Chapter 11: Content Description, Search and Delivery (MPEG-7 and MPEG-21)

Overview

As more and more audio-visual information becomes available in digital form, there is an increasing pressure to make use of it. Before one can use any information, however, it has to be located. Unfortunately, widespread availability of interesting material makes this search extremely difficult.

For textual information, currently many text-based search engines, such as Google, Yahoo, Altavista etc. are available on the worldwide web (www), and they are among the most visited sites. This is an indication of real demand for searching information in the public domain. However, identifying information for audio-visual content is not so trivial, and no generally recognised description of these materials exists. In the mean time, there is no efficient way of searching the www for, say, a piece of video concert by Pavarotti, or improving the user friendliness of interconnected computers via the Internet by rich-spoken queries, hand-drawn sketches and image-based queries.

The question of finding content is not restricted to database retrieval applications. For example, TV programme producers may want to search and retrieve famous events stored among the thousands of hours of audio-visual records, in order to collect material for a programme. This will reduce programme time and increase the quality of its content. Another example is the selection of a favourite TV programme from a vast number of available satellite television channels. Currently 6-8 MPEG-2 coded TV programmes can be accommodated in a satellite transponder. Considering that each satellite can have up to 12 transponders, each in horizontal and vertical polarisation mode and satellites can be stationed within two degrees guard band, it is not unrealistic that users may have access to thousands of TV channels. Certainly the current method of printing weekly TV programmes will not be practical (tens of thousands of pages per week!), and a more intelligent computerised way of choosing a TV programme is needed. MPEG-7, under the name of 'Multimedia content-based description standard', aims to address these issues and define how humans expect to interact with computers [1].

The increasing demand for searching multimedia content on the web has opened up new opportunities for creation and delivery of these items on the Internet. Today, many elements exist to build an infrastructure for the delivery and consumption of multimedia content. There is, however, no standard way of describing these elements or relating them to each other. It is hoped that such a standard will be devised by the ISO/IEC MPEG committee under the name of MPEG-21 [2].

The main aim of this standard is to specify how various elements for content creation fit together and, when a gap exists, MPEG-21 will recommend which new standards are required. The MPEG standard will then develop new standards as appropriate while other bodies may develop other relevant standards. These specifications will be integrated into the multimedia framework, through collaboration between MPEG and these bodies. The result is an open framework for multimedia delivery and consumption, with both the content creators and content consumers as the main beneficiaries. The open framework aims to provide content creators and service providers with equal opportunities in the MPEG-21 enabled market. It will also be to the benefit of the content users, providing them access to a large variety of data in an interoperable manner.

In summary, MPEG-7 is about describing and finding contents and MPEG-21 deals with the delivery and consumption of these contents. As we see, none of these standards are about video compression, which is the main subject of this book. However, for the completeness of a book on the standard codecs we briefly describe these two new standards that incidentally are developed by the ISO/IEC MPEG standard bodies.