Efficient hybrid coding of video for low bitrate applications

A novel video codec for low-bit-rate applications is proposed. The main characteristics of the codec are the use of a space-variant wavelet packet decomposition for energy compaction in the spatial domain and the introduction of a locally adaptive multigrid motion estimation technique. The use of a mesh adaptive multigrid block matching technique for motion estimation reduces both the energy of the prediction error and the amount of the side information for transmitting the appropriate motion field. Accordingly, an adaptive compaction of the energy in the spatial domain using wavelet packets makes it possible to decide the nature of the desired transformation depending on the nature of the incoming signal (intraframe or prediction error). Simulation results show that a significant gain in compression is obtained with this coding scheme compared to a codec based on a dyadic wavelet decomposition and a fixed block size block matching, while maintaining the same quality of reconstructed data