2345.c

语音信号800Hz 19点FIR低通滤波C语言浮点程序

#include <stdio.h>
const  int length = 180	/*语音帧长为180点＝22.5ms@8kHz采样*/
void  filter(int xin[ ],int xout[ ],int n,float h[ ]); /*滤波子程序说明*/
/*19点滤波器系数*/
static  float h[19]=
	{0.01218354,-0.009012882,-0.02881839,-0.04743239,-0.04584568,
-0.008692503,0.06446265,0.1544655,0.2289794,0.257883,
0.2289794,0.1544655,0.06446265,-0.008692503,-0.04584568,
-0.04743239,-0.02881839,-0.009012882,0.01218354};
static  int x1[length+20];
/*低通滤波浮点子程序*/
void  filter(int xin[ ],int xout[ ],int n,float h[ ])
{
int i,j;
float sum;
for(i=0;i<length;i++) x1[n+i-1]=xin[i];
for (i=0;i<length;i++)
{
sum=0.0;
for(j=0;j<n;j++) sum+=h[j]*x1[i-j+n-1];
xout[i]=(int)sum;
	}
for(i=0;i<(n-1);i++) x1[n-i-2]=xin[length-1-i];
}

/*主程序*/
void  main( )
{
FILE    *fp1,*fp2;
int     frame,indata[length],outdata[length];
fp1=fopen(insp.dat,"rb");		/*输入语音文件*/
fp2=fopen(outsp.dat,"wb");		/*滤波后语音文件*/

frame=0;
while(feof(fp1)==0)
{
frame++;
printf("frame=%d\n",frame);
for(i=0;i<length;i++)  indata[i]=getw(fp1); 	/*取一帧语音数据*/
filter(indata,outdata,19,h);		/*调用低通滤波子程序*/
for(i=0;i<length;i++)  putw(outdata[i],fp2);   	/*将滤波后的样值写入文件*/
}
fcloseall( );			/*关闭文件*/
return(0);