randtowav.c

#include <stdio.h>
#include <stdint.h>
char wav_data[] = {
   'R', 'I', 'F', 'F',
    0,   0,   0,   0,
   'W', 'A', 'V', 'E',
   'f', 'm', 't', ' ',
    16,  0,   0,   0, /*subchunk1size*/
    1,   0,           /*audio format*/
    1,   0,           /*num channels*/
    68,  172, 0,   0, /*sample rate 44100*/
    136, 88,  1,   0, /*byte rate 88200*/
    2,   0,           /*block align*/
    16,  0,           /*bits per sample*/
   'd', 'a', 't', 'a',/*subchunk2id*/
    0,   0,   0,   0  /*subchunk2size*/



};

int main(){
   int numsamples;
   uint32_t length;
   uint32_t subchunk2size;
   FILE *fp = fopen("rand.wav", "wb");
   if (!fp) {perror("rand.wav"); return 1;}
   fwrite(wav_data, sizeof(wav_data), 1, fp);
   int16_t buff;
   while (1){
           fread(&buff, sizeof(int16_t), 1, stdin);
           if (feof(stdin)) break;
           fwrite(&buff, sizeof(int16_t), 1, fp);
           numsamples++;
   }
   length = (uint32_t)ftell(fp)-(uint32_t)8;
   fseek(fp, 4, SEEK_SET);
   fwrite(&length, sizeof(uint32_t), 1, fp);

   subchunk2size = numsamples*2;
   fseek(fp, 40, SEEK_SET);
   fwrite(&subchunk2size, sizeof(uint32_t), 1, fp);

   fclose(fp);
   return 0;
}