Abstract
MPEG is the famous four-letter word which stands for the "Moving Pictures Experts Groups. To the real word, MPEG is a generic means of compactly representing digital video and audio signals for consumer distributionThe essence of MPEG is its syntax: the little tokens that make up the bitstream. MPEG's semantics then tell you (if you happen to be a decoder, that is) how to inverse represent the compact tokens back into something resembling the original stream of samples.
Description of MPEG Video Compression
MPEG-4 is an ISO/IEC standard being developed by MPEG (Moving Picture Experts Group), the committee which also developed the Emmy Award winning standards known as MPEG-1 and MPEG-2. These standards made interactive video on CD-ROM and Digital Television possible. MPEG-4 will be the result of another international effort involving hundreds of researchers and engineers from all over the world. MPEG-4, whose formal ISO/IEC designation will be ISO/IEC 14496, is to be released in November 1998 and will be an International Standard in January 1999. MPEG-4 is building on the proven success of three fields: digital television, interactive graphics applications and the World Wide Web.
2D ANIMATED MESHES
A 2D mesh is a tessellation (or partition) of a 2D planar region into polygonal patches. The vertices of the polygonal patches are referred to as the node points of the mesh. MPEG4 considers only triangular meshes where the patches are triangles. A 2D dynamic mesh refers to 2D mesh geometry and motion information of all mesh node points within a temporal segment of interest. Triangular meshes have long been used for efficient 3D object shape (geometry) modeling and rendering in computer graphics.
2D mesh modeling may be considered as projection of such 3D triangular meshes onto the image plane.A dynamic mesh is a forward tracking mesh, where the node points of the initial mesh track image features forward in time by their respective motion vectors. The initial mesh may be regular, or can be adapted to the image content, which is called a content-based mesh . 2D content-based mesh modeling then corresponds to non-uniform sampling of the motion field at a number of salient feature points (node points) along the contour and interior of a video object. Methods for selection and tracking of these node points are not subject to standardization.
