【作者】 王伟；

【导师】 国澄明；

【作者基本信息】 天津大学 ， 信号与信息处理， 2008， 硕士

【摘要】 AVS音频标准是我国具有自主知识产权的音视频编码标准AVS的第三部分,为高质量音频压缩领域提供了很好的方案,主要用于高分辨率数字广播、高密度激光数字存储媒体、无线宽带多媒体通讯和互联网宽带流媒体等业务。AVS音频编码标准中引入了许多先进的音频编码技术,研究AVS音频编码技术及其实时实现对AVS音频标准的推广和应用具有重大的现实意义。本文首先介绍了音频编码技术的发展情况和基本原理,对AVS音频编解码的框架和各个模块的算法进行了研究和分析。针对AVS音频编码算法中暂态信号处理的复杂度较高的缺陷,提出了两种新的暂态信号处理方法,并在AVS音频编解码器中进行了验证,实验证明,这两种方法的编码质量和原来编码器的质量相当,但计算复杂度却远远低于原来的编码器。然后,本文对AVS音频编解码器的各个模块进行了优化,使得AVS音频编解码器的计算复杂度大大降低。接下来,将AVS音频编码器移植到DM642 EVM平台上并进行优化,在该平台上实现音频的实时采集,实时编码以及编码比特流的实时发送;将AVS音频解码器移植到DSK5416平台上并进行优化,实现编码比特流的实时接收,实时解码和音频数据的实时播放。编解码器的优化结果是,在44.1kHz采样率下,实时编码需要150MHz时钟,实时解码需要25MHz时钟。最后,本文介绍了音频一致性测试的目的和必要性,并针对AVS音频标准,提出了AVS音频解码器需要测试的参数,以及一致性测试码流的生成方法。更多还原

【Abstract】 AVS audio standard is the third part of AVS (Audio and Video coding Standard), which is of our own independent intellectual property, it provides a good way to the field of high quality audio compression. And it applies to the high-resolution digital broadcast, high-density laser digital storage medium, wireless wide-band multimedia communication, broad band internet streaming media application and so on. There are many advanced technology on audio coding in AVS audio standard. It has great significance on the spread and applications of AVS audio standard to do the research on the algorithms and realization in real time of AVS audio coding.The thesis introduces the development and the fundamental principle of audio coding technology. The standard modules of AVS audio and the algorithm of each module are studied and analyzed. It could be found that the computational complexity of AVS audio coding is very high when transient signals are processed. Thus, two new methods are presented in place of the original method. It is proved by experimentation based on AVS that the audio quality of new methods is the same as the quality of the original method. But the computational complexity of AVS audio encoder and decoder are greatly decreased in the new methods.After the analysis of the algorithms of AVS audio, the thesis optimizes all modules of AVS audio so as to decrease the computational complexity of encoder and decoder greatly. After that, the porting and optimization of AVS audio encoder is presented based on DM642 EVM, including audio capturing, encoding, and bit stream transmitting in real time. And the porting and optimization of AVS audio decoder is presented based on DSK5416, including bit stream receiving, decoding and playing in real time. The encoder can encode the audio samples in real time with the sampling rate of 44.1kHz at 150MHz cycles while the decoder at 25MHz cycles.Finally, the thesis introduces the purpose and necessity of audio conformance testing and sums up the parameters that are necessary to be tested. And the method to generating bit streams which are used to test decoder is given at last.更多还原