In this paper,a Modified Discrete Cosine Transformation algorithm is provided,based on the analysis of the principle of AAC encoder in accord with the DRM standard,and this algorithm is implemented based on PC.

• 在分析符合DRM标准的AAC音频编码器原理基础上,提出了一种改进的离散余弦变换算法,并在PC上实现了基于该算法的AAC音频编码器。