Coding of arbitrarily shaped video objects in MPEG-4

MPEG-4 Visual, that part of the upcoming MPEG-4 standard describing the coding of natural and synthetic video signals, allows the encoding of video objects using motion, texture and shape information. In this paper, the shape coding algorithms and related texture coding algorithms that were thoroughly evaluated within MPEG-4 are reviewed. The evaluation leading to the selection of a block-based shape coder based on a context-based arithmetic encoder/decoder with motion compensation as well as padding and shape adaptive DCT for texture coding are presented.