[PROPOSED] Timed Media Working Group Charter

The mission of the Timed Media Working Group is to further develop timed media capabilities in the Open Web Platform, including but not limited to video and audio features.

The Timed Media Working Group will expand upon the basic capabilities provided by HTML5's <audio> and <video> media elements as well as develop lower level APIs that provide the foundation for features developed by the Audio Working Group, the WebRTC Working Group, and others.

Join the Timed Media Working Group.

Start date@@
End date30 September 2017
ConfidentialityProceedings are public
Initial ChairsCHAIR INFO
Initial Team Contacts
(FTE %: 70)
Yosuke Funahashi, TBD
Usual Meeting Schedule Teleconferences: weekly coordination calls will be held, with additional calls as needed.
Face-to-face: we will meet during the W3C's annual Technical Plenary week; additional face-to-face meetings may be scheduled by consent of the participants.


The Web is increasingly used to share and consume timed media (including video and audio). The Timed Media Working Group will work on specifications for enhancing these experiences through new mark-up and APIs. Several other working groups (such as the Audio Working Group and the Web Real-Time Communications Working Group) are building sophisticated capabilities that need a common basic set of "bedrock" APIs. The Timed Media Working Group will coordinate the requirements from these and other groups and produce specifications to address these needs.


The scope of the Timed Media Working Group covers technologies related to the capture, acquisition, orchestration and playback of timed media such as video and audio. The Timed Media Working Group deliverables must address issues of accessibility, device independence, interoperability, mobility, privacy, and security. The Working Group should address the Media Accessibility User Requirements, and features that aid accessibility such as captions and transcripts are in scope. Functionality to coordinate other interactions with timed events in the media files is in scope.

Success Criteria

In order to advance beyond Candidate Recommendation, each specification is expected to have at least:

Out of Scope

The group will not work on developing codecs, new media formats, security protocols, or new encryption algorithms.

The group will not work on audio processing APIs or real-time communication but will liaise with the Audio Working Group and the Web Real-Time Communications Working Group to ensure lower level capabilities created by the Timed Media Working Group are compatible with those groups' goals.


Recommendation-Track Deliverables

The working group will deliver the following W3C Recommendations:

Media Source Extensions
A specification that extends HTMLMediaElement to allow JavaScript to generate media streams for playback. Allowing JavaScript to generate streams facilitates a variety of use cases like adaptive streaming and time shifting live streams.
Encrypted Media Extensions
This specification extends HTMLMediaElement providing APIs to control playback of protected content. The API supports use cases ranging from simple clear key decryption to high value video (given an appropriate user agent implementation). License/key exchange is controlled by the application, facilitating the development of robust playback applications supporting a range of content decryption and protection technologies.
Low Level Audio and Video support
The Timed Media Working Group will work on low-level media APIs to support the work of the Audio and Web Real-Time Communications Working Groups.

Specification Maintenance

The Timed Media Working Group will maintain errata and new editions, as necessary, for the HTMLMediaElement related sections of HTML 5.0 (e.g. sections 4.7.6 to 4.7.10). When future versions of HTML are published as modules, the working group will deliver future versions of these timed media features as a W3C Recommendation.

Other Deliverables

The Timed Media Working Group may produce specifications for the following features:

If the current Transcript proposal gains implementation support and momentum, this Group will adopt the proposal.
Captioning support
The group may produce a specification to enhance the timed text and caption API support available to HTML5 media elements.
Inband Track Support
If the Media Resource In-band Tracks Community Group produces a mature specification with implementation support then the Timed Media Working Group may adopt this work onto the Recommendation Track.
Media Capture
The WebRTC and Device APIs Working Groups have been collaborating in the Media Capture Task force on the development of specifications that enable the capture and processing of media streams. Upon the request of these groups, the Timed Media Working Group may adopt the further development and maintenance of these specifications.
If the Multi-Device Timing Community Group produces a mature specification with implementation support, then the Timed Media Working Group may adopt this work onto the Recommendation Track.

The Working Group may use the Web Platform Community Group or other Community Groups to explore possible new work within its scope that is not covered in the deliverables above. If the Working Group decides to add new features or specifications to its deliverables, it will recharter with changes to that new charter limited to just changes in deliverables.


