Improved vector quantization

Improved method and apparatus for vector quantization (VQ) to build a codebook for the compression of data. The codebook (600) or "tree" is initialized by establishing N initial nodes (610) and creating the remainder of the codebook as a binary codebook (650). Children entries (670) are split upon determination of various attributes, such as maximum distortion, population, etc. Vectors obtained from the data are associated with the children nodes, and then representative children entries are recalculated. This splitting/reassociation continues iteratively until a difference in error associated with the previous children and current children becomes less than a threshold. This splitting and reassociating process continues until the maximum number of terminal nodes is created in the tree, a total error or distortion threshold has been reached or some other criterion. The data may then be transmitted as a compressed bitstream comprising a codebook and indices referencing the codebook.