我想在C语言中做一个移动平均过滤器,我已经改编了一个正确工作的matlab程序,我的过滤器的输入是一个.pcm压缩文件(扫描音频信号),对我来说问题是C语言中移动平均值的输出存档,输出出错,信号只随时间减少(不填充)。以C语言移动平均值
低于我的C代码:
#include <stdio.h>
#include <stdlib.h>
#define m 16 // MEDIA LENGTH
int main()
{
short *x; // X VECTOR = 0
double coef[m]; // COEF VECTOR = 0
int i; // FOR COUNT VARIABLE
int n; // FOR COUNT VARIABLE
int itera; // LENGTH OF THE INPUT FILE
double aux; // AUX VARIABLE TO MAKE THE SUM
double *y; // AUX VECTOR TO RECEIVE X VECTOR
double *saida; // OUTPUT VECTOR
FILE *arq; // POINTER TO THE FILE
for (i = 0; i < m; i++) {
coef[i] = 1.0/m;
}
arq = fopen("sweep_100_3400.pcm", "rb");
if (arq == NULL)
{
printf("ERROR WHILE OPENING THE FILE\n");
return;
}
// compute size of file
fseek(arq,0,SEEK_END);
itera = ftell(arq)/sizeof(short);
rewind(arq);
// alloc mem for x, read the vector from input file
x = malloc(itera*sizeof(short));
fread(x,sizeof(short),itera,arq);
fclose(arq);
// alloc mem for y
y = malloc(itera*sizeof(double));
saida = malloc(itera*sizeof(double));
for (i=0; i < itera; i++) {
y[0] = x[i];
aux=0;
for (n=0; n<m; n++){
aux += coef[n] * y[n];
}
saida[i]=aux;
for (n=m; n <2; n--){
x[n] = x[n-1];
}
}
arq=fopen("saida_medial_movel_c.pcm","wb");
fwrite(saida, sizeof(double),itera,arq);
fclose(arq);
free(saida);
free(y);
free(x);
}
下面的图像是MATLAB程序的输出,以移动平均长度为16:
此图片在C语言中的输出移动平均长度为16:
有人知道可能是什么?
下面MATLAB中的代码,我已经适应:
%MOVING AVERAGE EXAMPLE SCRIPT
clear all;
close all;
clc;
% DEFINES MEDIA LENGTH
m = 16;
%VECTOS EQUAL ZERO
x = zeros (m,1);
coef = zeros (m,1);
%INITIALIZE VECTOR
for j = 1 : m,
coef (j,1) = 1/m;
end
%READ INPUT FILE
fid = fopen ('sweep_100_3400.pcm','rb');
s = fread (fid, 'int16');
fclose(fid);
subplot(2,1,1);
plot(s);
grid on;
title('ENTRADA DO FILTRO');
%PROCESS
itera = length(s);
sav_y = zeros (itera, 1);
%EXECUTE PROCESS
for j = 1 : itera,
x(1,1) = s (j,1);
%PRODUCTS SUM
y=0;
for n = 1 : m,
y = y + coef(n,1) * x(n,1);
end
sav_y(j,1) = y;
%SHIFT THE VECTOR
for n = m: -1 : 2,
x (n,1) = x(n-1,1);
end
end
%PLOT OUTPUT
subplot (2,1,2);
plot (sav_y);
grid on;
title('SAÍDA DO FLITRO');
%SAVE THE OUTPUT IN ANOTHER FILE
fid = fopen('saida_mm_manual.pcm','wb');
fwrite(fid,sav_y,'int16');
fclose(fid);
更新1(使用上面的答案):
信号的开头还是有干扰,但从中间到结束的信号是正确的。
开始使用自我解释的名称(在这里最好用英文发布)。像文件级别的'm'这样的单字符宏是一个禁止行为(无论如何都是小写字母)。然后将代码墙分成几个函数以获得更好的概述。最后调试代码。我们不是一个调试服务。看[问]! – Olaf
注意:'int main(){... return;'是个小问题。 – chux