markers, and textual audio descriptions for speech synthesis. The Group is expected to produce annual updates for the Recommendation with previously unspecified features from browser vendors.

   In the process of producing the specification, the Group WILL:

   1. Address any issues found in WebVTT: The Web Video Text Tracks Format produced by the Web Media Text Tracks Community Group. Some may be deferred to future versions.
   2. Include all features that have at least two independent and interoperable implementations
   3. Solidify the set of features through the creation of a WebVTT test suite
   4. Consider the adoption of new features
3. The group MAY decide to the use the experimental license, developed for HTML extensions, for the VTT document.
   Editororial Note: Why does this ask for permission to use the experimental license?

   The experimental license was approved only for products of the HTML working group. Though VTT is often thought of as an HTML extension (notably by the original author), this work will be going on in the more appropriate TTML working group, dedicated to Timed Text, and thus it doesn’t fall automatically into the approved category. The original version of the VTT document was developed in a Community Group, and CG deliverables have a fairly liberal license. The group is keen to avoid the problem that the CG output(s) become more used/referenced than the WG official documents, as a consequence of their more liberal license: in a sense, this would be encouraging the very forking that the W3C license normally tries to avoid. Ideally the CG output(s) are seen as, and marked as, and understood as, precursors to the WG output(s), and the WG Recommendation Track documents are seen as current and are the ones used, referenced, and so on. By using a liberal license for the WG document(s), we can avoid having the CG documents be apparently ‘more attractive’, and thus we can effectively retire them.

   (We note that this work is among the first to move from Community to Working group, and this issue may come up again.)

   If problems are found with this approach, the group will use the W3C document license, and try to handle the transition as gracefully as it can.

4. Establish a semantic mapping between TTML and WebVTT in order to facilitate browser implementation and market adoption.
5. Maintain a simple constrained profile for delivery of closed captions for video content ("Simple Delivery Profile for Closed Captions") for TTML.
6. Maintain TTML 1.
7. Publish a text and an image profile of the Timed Text Markup Language (TTML) appropriate for worldwide subtitling applications, including dialog language translation, content description, captions for deaf and hard of hearing, etc., using TTML Text and Image Profiles for Internet Media Subtitles and Captions as basis.
8. Produce a technical report (Note) on the application of TTML in live production and streaming such as for video content.
9. Produce a technical report (Note) on the conversion of CEA-608/708 data streams to WebVTT.

The new work is expected to be broadly available and should be provided on a timely fashion. This charter features a tightly constrained scope designed to ensure that the Working Group will meet its schedule and objectives.

Success Criteria

The Working Group is expected to demonstrate at least two interoperable implementations of all available features in the recommendations.