No. 296 (October 2003)

Bookshelf Archive

The MPEG-4 Book

The title of this book is right – this is the MPEG-4 Book. The simple word "book" deserves to be capitalised here, as it embraces everything that the various "reference books", "handbooks", "encyclopaedias", "manuals" or indeed "bibles" could possibly contain. With some 850 pages, it is simply the authoritative "all-in-one" container of all the technical information on MPEG-4. It was compiled from contributions by 32 experts who have been not merely involved in the development of the MPEG-4 systems but were playing key roles in the whole process at its beginnings in 1996.

It is not an overstatement that MPEG-4 is the most recent and certainly the most advanced among the open international standards for audio and video coding systems. MPEG-4 is a member of the Moving Picture Expert Group which, in fact, is Working Group 11 of Subcommittee 29 (Coding of Audio, Picture, Multimedia and Hypermedia Information) of the joint ISO/IEC committee. As many broadcasters will be aware, two MPEG members, MPEG-1 and particularly MPEG-2, were the first two standards developed by the MPEG Consortium, both highly successful in the markets of digital television, video CD, MP3 audio and DVD.

The success of MPEG stems from the fact that it is a truly international effort in which more than 200 companies, universities, research centres, broadcasters and manufacturers are represented. MPEG has been so successful because it adopted simple and efficient "standardization principles", as follows:

• a toolbox approach (by which a standard must provide a minimum set of the tools assembled across the industry);
• "one functionality, one tool" approach;
• relocation of tools and algorithms;
• maximum interoperability;
• minimum complexity and cost.

The book is more than just a reproduction of the MPEG-4 standard, known as ISO/IEC 14496. It takes the reader through the whole process of standardization, outlines the requirements, discusses the various technical solutions, provides some background information (which will be highly appreciated by the non-initiated) and is very comprehensive. In particular, MPEG-4 tools and applications are described to some detail.

The MPEG-4 standard was conceived from the need to develop a very efficient, low-bitrate coding system which could be used in mobile, web, broadcast, rich virtual and broadband environments. In this manner, MPEG-4 complements the other two members of the MPEG family, MPEG-1 and MPEG-2, which cover bitrates from 1.5 Mbit/s upwards.

MPEG-4 is much more than an efficient source coding system. One of the its most important concepts is that it is based on audiovisual objects which can be conveyed through a number of streams to a receiver where they are reconstructed and rendered for presentation. All objects in the presentation are described by the Object Descriptor (OD) framework. In order to assemble the media objects into a specific audiovisual scene, a scene description was conceived. It is called BIFS (Binary Format for MPEG-4 Scenes). BIFS conveys the spatio-temporal layout of the media objects in the scene. The syntax of the OD framework uses the Syntactic Description Language (SDL).

The content description of media objects is given by two auxiliary streams: the OCI (Object Content Information) stream, which carries object metadata, and IPMP (Intellectual Property Management and Protection) which provide hooks to control the legitimate usage of the MPEG-4 format. The timing information of the different object streams is conveyed by the Synchronization Layer (SL).

MPEG-4 terminals may vary from wireless and handheld devices to high-quality TV set-top boxes. As the computational differences of these terminals may be considerable, common application software – based on Java – is used. This is called MPEG-J and it defines a set of APIs that enable the application to interact with the terminal and its environment, in terms of the delivery of the application to the client terminal, its scope, life cycle and security restrictions.

The eXtensible MPEG-4 Textual (XMT) format is a framework for representing MPEG-4 systems' content and associated audiovisual streams using a textual syntax. XMT is based on W3C's XML (eXtensible Markup Language). XML provides an exchangeable format between content authors. It can also serve for machine-generated content production using multimedia database material and templates.

It is interesting to note that the MPEG-4 Consortium did not develop a specific transport mechanism to carry MPEG-4 content. Instead, existing transport protocols – provided by MPEG-2 and Internet Protocol (IP) – can be used. However, MPEG-4 has developed its own storage format known as MPEG-4 file format. This is largely based on Apple's Quick Time. An abstraction layer for the delivery of the MPEG-4 streams and files was also developed; it is called Delivery Multimedia Integration Framework (DMIF). Thus, in MPEG-4, delivery is the term that encompasses both storage (file format) and transmission protocols.

