正弦变换编码的改进算法

Improved Sinusoidal Transform Coding Algorithm

提出了低码率正弦变换编码算法 (STC)的改进算法。为了准确地提取基音频率并尽量减少算法复杂度 ,改进算法采用了快速有效的混合基音提取方法以结合时、频域基音提取算法的优点。为保持谐波之间的相位信息 ,改进算法在解码端利用相邻帧的基音频率对谐波相位进行匹配跟踪 ,使重建语音保持了原始语音的特点。另外 ,改进算法在对幅度谱包络进行量化之前用双线性变换做了适合人耳听觉特性的预处理 ,降低了 L PC分析的阶数 。

A modified low bit rate sinusoidal transform coding algorithm(STC) is presented. A fast and accurate hybrid pitch detection algorithm is proposed, which combines the merits of both time domain and frequency domain methods. To keep up with the phase information between different harmonies, the improved algorithm utilizes fundamental frequency changes between sequential frames and performs harmony phase matching algorithm. Before the quantization of STFT envelope, the improved algorithm applies bilinear transform to frequency, resulting in the reshape of frequency axis according to physiological characteristics of human ear. We can thus achieve the goal of reducing the LPC order and further the reduction of bit rate.