基于 MPEG-AAC 编码器的压缩域音频增强方法

摘要

An audio enhancement method based on MPEG-AAC codec in compressed domain is proposed .First ,the bit-stream derived from noisy audio signal is decoded to obtain MDCT coefficients of noisy audio signals .Then ,the noise power is esti-mated by modified weighted recursive averaging (MWRA) .Next ,the adaptive β-order COSH statistic modal method is employed to enhance MDCT coefficients .Finally ,the enhanced MDCT coefficients are re-quantized to obtain an enhanced bit-stream which is used to get the enhanced audio signals by AAC decoder .The test results indicate that the proposed algorithm can effectively remove the noises derived from AAC bit-stream of audio signals and obviously outperforms the reference noise reduction methods .%本文基于 MPEG-AAC 音频编解码器，提出了一种压缩域的音频增强方法。首先，对含噪音频信号的比特流进行解码，得到含噪音频信号的 MDCT 系数；然后，利用修正的加权递归平均（Modified Weighted Recursive Averaging ， MWRA）方法估计噪声功率；再者，利用基于听觉掩蔽原理的自适应β-阶双曲余弦（COSH）统计模型，对含噪音频的MDCT系数进行增强处理；最后，将增强后的 MDCT 系数重新量化编码，得到用于解码的增强比特流实验结果表明，本文提出的方法能有效去除 AAC 解码音频信号中的多种背景噪声，其性能明显优于参考方法。