"Television and the Web" Interest Group Charter
This charter is written in accordance with
section 3.2.2 of the
W3C Process.
Table of Contents
W3C held a Workshop
on "Television and the Web" (TVWeb) in June 1998. At this workshop, it
became evident that different standardization bodies and vendors will make
a significant effort over the next year to integrate Web and television
technologies. This enables applications such as browsing the Web using a
television set, or using Web content formats to annotate a television broadcast,
making the television more interactive.
Historically, television standards tend to differ between regions of the
world, and are issued by regional standardization bodies. Thus, a television
receiver purchased in one part of the world is not necessarily usable in
another part of the world. This is in stark contrast with the technology
used by the Word Wide Web. Any Web user can read all Web pages, no matter
where in the world they are stored, because the Web uses the same technology
all over the world. The integration of TV and the Web should not lead to
a fragmentation of the Web, even though such fragmentation is typical in
the television world.
The World Wide Web Consortium is an international organisation, with branches
in America, Asia and Europe. It is therefore well-positioned to avoid the
regional solutions typical of TV standards when it comes to integrating the
Web and television.
The participants at the "TVWeb" workshop expressed interest in W3C taking
a more active role in the ongoing efforts of TV/Web integration, particularly
since these efforts concern subsetting or extending some of the core W3C
technologies (HTML, CSS, XML, ...).
This Interest Group has three missions:
-
It serves as a pool of experts on TV/Web integration, some of which will
participate in the W3C working groups relevant to TV/Web integration.
-
It serves as a coordination body with the TV-specific regional standardization
groups working on TV/Web integration.
-
It will prepare and review documents related to TV/Web integration.
These documents should be produced quickly (typically within two months).
Their purpose is mainly to point out specific requirements in the area of
TV/Web integration, and to give rough ideas on how these requirements can
be resolved.
It is not the main purpose of this Interest Group (or any
W3C Interest Group, for that matter) to produce specifications. Production
of specifications and W3C recommendations is reserved to W3C working groups
(see definition of
interest group
in W3C process).
Scope and Deliverables
The W3C process defines
the general scope of an
interest group as
follows:
"An Interest Group brings together people who wish to evaluate potential
Web technologies and policies. An Interest Group does not have the goals
of a Working Group -- development of specifications or code. Instead, it
serves as a forum to explore cooperation and exchange ideas.
It is quite possible that an Interest Group's studies will lead to the creation
of a Working Group, but this may not be known in advance nor is it guaranteed."
The following list of topics and deliverables is based on discussions at
the W3C workshop
on "Television and the Web". Additional topics may be added during the
lifetime of the Interest Group, if there is enough interest.
Deliverables that are documents must fulfil the following conditions:
-
One or more authors are assigned to the document.
-
Before work can be started, the document must be assigned a date at which
it will be declared stable. Any remaining issues at this date will be described
in the document, and not delay of making the document stable.
A first important mission of the TVWeb IG is to coordinate with efforts in
other TV standardization groups, avoiding duplication of effort and fragmentation
of the Web by incompatible standards.
To fulfill its goal as a forum for coordination and exchange between TV
standardization bodies and W3C, the TV IG should produce and maintain a list
of contact persons to relevant organisations, e.g. the ones listed in the
section "external groups". A contact person
will inform the IG (or the IG chair, if confidentiality requires this) of
relevant event in the group she is responsible for, such as the publication
of a new Web-related specification, a Web-related meeting etc. The contact
person will also inform the external group about relevant W3C events, if
W3C's confidentiality requirements allow this.
In the television community, there is a desire to adapt certain W3C
specifications before using them in TVWeb applications. This means that only
a limited set of features of these specifications may be supported, or that
new, TV-specific features are added to these specifications. This requires
that some members of the Interest Group represent TV-specific interests in
the HTML- and CSS working groups.
These additions may take the form of a specialised tagset within the framework
set by the W3C working group on HTML.
Conditions:
-
Minimal Membership Commitment: Two authors for the document must sign
up.
-
Minimal Membership Commitment: At least one member employee must sign
up as representative to the HTML WG.
Conditions:
-
Minimal Membership Commitment: Two authors for the document must sign
up.
-
Minimal Membership Commitment: At least one member employee must sign
up as representative to the CSS WG.
A new URL scheme is needed to address content that is broadcast in a TV channel.
This requires to study and, potentially, harmonize existing proposals for
tv-related URLs, such as the following:
The review must take the results
URL registration
Working Group in the IETF of the into
account. The idea is to review the existing approaches within the W3C TV
IG, after which they will be proposed to the IETF, in order to become
standards-tracks RFCs, similar to other URL schemes
(mailto:,
...).
Conditions:
-
For the W3C TV IG to take on this issue, the organisations or authors currently
of tv-related URL specifications must make at least a request that they should
be reviewed by the W3C, and preferably submit them as documents.
