Media Fragments Working Group Charter

The mission of the Media Fragments Working Group, part of the Video in the Web Activity, is to address temporal and spatial media fragments in the Web using Uniform Resource Identifiers (URI).

Join the Media Fragments Working Group.

End date 31 January 2011
Confidentiality Proceedings are public
Initial Chairs Erik Mannens, Raphaël Troncy
Initial Team Contact
(FTE %: 30)
Yves Lafon
Usual Meeting Schedule Teleconferences: Weekly
Face-to-face: 3-4 per year


This group is chartered to provide URI-based mechanisms for uniquely identifying temporal and spatial fragments for media objects in the Web, such as video, audio, and images. The Group will investigate the several possibilities in the URI syntax, such as URI fragment identifier or query parameters, to address a region of a media object and the impact at the application level.

In order to make video a first-class object on the World Wide Web, one should be able to identify temporal and spatial regions. Having global identifiers for arbitrary media segments/fragments would allow substantial benefits, including in linking, bookmarking, caching and indexing. For example, one should be able to point to the 20th second of the video news report, bringing you directly to a specific news item within the report. Another example is the ability to identify individuals or objects that are featured in the video. None of the existing solutions (such as MPEG-21 or temporal URI) is fully satisfactory or provides a general unique resource identifier for video clips independently of the format in use. The report from the Video on the Web workshop contains a summary of the current situation but it is expected that the Group will analyze past attempts as well. In addition, such mechanisms are also applicable for audio objects (temporal dimension), and images (spatial dimension). In response, the Media Fragments Working Group will investigate the existing solutions and approaches, such as MPEG-21, SVG, SMIL, or temporal URI.

The Group will focus on developing a mechanism to uniquely identify a temporal fragment within an audio or video object, that is independent of the underlying audio or video codec in use, and will also investigate the delivery of the requested resource to allow full or partial media retrieval using at least the HTTP protocol. Furthermore, the Group will provide the partial mapping between the developed URI syntax and the various ways of defining in XML or URI a temporal or a spatial region in W3C Recommendations such as SVG and SMIL.

The Group may hold Workshops, Interoperability Meetings, and other events as required to fulfill its mission.

Success Criteria

Out of Scope

This Working Group is not chartered to provide indirect mechanisms for temporal and spatial fragments, such as using XML descriptions. It will, however, recommend a mapping between the mechanisms existing in SVG and SMIL, and the developed URI syntax.


The Deliverables are divided in two phases, to allow rapid deployment of temporal and simple spatial media fragment URIs. Note that work on the second phase will depend on the success of the first Recommendation and will necessitate Director's approval for the charter extension for its completion.

The first phase will include:

  • A W3C Working Group Note for use cases and requirements for constructing temporal media fragment URIs for audio and video content, and simple spatial media fragment URIs for still images.
  • A W3C Recommendation for constructing simple spatial and temporal media fragment URIs (Media Fragments 1.0). This would also include delivery considerations.

The second phase will include:

  • A W3C Working Group Note for use cases and requirements for constructing spatio-temporal media fragment URIs for video content (including complex spatial regions for still images).
  • A W3C Recommendation for constructing spatio-temporal media fragment URI (Media Fragments 2.0)

Other Deliverables

  • Comprehensive implementation test suite for the specification.
  • Implementation and interoperability reports.
  • Analysis of existing solutions and approaches and their shortcomings
  • Analysis of constraints for creating a spatio-temporal URI specification on top of the existing URI standard (http://www.ietf.org/rfc/rfc3986.txt), e.g. fragment and query addressing, media types, protocol schemes, and URI templates
  • Tutorial or primer resources (if suitable and if resources are available).
  • Mapping of the identifier mechanism to and from SMIL, SVG and HTML media objects.
  • Propose a new charter for follow on work on spatial and temporal media fragments.


In the interest of producing of delivering the easiest and most achievable work within a small timeline, the Group will focus at producing the first phase first. Depending on the success of the Group, the charter will need to get extended in order to complete the second phase.

Note: See changes from this initial schedule on the group home page.

Note: The group will document significant changes from this initial schedule on the group home page.
Specification FPWD LC CR PR Rec
Use cases and requirements for Media Fragments 1.0 November 2008 December 2008
Media Fragments 1.0 February 2009 June 2009 September 2009 November 2009 January 2010
Use cases and requirements for Media Fragments 2.0 November 2009 January 2010
Media Fragments 2.0 November 2009 March 2010 July 2010 November 2010 January 2011

Note: The Use Cases and Requirements will evolve in phases to follow the phases of the Recommendation.

