W3C Workshop "Television and the Web"
Position Paper:
A View to the Broadcasting and the Internet
leading the Broadcasting to its full potential...
Yoshihisa GONNO*
Information Broadcasting Laboratories, Inc.
1-1-1, Nishi-Asakusa, Taito-ku, Tokyo, 111-0035, Japan
*partly on loan from Sony Corporation, Tokyo, Japan
Abstract:
The rapid transition of broadcasting systems from analog to digital has been predicting the possibility of integrated services with the digital broadcasting and the Internet. In order to make the most use of the digital information infrastructure, a variety of forms of information must be well-structured from every point of view such as authoring, delivery, browsing, searching and retrieval. In this sense we define Information Broadcasting as a broadcasting service provided with highly structured information. In this paper we propose a view to the future of information distribution infrastructure and technical issues for the architecture of global and seamless information networks by means of metadata structuring technology between the Broadcasting and the Internet.
Introduction:
increasing number of services leads to metadata structured directory
service
As infrastructures of digital information network are expanding and
improving rapidly, numerous number of services are going to be provided
on the Broadcasting and the Internet. Millions of Web sites are already
provided on the Internet. Digital satellite broadcasting systems are now
about to provide hundreds of TV and Radio channels. People are loosing
ways to remember channel numbers of favorite TV programs and URLs of favorite
Web applications. The majority of TV users and novice PC users will be
paralyzed in floods of TV programs and Web applications. Under the circumstances
people will need to be well-navigated by sophisticated directory services
to find and access the objects which are not only actually wanted but also
potentially desired. Performing such navigation will require to disseminate
appropriate information about any kinds of contents efficiently and seamlessly
between the Broadcasting and the Internet, which we call metadata structured
directory service.
increasing number of users leads to broadcast-based information distribution
In the meantime reducing the cost of terminals like set top boxes (STBs)
and personal computers (PCs) is accelerating the growth of the number of
users to millions and zillions. These users are expected to have different
terminal resources from small STBs to high-performance PCs, and are supposed
to use in different manners such as with his family or by himself, on the
couch or at the desk. Broadcasting systems, taking the topological advantage,
have been providing TV and Radio contents distribution for millions of
people. Cutting-edge multimedia Web applications are also intending to
be provided with multicast capability on the Internet. In order to provide
directory services and contents distribution for millions of people efficiently,
broadcast-based information distribution mechanisms are expected to provide
a lightweight protocol framework for metadata distribution and content
distribution.
Underlying Circumstances:
learning from the Broadcasting
It is important to learn from the nature of information on TV and Radio.
* streaming information media
Historically broadcasting contents such as TV and Radio program has
been implemented in streaming-based protocols, which are optimized only
for transportation and presentation of audiovisual contents. Taking an
advantage of connectionless communication, broadcasting systems can perform
congestion-free information transportation. This is one of major advantages
of broadcast-based transportation.
* poorly-structured information transport
In order to transport the information just for presentation of audiovisual
streams, there has been no need to structure the information to high extent
during transportation. Information on the broadcasting has been mapped
only on the frequency bandwidth called 'channel'. A directory service on
the broadcasting system named EPG, electronic program guide, is now expected
to provide schematic structures for the information on the broadcasting.
* topological advantage of on-air broadcasting
It is impossible to know how many people are about to receive broadcasting
contents and where they are located in advance of transmission. Under the
circumstances broadcasting on the air can disseminate information from
a few servers to millions of public clients effectively by the nature of
its propagation mechanism in the air. Clients just need to filter and extract
preferred information out of the stream transmitted from servers, which
performance is independent of the number of clients. Note that this is
one of the greatest advantages of on-air broadcasting.
learning from the Internet
There are also things to learn from the nature of the Internet.
* interactive communication media
This aspect is an essential property, which provides negotiation opportunity
for communication between servers and clients. While this allows us to
deliver the information on demand, it is potentially inevitable that rush
of clients may cause congestion of servers. This can be a fatal problem
particularly in case of live applications.
* highly-structured information transport
Such interactivity allows us to implement a various kinds of protocols,
such as FTP, HTTP or RTSP, depending on the application on the IP-based
single network namely the Internet. These protocols can be optimized for
the corresponding applications, which appears to be well-structured on
the Internet protocol layers.
* routing-based information transportation
In contrast with the on-air broadcasting, the IP-based wired network
needs to perform packet routing in order to deliver specific information
to designated clients. This will potentially cause network contention against
unexpected peak concentration even if routing process gets faster and network
bandwidth grows wider.
Requirements:
Keeping these aspects in mind, following points should be considered toward the unification of the Broadcasting and the Internet.
generality of description
Any kind of information should be described about any type of resources
of information by descriptors. A descriptor is a representation of metadata.
