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;

}