Extended lapped transforms: fast algorithms and applications

The author presents a fast algorithm for extended lapped transform (ELT), which is a modulated lapped transform (MLT) with longer basis functions. The proposed algorithm is based on a type-IV discrete cosine transform (DCT-IV). For AR (autoregressive) signals and also for real speech signals, the coding performance of the ELT is shown to be significantly higher than that of a block transform such as the DCT (discrete cosine transform), actually approaches the performance of ideal filter banks. Therefore, the ELT is a promising substitute for traditional block transforms in transform coding systems, and also a good substitute for less efficient filter banks in subband coding systems