Analysis of IMDCT fast algorithms

Modified Discrete Cosine Transform, with its perfect reconstruction and block effect cancellation property, has been adopted by most of current digital audio coding standards such as MP3, AC3, AAC and so on. However, it has very high computation complexity. Therefore, various efficient algorithms for the MDCT and IMDCT appeared in the last years. They are classified into two classes in this paper. The two classes of efficient algorithms for IMDCT are analyzed, and comparison between them is made in the following aspects: the speed, storage and word length requirement. In conclusion, algorithm based on DCT is faster than that based on FFT, but it needs longer word length; Both the DCT and FFT algorithms require 4.5N words memories. So this paper offers the way of choosing the proper IMDCT fast algorithm for different applications.