Fast Algorithm for Modulated Complex Lapped Transform

A new algorithm for the modulated complex lapped transform (MCLT) with a sine windowing function is presented. It is shown that by merging the windowing operation with the main computation, both the real and the imaginary parts of the MCLT with 2N inputs can be obtained from two N-point discrete cosine transforms of type II (DCTs-II) of appropriate inputs. The resulting algorithm is computationally very efficient. In general, the value of N is an even number. When N is a power of 2, the proposed algorithm uses only N log N + 2 real multiplications (including the scaling factors in the DCT computation), with none of those being outside the DCT blocks.