AAC:21世纪音频编码的主流

数字音频编码技术无论对多媒体通信、多媒体广播、消费类电子都有其重要性。首先简要地回顾了数字音频编码技术的发展过程,然后介绍了包括MPEG音频,MP3,AC-3,ATRAC,PAC在内的8种现行商用数字音频编码系统,并作了特征比较,作为重点、详细地叙述了MPEG-2AAC的算法和特点。介绍了ITU-R有关高质量音频编码主观评价的方法,给出了AAC,PAC,MP3,AC-3音质评分表,评分显示在相同低数码率时AAC具有最好的音质,达到了ITU-R的有关规定。最后简要介绍了AAC的实现。

AAC-The Main Stream of Audio Encoding in the 21st Century

The technology of digital audio coding has its importance on multimedia commu-nications and multimedia broadcasting as well as consumer electronics.This paper looks back to the develomental progress of the technology of digital audio coding at first.The8kinds of cur-rent commercial audio coding systems including MP3,AC-3,ATRAC and PAC are introduced.The features of these systems are compared.The main point of this paper is to describe the algo-rithm and features of MPEG-2AAC in details.The subjective evaluation method of high quality audio coding based on ITU-R recommendation is introduced.The subjective quality score of AAC,PAC,MP3and AC-3is listed.Under the same low bit-rate,AAC has the highest audio quality than all other audio coding systems and fulfills the ITU-R requirements for"indistinguish-able quality".In the last the realization of AAC algorithm is briefly introduced.