Adaptive hybrid transform for signal analysis and synthesis

Analysis and synthesis filter banks such as those used in audio and video coding systems are each implemented by a hybrid transform that comprises a primary transform in cascade with one or more secondary transforms. The primary transforms for the filter banks implement an analysis/synthesis system in which time-domain aliasing artifacts are cancelled. The secondary transforms, which are in cascade with the primary transforms, are applied to blocks of transform coefficients. The length of the blocks is varied to adapt the time resolution of the analysis and synthesis filter banks. One or more sets of hybrid-transform coefficients resulting from a secondary transform are enoded the. The length of the secondary transform is adapted in response to the block-length control signal. One or more sets of hybrid-transform coefficients are quantized according to a perceptual model to generate encoded information.