Timeline View Summary

  • August 2008: First teleconference
  • October 2008: First face-to-face meeting
  • November 2008: FPWD Use Cases and Requirements (Phase 1)
  • December 2008: LC for Use Cases and Requirements (Phase 1)
  • January 2009: Second face-to-face meeting
  • February 2009: FPWD for Media Fragments 1.0
  • March 2009: Third face-to-face meeting
  • June 2009: LC for Media Fragments 1.0
  • September 2009: CR for Media Fragments 1.0
  • November 2009: FPWD Use Cases and Requirements (Phase 2) and Media Fragments 2.0, and PR for Media Fragments 1.0
  • January 2010: REC for Media Fragments 1.0 and LC for Use Cases and Requirements (Phase 2)
  • January 2010: LC for Media Fragments 2.0
  • March 2010: Third face-to-face meeting
  • July 2010: CR for Media Fragments 2.0
  • November 2010: PR for Media Fragments 2.0
  • January 2011: REC for Media Fragments 2.0

Dependencies and Liaisons

As part of the Video in the Web Activity, the Media Fragment Working Group will be represented in the Hypertext Coordination Group.

Dependencies with W3C Groups

Synchronized Multimedia (SYMM) Working Group
The Synchronized Multimedia Integration Language (SMIL) allows authors to describe the temporal behavior of a multimedia presentation, associate hyperlinks with media objects and describe the layout of the presentation on a screen.
Scalable Vector Graphics (SVG) Working Group
The Scalable Vector Graphics language allows authors to describe two-dimensional vector and mixed vector/raster graphics. It includes support for multimedia: audio, video and animation.
HTML Working Group
The HTML 5 specification is intended to provide a semantic-level markup language and associated semantic-level scripting APIs for authoring accessible pages on the Web ranging from static documents to dynamic applications. It includes media elements to present audio data, or video and audio data.
Protocols and Formats Working Group
The PFWG looks at the formal Web technologies (protocols, formats, etc.) from an accessibility perspective.

Liaisons with W3C Groups

Protocols and Formats Working Group
The PFWG looks at the formal Web technologies (protocols, formats, etc.) from an accessibility perspective.
Hypertext Coordination Group
The purpose of this group is to identify technical areas where different working groups may overlap, encourage discussion, and to coordinate their work.
Technical Architecture Group (TAG)
W3C has created the TAG to document and build consensus around principles of Web architecture. This Group published several materials related to URIs, such as Usage Patterns For Client-Side URL parameters.
uri@w3.org mailing list
While the URI Activity has been closed, this mailing list remains in effect and should be kept in the loop.
public-sweo-ig@w3.org mailing list
While the Semantic Web Education and Outreach (SWEO) Interest Group has been closed this mailing list remains in effect and should be kept in the loop. The Cool URIs for the Semantic Web is one of the Interest Group Notes produced by the SWEO Group.

External Groups

Internet Engineering Task Force (IETF)
The IETF is a large open international community of network designers, operators, vendors, and researchers concerned with the evolution of the Internet architecture and the smooth operation of the Internet. This organisation is responsible for RFC 3986 (URI), RFC 3987 (IRI), RFC 2326 (RTSP), RFC 2912 (Media Features for MIME Content), and for discussion around video, audio, and image media types.
ISO/IEC JTC-1/SC-29 WG 11 Moving Picture Experts Group (MPEG)
This group is developing standards for coded representation of digital audio and video, including MPEG-4 and MPEG-21.
The Society of Motion Picture and Television Engineers (SMPTE)
This organization was founded to advance theory and development in the motion imaging field. Among others, it produced the "SMPTE STANDARD for Television, Audio and Film - Time and Control Code" (SMPTE 12M).
The Internet Captioning Forum (ICF)
This organization addresses the technical challenges presented by online video repurposed from broadcast or other previously captioned sources, as well as video created specifically for the Web.


To be successful, the Media Fragments Working Group is expected to have 7 or more active participants for its duration. Effective participation to the Media Fragments Working Group is expected to consume one work day per week for each participant until Last Call; two days per week for editors. The Media Fragments Working Group will allocate also the necessary resources for building Test Suites for each specification.

Participants are reminded of the Good Standing requirements of the W3C Process.


This group primarily conducts its work on the public mailing list public-media-fragment@w3.org.

Information about the group (deliverables, participants, face-to-face meetings, teleconferences, etc.) is available from the Media Fragments Working Group home page.

Decision Policy

As explained in the Process Document (section 3.3), this group will seek to make decisions when there is consensus. When the Chair puts a question and observes dissent, after due consideration of different opinions, the Chair should record a decision (possibly after a formal vote) and any objections, and move on.

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.

About this Charter

This charter for the Media Fragments Working Group has been created according to section 6.2 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.

Change notes:

Philippe Le Hégaret, plh@w3.org

$Date: 2012/06/12 09:34:06 $