-
Minimal Membership Commitment: Two authors for the document must sign
up.
The following work items have been suggested at the
W3C workshop on
"Television and the Web". It depends on whether there is sufficient interest
and commitment within the group to pursue them:
-
Authoring guidelines
-
These authoring guidelines should describe in layman-terms how to use HTML
and CSS so that you can do "author-once - display anywhere", instead of having
to redevelop every site several times for different display environments.
-
Default style sheet for TV
-
A television set has different display characteristics than an PC. Consequently,
the default presentation rules for HTML on PCs cannot be transformed without
modification into the TV world. But TVs can also benefit from the existence
of a well-defined default style sheet. This requires analysing existing products,
and distilling common rules used in these products for displaying HTML on
a TV screen. The result should be a document produced by the TV IG, documenting
existing practice and recommending (but not necessarily standardizing) empirical
default settings to implementors of new products. A
first draft of
a default style sheet is already available.
-
Metadata description/transport
-
There is an opportunity to harmonize work in the television community on
MPEG-7
with W3C's RDF work. This required submitting RDF to a call for proposals
by RDF.
-
Interaction mechanisms for continuous media
-
This concerns issues such as starting/stopping/fast forwarding an video/audio
stream, but also "interesting linking behavior". The TV IG should come up
with an initial draft that is then passed to a Working Group in the DOM activity.
-
Device profiles
-
To avoid that the set-top box tries to display content with features that
it does not support, a mechanism for describing device profiles is needed.
This should be coordinated with the techniques used by the
Mobile IG , and take into
account the results of the IETF
Working Group
on Content Negotiation
-
Guidelines for re-processing color palettes
-
Guidelines on how to translate between different color palettes of different
devices will help content authors to know what color transformations will
take place.
-
Transition effects in CSS
-
CSS appears to be the right vehicle to express an enumerated set of transition
effects, as it is concerned with presentation. Another possibility is expressing
transition effects in SMIL, since this language takes into account temporal
aspects. The TV IG should come up with a document listing a set of "standard"
transition effects, and communicate it to the CSS working group and the former
SMIL working group.
-
Accurate layout control/Accurate Timing Control
-
Accurate layout and timing control are important issues when integrating
Web content with television content. The interest group should clarify in
how far the existing mechanisms in the W3C recommendations CSS and SMIL are
insufficient to achieve these goals. If missing functionality is identified,
it should be integrated into future versions of these W3C recommendations.
-
API to VCR controls (and other devices)
-
A Web page can provide functionality to control devices such as a VCR used
to register a television program. This requires a standardized API.
-
Flexible temporal synchronization using CSS
-
Expressing temporal synchronization in CSS allows reuse of certain kinds
of Web content. This effort should be aligned with the SMIL approach to
synchronization. Properties should be added to CSS that allow expressing
temporal aspects of presenting information. These properties should be aligned
with the SMIL attributes and time model.
-
Unidirectional HTTP
-
Unidirectional HTTP as proposed by the Advanced Television Enhancement Forum
(ATVEF) mainly defines a subset of headers
used in http responses that should be transmitted together with the web-content
in the television signal.
This Interest Group is scheduled for one year, from end of September 1998
to end of September 1999.
The Interest Group has fulfilled its mission if it succeeds in unifying the
efforts of different TV standardization bodies for Web integration, and in
avoiding a fragmentation of the Web.
By defaults, all documents developed by the IG are public.
Documents have a date at which they will be declared stable. Any remaining
issues at this date will be described in the document, and not delay of making
the document stable.
Documents that are prepared as deliverables of the Interest Group will be
published on the W3C site.
Documents that do not fulfill the criterion above (e.g. longer documents
describing specific technical solutions brought up by one member of the IG)
have to be submitted to W3C before they can be published on the W3C site.
Milestones are only set for the first months of this Interest Group. Additional
milestones may be added when the group decides to take on additional work
items.
-
20 August, 1998:
-
Interest Group Proposal/Call for Participation
-
17 September, 1998:
-
Deadline to submit AC Votes on Proposal
-
6 October, 1998:
-
Director's Decision
-
Start work on tv-URL scheme
Start work on document on TV-specific requirements to HTML
Start work on document on TV-specific requirements to CSS
-
13 October, 1998
-
Appoint representative(s) of TV IG to HTML WG
Appoint representative(s) of TV IG to CSS WG
Publish first list of contact persons to external groups
-
10 November, 1998
-
First stable document of TV-specific requirements to CSS
First stable document of TV-specific requirements to HTML
-
30 November, 1998
-
Submit stable document on tv-URL scheme to IETF (for
December IETF meeting
(Dec 7 - 11))
-
Pre-register RDF in MPEG-7 "Call for Proposals" (deadline: 1 December)
-
15 January
-
Submit RDF as response to MPEG-7 "Call for Proposals" (deadline: 1 February)
-
30 September, 1999:
-
Interest Group Completion
To facilitate cooperation with the TV community, this charter and the
archives of the Group's
mailing list (www-tv@w3.org) will be open to the public.
