Web Media Text Tracks Community Group
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Web Media Text Tracks Communit...
Web Media Text Tracks Community Group
This group will work on text tracks for video on the Web, applied to captioning, subtitling and other purposes. This group plans to work initially on:
1) Documenting a semantic model underlying the caption formats in use, notably TTML, CEA 608/708, EBU STL, and WebVTT.
2) Creating a community specification for WebVTT.
3) Defining the mappings between WebVTT and some selected formats, including at least TTML (W3C/SMPTE), and CEA 608/708.
4) Creating web developer reference and tutorial material, including worked examples.
5) Creating a test suite and/or tools.
A possible transition to REC-track for some of these document(s) is envisaged and that possibility will be used to guide the work and procedures.
The group may produce recommendations for work in other groups, such as CSS, HTML5, and TTWG.
w3c/webvtt/
Group's public email, repo and wiki activity over time
Note: Community Groups are proposed and run by the community. Although W3C hosts these
conversations, the groups do not necessarily represent the views of the W3C Membership or staff.
Final reports /
licensing info
Date
Name
Commitments
2014-02-20
WebVTT
Licensing commitments
Drafts /
licensing info
Date
Name
2013-06-06
Conversion of 608/708 captions to WebVTT
Chairs, when logged in, may publish draft and final reports. Please see
report requirements
Implementation Status
Silvia Pfeiffer
Posted on:
February 22, 2015
I recently did a comparison of the implementation status of WebVTT features in the major browsers.
You can find it here:
WebVTT First Public Working Draft released
Silvia Pfeiffer
Posted on:
November 19, 2014
The Timed Text Working Group as per its
charter
has released the First Public Working Draft for WebVTT 1 at
This document will be following the new
publication process
As such, The TTWG will be working towards a Candidate Recommendation (CR) next.
Feedback on the spec is encouraged!
Web Platform Docs publishes good WebVTT Tutorial
Silvia Pfeiffer
Posted on:
April 27, 2014
Check out
to gain a good current overview of WebVTT and its use in browsers.
WebVTT 1.0 is part of the deliverables of the Timed Text WG
Silvia Pfeiffer
Posted on:
April 27, 2014
The
Timed Text WG charter
has been updated in March 2014. It includes delivery of a WebVTT 1.0 specification as a W3C Recommendation.
This means, a snapshot of the WebVTT specification has been taken,
FSA commitments
have been made, and the specification was submitted to the Timed Text WG as input to the standardization process. All features in this snapshot will now be tested across the different implementations, in particular across browsers. Those features that have been implemented interoperably will be taken to Recommendation over the next year.
This Community Group will continue to work on the WebVTT specification to address new features and collaborate with the Timed Text WG on any bugs found with the submitted specification.
Carriage of WebVTT and TTML in MP4 files
Cyril Concolato
Posted on:
September 11, 2013
As a result of the 105th MPEG meeting (see
Press Release
), MPEG has concluded its study of the carriage of Timed Text in the ISO Base Media File Format (MP4). The study resulted in draft standards for the carriage of WebVTT and TTML content that have reached Final Draft stage (FDAM 2 for 14996-12/15444-12 and FDIS for 14496-30). They are considered complete and are submitted to National Bodies for final vote. This post gives an overview of these draft documents.
MP4 basics and timed-text related specifications
An MP4 file is logically made of tracks. An MP4 track is a logical structure organized into samples and sample descriptions. Samples carry information that is valid from a given time and for a given a duration. Samples carry data that is continuous (no gap in time between samples) and non-overlapping (the end of a sample is the start of the next sample). This has good properties, and in particular allows random access into the track. A sample description carries information that is valid for the duration of several samples, typically for the whole track. This is an example of a
musica
track.
The amendment to Part 12 covers the basic syntax and semantics for a set of new text track types for a broad range of timed text formats. In particular, two track types have been defined: the ‘text’ type for track content that results in text rendering only; and the ‘subt’ type for track content that may result in text and graphics rendering.
Part 30 provides specific guidance for two popular timed text format technologies defined by W3C – Timed Text Markup Language (TTML) and Web Video Text Tracks (WebVTT) enabling use of those formats in context such as MPEG-DASH or HTML5 Media Source Extensions.
Continue reading
First Draft of Conversion of 608/708 captions to WebVTT published by Web Media Text Tracks Community Group
W3C Team
Posted on:
June 6, 2013
On 2013-06-06 the
Web Media Text Tracks Community Group
published the first draft of the following specification:
Conversion of 608/708 captions to WebVTT
Participants
contribute material to this specification under the
W3C Community Contributor License Agreement (CLA)
If you have any questions, please contact the group on their public list: public-texttracks@w3.org. Learn more about the
Web Media Text Tracks Community Group
WebVTT in Media Transport Formats
Silvia Pfeiffer
Posted on:
September 26, 2012
WebVTT is quite a powerful format. It has been developed to transport timed data chunks, including captions, subtitles, video descriptions, chapters, and in fact any chunk of data that cues up with a time segment of a media element.
The TextTrack API in HTML5 that provides the means to synchronize timed data chunks with media elements is specified generically such that these cues can come from a
US