MPEG4 (Moving Picture Experts Group Compression Standard Version 4) is a technology for compressing voice, video and related control data and is one of the MPEG (Moving Picture Experts Group) international standards. It is currently a focus of attention due to the fact that it enables high speed and stable video transmission even in heretofore difficult environments such as mobile communication.
It is the most recent version of a standard for the digital representation of video, audio and certain types of 3D information. It processes detailed 3D representation for faces, human bodies and general 3D scenes.
For authors, MPEG-4 will enable the production of content that has far greater reusability, has greater flexibility than is possible today with individual technologies such as digital television, animated graphics, World Wide Web (WWW) pages and their extensions. Also, it will be possible to better manage and protect content owner rights.
For network service providers, MPEG-4 will offer transparent information which will be interpreted and translated into the appropriate native signaling messages of each network with the help of relevant standards bodies having the appropriate jurisdiction. However the foregoing excludes Quality of Service considerations, for which MPEG-4 will provide a generic QoS parameter set for different MPEG-4 media. The exact mapping for these translations are beyond the scope of MPEG-4 and are left to be defined by network providers. Signaling of the QoS information end-to-end, will enable transport optimization in heterogeneous networks.
For end users, MPEG-4 will enable many functionalities which could potentially be accessed on a single compact terminal and higher levels of interaction with content, within the limits set by the author. An MPEG-4 applications document exists which describes many end user applications including, among others, real time communications, surveillance and mobile multimedia.
MPEG-4 achieves these goals by providing standardized ways to:
1. represent units of aural, visual or audiovisual content, called "audio/visual objects" or AVOs. (The very basic unit is more precisely called a "primitive AVO"). These AVOs can be of natural or synthetic origin; this means they could be recorded with a camera or microphone, or generated with a computer;
2. compose these objects together to create compound audiovisual objects that form audiovisual scenes;
3. multiplex and synchronize the data associated with AVOs, so that they can be transported over network channels providing a QoS appropriate for the nature of the specific AVOs; and
4. interact with the audiovisual scene generated at the receiver’s end.
A number of functionality’s are provided to facilitate a wide variety of applications which could range from intelligible speech to high quality multichannel audio, and from natural sounds to synthesized sounds. MPEG-4 Audio supports the highly efficient representation of audio objects.
The MPEG-4 Visual standard will allow the hybrid coding of natural (pixel based) images and video together with synthetic (computer generated) scenes. This will, for example, allow the virtual presence of videoconferencing participants. To this end, the Visual standard will comprise tools and algorithms supporting the coding of natural (pixel based) still images and video sequences as well as tools to support the compression of synthetic 2-D and 3-D graphic geometry parameters (i.e. compression of wire grid parameters, synthetic text).
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