The TVWeb IG will have to into account technologies developed by other groups
within W3C, and to advise them about the requirements of television. As of
today, the following ongoing W3C activities are concerned:
-
CSS
& FP WG,
XSL
WG: Style sheets are a very
important means to achieve reusability of Web content on different display
devices. The limited memory size of settop boxes may require subsetting CSS.
Display on television sets may require adding new properties to CSS, such
as properties for transition effects, temporal layout and accurate layout
control
-
DOM WG: Work on an API for
controlling audio/video streams, and for controlling VCRs and other
devices may be pursued within a DOM-related WG.
-
Future
HTML
WG: The display of Web content
on television receivers may result in new requirements for the work on a
future version of HTML. The limited memory size of TV settop boxes may lead
to the need of HTML subsets. The future HTML WG is chartered to develop a
modularized version of HTML, which should be usable to express a TV-specific
subset. Furthermore, display on television may incur the need for new HTML
elements, e.g. to support user navigation using non-keyboard input devices.
-
I18N
WG/IG:
The "Television and the Web" IG
has to take into consideration the requirements for internationalization.
-
Mobile Access Interest
Group: The television community shares many technical interests and
requirements with the mobile community, such as subsetting HTML, or describing
device profiles. Both groups should use the same approaches and technologies.
-
RDF: The television community
is starting work on Metadata for audiovisual content (MPEG-7). RDF is one
potential contribution to this work.
-
Synchronized Multimedia:
Integrating Web content with television content often requires synchronization
between the two content types. The SMIL language may be able to express such
synchronization in a declarative way. It may fulfill the requirement for
accurate timing control in this area. Work on an API for controlling audio/video
streams and transition effects are part of
plans
for future work on an API by the former SYMM working group.
-
WAI:
Accessibility of Web content displayed on a TV set very important because
it potentially reaches a very large audience.
-
XML
WG: XML will be the basis
of any potential new markup language produced for the needs of television.
The limited memory size of TV settop boxes may require subsetting XML, e.g.
by eliminating internal entities.
The following is a list of groups that are known or presumed to be working
on or interested in integration of Television and Web technology, with pointers
to the respective projects.
-
ATSC (Advanced Television Systems Committee),
USA
-
ARIB (Association
of Radio Industries and Businesses), Japan
-
ATVEF (Advanced Television Enhancement
Forum), USA
-
CEMA (Computer and Electronics Marketing
Association), USA
-
published a specification on how to send URLs over Line21 VBI
-
DAVIC (Digital Video/Audio Council)
-
DVB (Digital Video Broadcast), Europe
-
EBU (European Broadcasting
Union)
-
IETF
-
Content
Negotiation Working Group: Defines a scheme for registering features
of display devices which can influence the type/form of content being delivered
to a display device. In many television scenarios, however, content negotiation
in the classical sense is not an option, since information is broadcast,
and there is no backchannel from individual receivers to the broadcast station.
-
IP over VBI
Working Group: Defines a scheme for transmitting IP over the vertical
blanking interval of analog television signals. This is listed only for
completeness, interaction with the W3C TVWeb IG is unlikely at this point.
-
IP over Cable
Data Network Working Croup: Deals with transmission of IP over cable
network.This is listed only for completeness, interaction with the W3C TVWeb
IG is unlikely at this point.
-
URL registration
Working Group: Defines a registration procedure for URL schemes, and
a set of guidelines on how to define URL-schemes.
-
ISO
MPEG-4
-
mpeg4-web mailing list: A mailing list to discuss potential areas of cooperation
between MPEG-4 and Web communities
(archive).
-
ISO
MPEG-7: A project in its initial phase for adding metadata to audiovisual
content. RDF could become relevant in this area.
The participants of the "Television and the Web"
IG communicate via a public, archived
mailing list, www-tv@w3.org
(archive).
Official membership in the IG is
open to all employees of
W3C
member organizations. There are no minimum requirements, neither in terms
of expertise, not in terms of time dedicated to the group. If the
IG decides to prepare a document,
the editor(s) will be asked to commit to a certain percentage of their time.
Non W3C Members
Employees of organisations that are currently not W3C members can participate
in the discussions on the IG's mailing list
www-tv@w3.org
(archive).
The TVWeb IG will be chaired by a W3C Team member (Philipp Hoschka). He will
also be W3C staff contact. Resources of additional W3C team members will
be required for some of the deliverables (review of "tv" URL schemes,
TV-specific subsets of HTML and CSS, Authoring guidelines etc.), should the
conditions for starting these deliverables be met .
Philipp Hoschka (ph@w3.org)