Metadata allows us to search desired information without parsing whole
information. While a descriptor may have its own format or syntax optimized
for transport systems or storage systems, it should be transformed into
each other schematically. Some might be optimized for the IP system, the
other might for the MPEG-2 system and the other might for file systems
or database systems.
seamless linking
As linking information is also a type of resources of information,
a descriptor may represent a link to other resources of information. Some
might be linked to a web object represented by a URL, the other might to
a broadcasting object represented by a program identifier. Some might be
linked to a remaining object like a static file, the other to a streaming
object like an audiovisual live program. Any type of linking should be
described in universal expression.
metastructure representation
Metadata has a logical or semantic structure, which is called metadata
schema. With different metadata schemas, distributed web and broadcast
objects can be organized into multiple metastructures. Metastructures can
be formed not only between distributed objects apart from each other but
also inside individual objects. This allows not only static documents but
also continuous audiovisual streams to be segmented and to be restructured
into virtual structures namely metastructures.
metadata transport protocol
Not only descriptors of metadata but also metadata schemas must be
transported to millions of clients efficiently. Since these auxiliary data
are anticipated running to a considerable amount, metadata transport protocols
should be optimized for transport systems. This function should be associated
with data filtering and data updating mechanisms on individual terminals.
filterable metadata coding
As a way to optimize metadata transport protocols, metadata can be
compressed and coded into binary data suitable for broadcast-based systems.
Highspeed and lightweight filtering schemes should be implemented with
a sophisticated coding system. This aspect is practically important especially
for low price STBs to filter preferred data out of highspeed broadcast
streams efficiently.
distributed object management
Broadcast-based protocols can be applied for distributed object management
systems, which are expected not only to perform lightweight metadata structured
directory services but also to provide a distributed database management
framework.
All these aspects expected to be standardized making the most use of de facto technologies. Too much heavy standards will not gain in popularity because of difficulty of implementation.
Related Activities:
metadata description and metadata structured directory service
On the Internet there has been DNS as a directory service, which is
provided by poorly-structured metadata about the domain name system. Now
we are going to be able to describe highly-structured metadata about general
type of web objects by means of RDF, which not only allows search engines
to surely hit desired objects, but is also capable of providing directory
services in a broad sense. RDF can potentially describe any kind of metadata
about any type of information including TV and Radio contents.
On the digital broadcasting MPEG-2 provide a data coding system for
audiovisual presentation, which is optimized for transport audiovisual
streams. DVB is proposing a framework to describe and transport metadata
called service information including EPG on the MPEG-2 system. MPEG-4 will
provide effective compression and transport mechanisms for digital data
streams by describing individual components of audiovisual data streams.
MPEG-7 is intending to generalize such kinds of descriptions and to provide
a metadata description standard for digital broadcasting systems. First
CFP is scheduled on this October and there is no full-scale activity yet.
These separated activities are expected to be intercommunicated in
order to establish a standard fit for practical use. W3C workshop "Television
and the Web" is expected to be a good chance to bring up a new activity
at W3C toward the unification of the Broadcasting and the Internet.
Our Objectives:
leading the Broadcasting to its Full Potential...
From every point of view proposed in this paper, we will contribute
to and affect the standardization activities in collaboration with our
capital companies. The key idea of metadata broadcasting framework was
proposed as "Requirements for Metadata Handling" from Sony to DAVIC 11th
CFP on interactive multimedia services based on in-home storage. DAVIC
established the ad-hoc groups related this technology called Meta-Data
ad-hoc in INR-TC and Local Storage based Multimedia Application ad-hoc
in SII-TC. Our proposal will soon be focused by corresponding WGs at ARIB,
Association for Radio Industries and Businesses, which will affect on Japanese
broadcasting standard. The activity of MPEG-7, which will focus on metadata
description for information search, is also our target. Most of the statements
proposed in this paper are not contradictory to the objectives of MPEG-7
except that we are aware of the importance of interconnectivity between
the Broadcasting and the Internet. Boundary province among these activities
is expected to be focused by W3C. Furthermore, extending the idea of metadata
broadcasting framework, we will propose a framework for distributed information
management applicable to distributed directory services and distributed
database services.
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Yoshihisa Gonno, Research Scientist
Information Broadcasting Laboratories, Inc. #temporary affiliate
tel:+81-3-5826-7383 fax:+81-3-5826-7382 email:ygonno@ibl.co.jp
Network Technology Lab, I T Labs, Sony Corp. #permanent affiliate
tel:+81-3-5448-4423 fax:+81-3-5448-4327 email:ygonno@arch.sony.co.jp