Animation of Synthetic Faces in MPEG-4

MPEG-4 is the first international standard that standardizes true multimedia communication including natural and synthetic audio, natural and synthetic video, as well as 30 graphics. Integrated into this standard is the capability to define and animate virtual humans consisting of synthetic heads and bodies. For the head, more than 70 model-independent animation parameters de$ning low-level actions like move left mouth corner up to high-level parameters like facial expressions and visemes are standardized. In a communication application, the encoder can dejne the face model using MPEG-4 BInaly Format for Scenes (BIFS) and transmit it to the decoder. Alternatively, the encoder can rely on a face model available at the decoder. The animation parameters are quantized, predictively encoded using an arithmetic encoder or a DCT. The decoder receives the model and the animation parameters in order to animate the model. Since MPEG-4 defines the minimum MPEG-4 terminal capabilities in pro$les and levels, the encoder knows the quality of the animation at the decoder.