Note: The group will document significant changes from this initial schedule on the group home page.
Specification FPWD LC / CR PR Rec
Media Source Extensions (MSE) - - Q4 2015 Q1 2016
Encrypted Media Extensions (EME) - Q4 2015 Q1 2016 Q2 2016

The transcript proposal is expected to reach FPWD in October 2015.

Dependencies and Liaisons

W3C Groups

Web Platform Working Group
This group continues the development of the HTML language, provides specifications that enable improved client-side application development on the Web, including application programming interfaces (APIs) for client-side development and markup vocabularies for describing and controlling client-side application behavior.
Audio Working Group
This group creates API specifications for audio processing and is interested in low level audio device APIs.
Device APIs Working Group
To coordinate regarding APIs for devices services.
Timed Text Working Group
This group creates specifications for media online captioning including Timed Text Markup Language (TTML) and WebVTT (Web Video Text Tracks).
Media Resource In-band Tracks Community Group
This group is developing a specification for exposing in-band tracks to HTML5 media elements.
Multi-Device Timing Community Group
This group is developing a specification for exposing a common, multi-device, timing mechanism.
Web and TV Interest Group
This group may provide advice about scenarios and requirements for the specifications.
Web Real-Time Communications Working Group
This group creates API specifications for real time media and is interested in low level audio/video device APIs.
Second Screen Presentation Working Group
This group creates API specifications for controlling secondary screens for displaying web content. The Timed Media Working Group may provide APIs to project media through a secondary screen.
Accessible Platform Architectures Working Group
To ensure that Timed Media WG deliverables appropriately support accessibility requirements, including those described in the Media Accessibility User Requirements.
Internationalization Core Working Group
This group may provide advice or review to ensure that Timed Media WG deliverables meet the needs of an international Web.
Privacy Interest Group
The Timed Media WG will request review of specifications and communicate as necessary with this group.
Web Applications Security Working Group
To ensure proper security for applications on the Web.


To be successful, the Timed Media Working Group is expected to have 10 or more active participants for its duration, and to have the participation of industry leaders in fields relevant to the specifications it produces.

The Chairs and specification Editors are expected to contribute one day per week towards the Working Group. There is no minimum requirement for other Participants. This Working Group will also allocate the necessary resources for building Test Suites for each specification.

The group also welcomes non-Members to contribute technical submissions for consideration, with the agreement from each participant to Royalty-Free licensing of those submissions under the W3C Patent Policy.


The Working Group conducts its work primarily through GitHub repositories, for contributions and communications. There will be one GitHub repository per document. Similar to open-source software development, peer production is encouraged: changes will be executed through Pull Requests, where each pull request gets preferably reviewed before being merged. Regular activity summaries around the GitHub repositories MUST be provided.

The Group may also use a mailing list. Subscription to these lists is open to the public, subject to W3C norms of behavior.

Decision Policy

As explained in the Process Document (section 3.3), this group will seek to make decisions when there is consensus. The expectation is that typically, an editor or other participant makes an initial proposal, which is then refined in discussion with members of the group and other reviewers, and consensus emerges with little formal voting being required. However, if a decision is necessary for timely progress, but consensus is not achieved after careful consideration of the range of views presented, the Chairs should put a question out for voting within the group (allowing for remote asynchronous participation -- using, for example, email and/or web-based survey techniques) and record a decision, along with any objections. The matter should then be considered resolved unless and until new information becomes available.

Any resolution taken in a face-to-face meeting or teleconference is to be considered provisional until 10 working days after the publication of the resolution in Call for Consensus sent to the working group's mailing list. If no objections are raised on the mailing list within that time, the resolution will be considered to have consensus as a resolution of the Working Group.

This charter is written in accordance with Section 3.4, Votes of the W3C Process Document and includes no voting procedures beyond what the Process Document requires.

Patent Policy

This Working Group operates under the W3C Patent Policy (5 February 2004 Version). To promote the widest adoption of Web standards, W3C seeks to issue Recommendations that can be implemented, according to this policy, on a Royalty-Free basis.

For more information about disclosure obligations for this group, please see the W3C Patent Policy Implementation.


This Working Group will use the W3C Software and Document license for all its deliverables.

About this Charter

This charter for the Timed Media Working Group has been created according to section 5 of the Process Document. In the event of a conflict between this document or the provisions of any charter and the W3C Process, the W3C Process shall take precedence.