一种新的MDCT快速算法

改进型的离散余弦变换（Modified disrete cosine transform）作为良好的时频分析工具在单频编码中广泛应用。本文提出了一种基于快速DCT变换的MDCT快速算法，与其他文献的算法相比，其运算量明显减少。

A New Fast Algorithm of MDCT

The modified discrete cosine transform (MDCT) is a part of the time domain aliasing cancellation (TDAC), and it becomes a key technique in high quality audio coding. In MPEG4, both MPEG 2 AAC and TwinVQ treat MDCT as an important filterbank tool. In some practical applications, such as digital audio station (DAS) and Studio, the computation speed of the coder is crucial. Therefore, we present a DCT based fast algorithm of MDCT, while the former ones are FFT based. All the operations of the proposed algorithm are real value operations, while those of FFT based algorithm are complex value operations. Due to its unique half butter fly core and symmetry, fewer operations and less memory are needed in the new algorithm than those in References. The proposed algorithm is suitable for float point implementation. The results show that faster computation speed is achieved using the new algorithm. This new algorithm can be introduced not only in high quality audio coding, but also in speech coding and other signal processing applications with similar filterbank tools.