64 kbit/s Video coding algorithm using adaptive gain/shape vector quantization

A hybrid coding algorithm, consisting of motion compensated interframe prediction and adaptive gain/shape vector quantization, is proposed for low bit rate video coding. A video coding system using the proposed coding algorithm and its coding characteristics are also described. Motion compensated interframe prediction is an efficient technique for reducing temporal redundancy contained in moving pictures. In the proposed scheme, constant amplitude blocks ("gray level blocks") are also included in search vectors in order to increase coding efficiency for quick object movement or scene change. Adaptive gain/ shape vector quantization with a tree search codebook is employed to encode motion compensated interframe difference signals. It can respond to changes in source statistics because its codebook is independent of the gain components of the input vectors. The proposed coding algorithm has been evaluated by computer simulations and shown to be effective for low bit rate video transmission. A 64 kbit/s video coding system based on this coding algorithm has been implemented. The developed coding system can transmit multiplexed video, audio and digital data at the basic ISDN rate, and can be applied to videophone as well as videoconferencing.