Improved algorithm for efficient computation of the forward andbackward MDCT in MPEG audio coder

摘要

Britanak and Rao (see IEEE Signal Processing Lett., vol. 8, p.n48-51, Feb. 2001) recently proposed an efficient algorithm to implementnthe forward and backward modified discrete cosine transform (MDCT) innMPEG layer III. This algorithm employs discrete cosine transform of typenII (DCT-II) and discrete sine transform of type II (DST-II) to computenthe forward MDCT, and uses their inverses to compute the backward MDCT.nThe author presents an improved algorithm to implement the forward andnbackward NEXT in MPEG layer III. Notably, the proposed algorithmnrequires less calculation than Britanak and Rao's algorithm does.nFurthermore, it employs the same module to compute both the forward andnbackward MDCT. Thus, when compared to the former algorithm, the proposednalgorithm is implemented more easily