Warped Filter

频率规整滤波器(Warped Filter)具有非线性的频率标度，通过合适的设计可以使其标度逼近ERB或Bark等符合人耳听觉特性的标度，因此在音频和语音信号处理中得到广泛的应用。WFIR滤波器的结构比FIR滤波器复杂，因此其运算耗时要比FIR多。

 

Warped linear predictive coding

http://en.wikipedia.org/wiki/Warped_linear_predictive_coding

 

Warped linear predictive coding (warped LPC or WLPC) is a variant of linear predictive coding in which the spectral representation of the system is modified, for example by replacing the unit delays used in an LPC implementation with first-order allpass filters. This can have advantages in reducing the bitrate required for a given level of perceived audio quality/intelligibility, especially in wideband audio coding.

 

Warped LPC was first proposed in 1980 by Hans Werner Strube.

 

Warped Filter 就是 一个filter加一个一阶全通滤波器

Warped DCT  就是 一个DCT加一个一阶全通滤波器

Warped FFT   就是 一个FFT加一个 一阶全通滤波器

 

以Warped DCT为例

而这个全通滤波一般如下面状况

 

 

再以Warped Filter为例

Warped 参数

Warped filter

Warped 对filter的影响