The book gives a clear review of the available MPEG-4 profiles and levels. Whereas the profile defines the toolset used, the level defines the bounds of complexity that can be expected in the bit stream for a particular profile. A profile and level combination gives a well-defined conformance point which serves as a check point to determine whether implementations of the standard really operate according to the specification.

It goes without saying that MPEG-4 has also developed its own video and audio compression (coding) algorithms. These are widely known to broadcasters; therefore they do not need to be addressed in this book review. Suffice to say, the book provides a very detailed coverage of this topic, involving some 300 pages of densely packed text. The book provides extensive reports on subjective and objective evaluations of the different commercial implementations of MPEG-4 audio and video codecs.

Two final remarks

Firstly, the book was published in 2002, so no details of MPEG-4 Part 10, now known as H.264, are given. H.264 was finalised by the Joint Video Team (JVT) in July 2003.

Secondly, the book does not address the Intellectual Property Rights (IPR) issues relating to MPEG-4. The latter point is controlled by MPEG LA (for video) and Via Licensing (for audio). If not resolved satisfactorily for broadcasters, IPR may become a major stumbling block to the commercial success of MPEG-4 in the market. The danger is that a proprietary standard, such as Microsoft Windows Media, may benefit from unresolved IPR issues of MPEG-4 and occupy an important market share.

It is to be hoped that a second edition of this excellent book addresses these two important issues.

The MPEG-4 Book
Edited by Fernando Pereira and Touradj Ebrahimi
Hardbound volume of 849 pages
ISBN 0-13-061621-4. Price: £55.99
IMSC Press Multimedia Series, Prentice Hall PTR, 2002
http://www.pearsoned.co.uk/Bookshop/detail.asp?item=244194

Franc Kozamernik

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Standard Codecs: Image Compression to advanced Video Coding

This publication is probably the most recent and up-to-date book on video coding in the European book market. It is an interesting technical book, giving in-depth information on video coding algorithms and technologies. It provides very comprehensive fundamentals on the video formats that led to the developments of a number of commercially successful codecs, such as the H.261 videoconferencing system, H.262, H.263, H.263+, H.263++, MPEG-4 and finally H.264.

The main value of this book is that it reviews extensively the basics of video and includes the fundamental elements of video compression such as DCT (discreet cosine transform), temporal redundancy reduction (such as motion compensation) and variable length coding techniques (such as Hoffman and arithmetic coding).

Of particular interest is an extensive chapter on wavelet coding. Wavelet codecs are likely to become very important in the near future and may represent a new quantum leap in the development of video codecs. Three wavelet-based codecs are described: EZW, SPIHT and EBCOT.

The coding of still pictures, carried out by the JPEG codec, can also be important for broadcasters. A new standard, known as JPEG2000, can provide improved picture quality and additional functionalities.

The most important section of the book is Chapter 9 which describes H.263 and its successor, H.264. This chapter also includes the all-important methods for improving the robustness of the codec against channel errors.

Finally, the book describes the novel methodology for video coding based on image content, i.e. MPEG-4 including Video Object Plane (VOP), image segmentation, shape coding, texture coding, coding of the background, coding of synthetic objects, and scalability.

The last chapter is devoted to content description, search and delivery, i.e. MPEG-7 and MPEG-21.

This book should be very useful to practising broadcast engineers involved in television, video, broadband and internet engineering, as it gives a lot of useful and practical tips. Of particular value are the numerical problems given at the end of each chapter, helping readers to deepen their understanding of the subject.

All in all, a highly recommended book.

Standard Codecs: Image compression to advanced Video Coding
Mohammed Ghanbari
Hardbound volume of 407 pages
ISBN 0-85296-710-1. Price: £55.00.
Institution of Electrical Engineers, London, 2003
http://www.iee.org/shop/invoke.cfm?objectID=A2A91DE4-3B19-400A-B92B3F9820446AC3&method=displayDetails

Franc Kozamernik

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Broadband applications and the digital home

As "broadband" is rolling out rapidly in many European countries and worldwide, the publication of this book could not be more timely.

