C言語で作る、はじめてのDAWソフト制作 | Codetter（こーどったー）

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#include <stdio.h>
#include <math.h>
int main(void)
{
    int i, j;
    unsigned char header[44] = {0x52, 0x49, 0x46, 0x46, 0x34, 0xb1, 0x02, 0x00, 0x57, 0x41, 0x56, 0x45, 0x66, 0x6d, 0x74, 0x20, 0x10, 0x00, 0x00, 0x00, 0x01, 0x00, 0x01, 0x00, 0x44, 0xac, 0x00, 0x00, 0x44, 0xac, 0x00, 0x00, 0x01, 0x00, 0x08, 0x00, 0x64, 0x61, 0x74, 0x61, 0x10, 0xb1, 0x02, 0x00};
    FILE *fp = fopen("out.wav", "wb");
    double x = 0.0f;
    double y = 0.0f;
    double z = 0.0f;
    unsigned char buff[44100/4] = {0};
    int p = 0;
    
    fwrite(header, 1, 44, fp);
    
    for(i=0; i<16; i++)
    {
        int key;
        scanf("%d", &key);
        for(j=0; j<44100/4; j++)
        {
            unsigned char a = ((unsigned char)((sin(x) >= 0.0 ? 1.0 : -1.0) * 64.0 + sin(z) * 63.0 + 128.0) + buff[p] * 3) / 4;
            buff[p] = a;
            p = (p + 1) % (44100 / 4);
            fwrite(&a, 1, 1, fp);
            x += (441.0 + sin(y) * 10.0) * pow(2.0, (double)key / 12.0) * 2.0 * 3.14159265358979 / 44100.0;
            y += 5.0 * 2.0 * 3.14159265358979 / 44100.0;
            z += (441.0 + sin(y) * 10.0) * pow(2.0, (double)(key + 7) / 12.0) * 2.0 * 3.14159265358979 / 44100.0;
        }
    }
    fclose(fp);
    return 0;
}
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