MPEG-4 TECHNOLOGY

MPEG-4 TECHNOLOGY

INTRODUCTION:

MPEG-4 is an ISO/IEC standard developed by MPEG (Moving Picture Experts Group) . These standards made interactive video on CD-ROM, DVD and Digital Television possible. MPEG-4 is the result of another international effort involving hundreds of researchers and engineers from all over the world. MPEG-4, with formal as its ISO/IEC designation 'ISO/IEC 14496', was finalized in October 1998 and became an International Standard in the first months of 1999. The fully backward compatible extensions under the title of MPEG-4 Version 2 were frozen at the end of 1999, to acquire the formal International Standard Status early in 2000. Several extensions were added since and work on some specific work-items work is still in progress.
MPEG-4 builds on the proven success of three fields:
• Digital television;
• Interactive graphics applications (synthetic content);
• Interactive multimedia (World Wide Web, distribution of and access to content)
MPEG-4 provides the standardized technological elements enabling the integration of the production, distribution and content access paradigms of the three fields.
The standard, developed over five years by the Moving Picture Experts Group (MPEG) of the Geneva-based International Organization for Standardization (ISO), explores every possibility of the digital environment. Recorded images and sounds co-exist with their computer-generated counterparts; a new language for sound promises compact-disk quality at extremely low data rates; and the multimedia content could even adjust itself to suit the transmission rate and quality.
Possibly the greatest of the advances made by MPEG-4 is that viewers and listeners need no longer be passive. The height of "interactivity" in audiovisual systems today is the user's ability merely to stop or start a video in progress. MPEG-4 is completely different: it allows the user to interact with objects within the scene, whether they derive from so-called real sources, such as moving video, or from synthetic sources, such as computer-aided design output or computer-generated cartoons. Authors of content can give users the power to modify scenes by deleting, adding, or repositioning objects, or to alter the behavior of the objects; for example, a click on a box could set it spinning.
Perhaps the most immediate need for MPEG-4 is defensive. It supplies tools with which to create uniform (and top-quality) audio and video encoders and decoders on the Internet, preempting what may become an unmanageable tangle of proprietary formats. For example, users must choose among video formats such as QuickTime (from Apple Corp., Cupertino, Calif.), AVI (from Microsoft Corp., Redmond, Wash.), and RealVideo (from RealNetworks Inc., Seattle, Wash.)--as well as a bewildering number of formats for audio.
In addition to the Internet, the standard is also designed for low bit-rate communications devices, which are usually wireless. For example, mobile receivers and "Dick Tracy" wristwatches with video will have far greater success now that the standard is in place. But whether wired or not, devices can have differing access speeds depending on the type of connection and traffic. In response, MPEG-4 supports scalable content, that is, it allows content to be encoded once and automatically played out at different rates with acceptable quality for the communication environment at hand.
On the other end of the quality/bit-rate scale, future television sets will no doubt accept content from both broadcast and interactive digital sources. Accordingly, MPEG-4 provides tools for seamlessly integrating broadcast content with equally high-quality interactive MPEG-4 objects. The expectation is for content of broadcast-grade quality to be displayed within World Wide Web screen layouts that are as varied as their designers can make them. However, the standard's potential for encoding individual objects with the extremely high quality needed in studios has the recording industries very much on the alert.
Recently, digital copying of audio from the Internet has become a popular and--to the music industry--increasingly worrying practice. For video, the same situation will arise when MPEG-4 encoding and higher bandwidths become widespread and as digital storage prices continue to drop. Accordingly, MPEG designed in features for protection of intellectual property and digital content


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