Making the computer go beep boop.

beep-boop.c

#include "SDL.h"

#define SAMPLE_RATE 48000
#define CHANNELS 2
#define SAMPLES (SAMPLE_RATE*2)

int main (int argc, char** argv)
{
  SDL_Init(SDL_INIT_EVERYTHING);

  SDL_AudioSpec want, got;
  want.freq = SAMPLE_RATE;
  want.format = AUDIO_F32;
  want.channels = CHANNELS;
  want.samples = 4096;
  want.callback = NULL;

  float* buffer = calloc(SAMPLES * CHANNELS, sizeof *buffer);
  for (int i = 0; i < SAMPLE_RATE; i++) {
    float t = (float)i / (float)SAMPLE_RATE;
    float f = sin(t*648*3.14159f) * t*(1-t);
    float g = sin(t*432*3.14159f) * t*(1-t);
    buffer[i*2] = f;
    buffer[i*2+1] = f;
    buffer[SAMPLE_RATE*2 + i*2] = g;
    buffer[SAMPLE_RATE*2 + i*2 + 1] = g;
  }

  SDL_AudioDeviceID dev = SDL_OpenAudioDevice(NULL, 0, &want, &got, 0);
  if (dev == 0) {
    SDL_Log("Failed to open audio: %s", SDL_GetError());
  } else {
    SDL_QueueAudio(dev, buffer, SAMPLES * CHANNELS * sizeof *buffer);
    SDL_PauseAudioDevice(dev, 0);
    SDL_Delay(2200);
    SDL_CloseAudioDevice(dev);
  }
  SDL_Quit();
  return 0;
}