Low bit-rate hybrid coder using hierarchical motion compensation and low complexity vector quantization

An investigation is conducted of the problem of providing low-cost compression of video sequences to be used in applications like video sessions between workstations. An evaluation of a hybrid coder for very low bit-rate (64 Kb/s) coding, based on vector quantization of the motion-compensated prediction where only the regions that exhibit noticeable changes between successive frames are coded and transmitted, is presented. Motion compensation (MC) is performed in three steps, over successive subband decompositions of the subsequent frames. Such a hierarchical MC technique substantially reduces the complexity with respect to classical MC, due to the subsampling of the subbands. Vector quantization is applied to the coding of the motion-compensation prediction error blocks. Fast search VQ algorithms are used to achieve a low complexity coding