Overview

MPEG-4 is another ISO/IEC standard, developed by MPEG (Moving Picture Experts Group), the committee which also developed the Emmy Award winning standards of MPEG-1 and MPEG-2. While MPEG-1 and MPEG-2 video aimed at devising coding tools for CD-ROM and digital television respectively, MPEG-4 video aims at providing tools and algorithms for efficient storage, transmission and manipulation of video data in multimedia environments [1,2]. The main motivations behind such a task are the proven success of digital video in three fields of digital television, interactive graphics applications (synthetic image content) and the interactive multimedia (World Wide Web, distribution and access to image content). The MPEG-4 group believe these can be achieved by emphasising the functionalities of the proposed codec, which include efficient compression, object scalability, spatial and temporal scalability, error resilience, etc.

The approach taken by the experts group in coding of video for multimedia applications relies on a content-based visual data representation of scenes. In content-based coding, in contrast to the conventional video coding techniques, a scene is viewed as a composition of video objects (VO) with intrinsic properties such as shape, motion and texture. It is believed that such a content-based representation is a key to facilitating interactivity with objects for a variety of multimedia applications. In such applications, the user can access arbitrarily shaped objects in the scene and manipulate these objects.

The MPEG-4 group has defined the specifications of their intended video codec in the form of verification models (VM)...