A variable resolution video codec for low bit-rate applications

Demand for interpersonal video and audio communication at bit rates available on basic and subprimary ISDN accesses is growing and it is expected that service implementation will require large numbers of low-cost high-quality equipment. This paper describes the concept and simulation results of a coding scheme of the hybrid (intraframe transform and temporal DPCM) type whose main feature is the possibility of regaining high resolution for slowly changing pictures. Methods for controlling the spatio/temporal resolutions and simulation results are given. A byproduct of the algorithm allows the reduction of the transmission buffer to negligible values