正弦函数如何变成声音

下面有一个例子，或以帮助大家更好的理解正弦函数如何变成声音，有兴趣的朋友可以把它拷到编译器中运行。它会生成一个44100采样，单声道、16位格式的PCM文件new.pcm，可以用cooledit进行播放！

#include <math.h>
#include <iostream>

#pragma warning(disable:4996)

#pragma warning(disable:4244)

using namespace std;

int _tmain(int argc, _TCHAR* argv[])

{

int sample_rate =
44100;

double step =
atan(1.0)*8/sample_rate; // 2*pi/44100

int sample_scale =
(int)pow(2.0,16-1); // 2^15

FILE *pFile =
fopen("new.pcm","wb");

double t = 0.0;

double sample;

// 生成10秒数据

for(int s = 0; s <
sample_rate*10; s++)

{

sample = 0;

//
sample = (sin(t) cos(20*t) sin(30*t)*cos(t*40)
sin(t*50) cos(t*600) sin(t*125) sin(t*87))/6;

double x = min(sin(t),cos(t));

double y = max(300 200*cos(t),300
200*sin(t));

double z = max(300 200*cos(t*1.5),300
200*sin(t*1.7));

sample =
(tan(t*2)*sin(x*y*600)*abs(sin(t/10))*abs(cos(t/5)))*0.2;

sample = abs(sin(t*10))*sin(x*y)*0.45;

sample = sin(sin(z*t*0.1))*0.15;

short nSample = sample*sample_scale;

fwrite(&nSample,1,2,pFile);

fflush(pFile);

//
printf("s=%d\n",s);

t = step;

}

fclose(pFile);

return 0;

}