MP3编码算法分析

MPEg-Ⅰ标准中规定了三层压缩方案，分别称为层1、层2和层3．层1方案实施起来最简单，但是压缩后的音质不如其它两层好；层3方案，即MP3编码，在低比特率时能得到最好的音质，由MP3编码的音乐文件适合在互联网上广泛传播，因此深受欢迎，但是它算法复杂，实施起来难度最大．本文通过介绍MPEG—Ⅰ标准中层3的数字音频编码方案，详细地分析了MP3算法中所采用的子带编码、心理声学模型和哈夫曼编码等关键技术，给出了实现上述关键技术的具体步骤，并且进一步提出了可以对编码方案进行细化的可行性建议，用以提高编码效率。

ANALYSIS OF MP3 CODING ARITHMETIC

The ISO MPEG-1 standard describes the implementation of three compression schemes called layer 1, layer 2 and layer 3. The layer 1 scheme is the simplest to implementation but its efficiency is not as good as the other two layers. The layer3 scheme, commonly known as MP3, provides the best performance at low bit rates and has become widely popular for the transmission of encoded audio file (MP3's) through the Internet. However, it is also the most difficult one to implement. This paper is designed to introduce the coding scheme for the MPEG-I layer3 standard. In this paper we analyze the key techniques adopted by MP3 coding arithmetic such as subband coding, psychoacoustic models and Huffman coding particularly and find out the approach to implement them. Furthermore, a feasible advice of improving the encoding scheme is proposed to make the code more efficient.