论文标题:AMR声码器的研究和开发
Studies on Optimal Path Algorithms and Its Applications in Time-Varying and Stochastic Networks
论文作者 罗之丹
论文导师 张捷,论文学位 硕士,论文专业 通信与信息系统
论文单位 西北工业大学,点击次数 143,论文页数 63页File Size1952k
2002-03-01论文网 http://www.lw23.com/lunwen_18283027/ 声码器;语音编码标准;基音检测;动态平滑;语音激活检测
vocode;speech coding standardization;pitch-detect;dynamic smooth;voice activity detector
由于语音通信领域对高质量语音需求日益增加，语音编码技术也在近年来得到了飞速发展。AMR声码器是3GPP所提出的第三代移动通信语音编码标准，它实现语音的多种低速率编码和解码，支持静音抑制和舒适噪音生成，在MSC中发挥网关的作用，保证了基于ATM的第三代移动通信网与现有的网络资源PSTN/ISDN的互通性。由此，AMR声码器的研究和开发具有很大的实用价值。 本文首先研究了AMR声码器的算法，AMR声码器主要由多速率语音编码器、源控速率方案和错误消除机制三大部分组成。基于TI公司生产的DSPTMSC6000对其进行实现，结果表明语音质量达到了ITU的规定的标准，并严格通过了测试序列。 本文还介绍了基音检测常用的一些方法，并把AMR算法中基音检测模块提取出来，做了一定的研究。并且提出了一种简单高效的基音检测方法，采用时域自相关法和基音周期动态平滑相结合，消除大部分的半频和倍频的误判，取得了良好的效果。
With the continuously increasing of the demand of high quality of speech in telecommunication field, the technology of speech coding has been rapidly developed recently. AMR is the speech coding standardization of the 3G Mobile Communication submitted by 3GPP.lt achieves multi-rate speech coding and decoding, supports nonvoice restraining and comfort noise generation. It performs as the function of gateway in MSC, and it ensures the net of 3G mobile communication interworking with the existing net of PSTN and ISDN. So, The researching and developing of AMR is of great practical value.First the paper studies the algorithms of AMR speech coder. The AMR speech coder consists of the multi-rate speech coder, a source controlled rate scheme, and an error concealment mechanism. Based on the TMS320C6000 produced by Tl, we implement it. And its quality of the synthetic speech achieves the criterion prescribed by ITU, and it passes the test sequences strictly.The paper also introduces some general methods in pitch detected, and distills the module in the arithmetic of AMR coder for research. It also brings forward a simple and effective method, which adopts autocorrelation of time domain combining with dynamic smooth of pitch period. The method eliminates the errors of most half frequency and double, and reaches satisfactory effect.
|
