G.718音频编码器核心层的一种低延时编码方案

语音编码器不仅要求提供高质量的语音,同时还要具有较低的编解码延时。较大的编码延时不仅会降低语音通信的服务质量,同时还可能减小系统容量。由于G.718编码器的延时主要由核心层算法引入,为了降低G.718编码器核心层的延时,提出了一种帧长为5ms的低延时编码方案,通过改变语音分类、开环基因搜索、线性预测系数的求解和量化方法,成功将编码延时在G.718基础上降低了25ms。主客观语音评测结果表明,该方案接近G.718核心层的重建语音质量。

A Low Delay Coding Scheme for the Core Layer of G.718 Audio Codec

A speech codec is supposed to provide high speech quality,as well as a low delay.Not only the service quality of voice communication is reduced,but also the system capacity could be reduced by the larger coding delay.Compared with the other speech codec standard,new embedded broadband voice is learned and audio codec standard ITU-T G.718 at present has lower voice decoding delay.Aiming at reducing the coding delay due to the core layer of G.718,a low delay coding scheme with 5-ms length of frame is proposed in the paper,which the delay is reduced by25 ms.Both the objective and subjective listening tests show that a near G.718 core layer reconstructed speech quality is achieved by using this scheme.