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文章介绍了一种嵌入式可变速率宽带语音和音频编解码器ITU-T G.718。G.718编解码器能在8 kbit/s~32 kbit/s的可变速率上对16 kHz采样的语音和音频信号进行编解码。G.718编解码器具有5层结构,当高一层的码流被丢弃时不会影响到低一层码流的解码。核心层编码采用基于信号分类的CELP编码,L2层通过增加基音的贡献以及增加代数码本的方式对核心层的编码误差进行编码,L3、L4、L5层编码时,每个编码层对低一层编码的加权误差信号采用MDCT变换编码。测试了G.718编码器的WB-PESQ得分情况,结果表明,在相同速率下,G.718算法的性能优于G.729.1。
This article introduces ITU-T G.718, an embedded variable-rate wideband speech and audio codec. The G.718 codec encodes and decodes 16 kHz sampled speech and audio at a variable rate of 8 kbit / s to 32 kbit / s. G.718 codec has a 5-layer structure, when a layer of code stream is discarded will not affect the decoding of a layer of code stream. The core layer coding uses CELP coding based on signal classification. The L2 layer codes the coding error of the core layer by increasing the contribution of pitch and adding the algebraic codebook. When coding layers L3, L4 and L5, each coding layer pair is lower by one The weighted error signal of layer coding is encoded using MDCT transform. The WB-PESQ score of the G.718 encoder is tested. The results show that the G.718 algorithm outperforms G.729.1 at the same rate.