Fast vector quantisation encoding algorithm using zero-tree data structure

A fast codeword search algorithm based on partial distance search (PDS) and zero-tree data structure is presented. Before the fast search, the zero-trees of the wavelet coefficients of codewords and sourcewords are first identified. The PDS is then preformed only over the wavelet coefficients which are not inside the zero-trees. The algorithm is well-suited to applications where degradation in average distortion is allowed to achieve very low arithmetic complexity.