hpinput.c

Ilibc 语音编解码库算法。语音质量高。接口简单。

   
   /******************************************************************
   
       iLBC Speech Coder ANSI-C Source Code
   
       hpInput.c 
   
       Copyright (C) The Internet Society (2004). 
       All Rights Reserved.
   
   ******************************************************************/
   
   #include "constants.h"
   
   /*----------------------------------------------------------------*
    *  Input high-pass filter                          
    *---------------------------------------------------------------*/
   
   void hpInput( 
       float *In,  /* (i) vector to filter */
       int len,    /* (i) length of vector to filter */
       float *Out, /* (o) the resulting filtered vector */
       float *mem  /* (i/o) the filter state */
   ){
       int i;
       float *pi, *po;
   
       /* all-zero section*/
   
       pi = &In[0];
       po = &Out[0];
       for (i=0; i<len; i++) {
           *po = hpi_zero_coefsTbl[0] * (*pi);
           *po += hpi_zero_coefsTbl[1] * mem[0];
           *po += hpi_zero_coefsTbl[2] * mem[1];
   
           mem[1] = mem[0];
           mem[0] = *pi;
           po++;
   
   
           pi++;
   
       }
   
       /* all-pole section*/
   
       po = &Out[0];
       for (i=0; i<len; i++) {
           *po -= hpi_pole_coefsTbl[1] * mem[2];
           *po -= hpi_pole_coefsTbl[2] * mem[3];
   
           mem[3] = mem[2];
           mem[2] = *po;
           po++;
       }
   }