The term "broadband" means different things to different people. "Broadband is more bandwidth than you can use", said Mark Bagley of Venation, the web-acceleration company . In this book, "broadband" stands for a digital communication technology (such as ADSL – Asymmetric Digital Subscriber Line) which can convey new applications to the user at home via an "always-on" connection using a copper telephone line. The emphasis is on the word "new": this book's focus is on the very diverse applications that may range from some telecom services (such as home automation, surveillance, maintenance and monitoring, VoIP) to interactive entertainment services (video and films on demand, games, multichannel television and radio, fast internet, etc). The targeted reception terminal is a Personal Computer (PC), although television sets – suitably equipped with a dedicated set-top box (STB) and a simple remote control, rather than a keyboard – are becoming more and more popular, even for non-media applications.

One vision of broadband outlined in the book is that it could contain searchable media about "almost every imaginable subject". This vision is not too dissimilar to the current Internet paradigm: the Internet contains information about "almost every imaginable subject". For example, a quick search over broadband on a particular subject could turn up every music item or documentary or film made about that subject.

Unlike the WWW (which is truly worldwide), broadband makes it easier to satisfy the requirements of copyright holders – due to its restricted geographical reach (e.g. local or city-wide only).

Some broadband networks can be specially designed to carry several tens of television channels of conventional quality to an STB or television set. Several trials of this are being conducted in Europe and elsewhere to ascertain the technical and commercial viability. To this end, broadband has recently raised a lot of discussion among broadcasters . Many broadcasters consider it as an opportunity to bring their programmes to viewers' homes through new channels, and thus provide new revenue opportunities. Other broadcasters are afraid of potential competition to their television services and are strongly opposed to ADSL television.

Several broadcasters are running trials involving several hundreds of home users and families. These trials are being conducted in collaboration with their telecom partners in order to assess the various business models. In some cases, these trials are being used as an argument for not investing in terrestrial digital television, thus deferring the introduction of DVB-T in their countries. Nevertheless, it is clear that DVB-T and ADSL TV are two different services and both have their strong and weak points. Therefore, both are needed. For example, if portable and mobile reception is required, DVB-T is a better solution. If interactive TV is required, broadband (which is, by its very nature, two-way) could be a better solution.

The book is grouped into five parts:

Part 1: Delivery to the home – connecting the home to external networks;

Part 2: Networking the home – connecting devices and applications within the home;

Part 3: Living in the digital home – how people use the technology and how technology meets their needs;

Part 4: Applications – which applications can be attractive;

Part 5: The future digital home – what is to come in the future.

The book provides the reader with an insight into what the digital home is likely to look like in the future ... which broadband services will be available ... and which are the key enabling technologies. As it has been written by telecom people (most of the 41 authors come from BTexact Technologies), the book reflects the views of the telecom community, slightly neglecting the broadcasters' views. For example, it is the broadcasters' view that MHP (Multimedia Home Platform) should be the future universal API platform. However the book mentions MHP only in one section as a possible option. Live television services are reduced to one service among several tens of others. Conventional STBs and TVs are replaced by a home media center/home gateway to communicate services not only to TV sets but also to laptop and desktop computers, digital cameras, mobile phones, DVD players, stereo stacks, games consoles, PDAs and other domestic appliances.

The book concludes that the future home will be "intelligent, connected and wireless". A smart fridge could automatically order fresh milk when the existing supply has passed its best-before date. There have been more useless gadgets invented in the last few years than in any period of human history. Only products that take good account of basic human needs and nature will be successful in the market-place. Many existing visions of the future home are based too much on technological capability and take too little account of human nature and every-day life styles, and therefore are doomed to failure. Many of the products hyped for the future home will never achieve significant market success.

Our homes will be smarter than today's but may become infested by myriads of invisible activators and agents – designed to enhance many areas of our lives. There is, however, potential danger that machines could escape from our control, so we must be careful to develop suitable control mechanisms.

In summary, this interesting and well-written book is highly relevant for broadcasters. One of the messages is that media delivery will be facilitated by broadband and that broadband is likely to change the patterns of media consumption. Another message is that radio and television will have to compete with a myriad of other services delivered via broadband and available in the all-digital home.

Broadband applications and the digital home
Edited by John Turnbull and Simon Garrett
Hardbound volume of 379 pages
ISBN 0-85296-428-5. Price: £55.00
Institution of Electrical Engineers, London, 2003
http://www.iee.org/shop/invoke.cfm?objectid=E63259A3-7185-4A16-BEA3762C9DCAF99F&method=DisplayDetails

Franc Kozamernik

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European Broadcasting Union L'Ancienne Route 17A CH-1218 Grand-Saconnex Geneva Switzerland techreview@ebu.ch