Developments in model-based video coding

This paper reports on current developments in the area of model-based video coding, a technique which shows promise of achieving very large bit-rate reductions for moving images. After an introduction and historical review, advances are summarized in several areas, among them improved 3D tracking of the human head and of facial expressions, the use of muscle-driven model animation with skin synthesis, techniques for luminance compensation, and switched coders. Bit rates ranging from 64 kb/s down to about 1 kb/s have been obtained using head-and-shoulder video sequences. Problems with model-based methods are identified and future developments in both CBR and VBR transmission discussed