kmixer_demo.c

//this program plays a sine wave at 440Hz for a second
#define SDL_MAIN_HANDLED
#include <kit_sdl2/kit_kmixer.h>

//#define PI2 (basically M_PI*2, which is already defined in macroconst.h)

#define sample_rate 44100
#define volume 0.5
#define hertz 440

float position = 0;
void sin_callback(void* userdata, void* _stream, int size, SDL_bool hasInput){
  float* destination = _stream;
  int len = size/sizeof(float);

  for(int i=0; i<len; ++i){
    destination[i] = SDL_sinf(position * PI2*hertz) * volume;
    position += 1.0f/sample_rate;
  }
}

int main(int argc, char** argv){
  //initialize kmixer and core, which kmixer relies on
  if(kit_coreInit(0)<0) return 1;
  if(kit_kmixerInit(-2)<0) return 2; //use only half the cpu cores present

  //set up device specification, which optionally doubles as voice 1's spec
  kit_kmixerVoiceSpec specO,spec={0};
  spec.callback = sin_callback;
  spec.freq     = sample_rate;
  spec.samples  = 1024;
  spec.stereo   = SDL_FALSE;
  spec.format   = AUDIO_F32;
  kit_kmixerDevice* device=kit_kmixerDeviceOpen(NULL,0,&spec,&specO);
  if(device==NULL) return 3;


  kit_kmixerDeviceUnpauseAndWait(device);
  SDL_Delay(1000); //let it play for 1 second
  kit_kmixerDevicePauseAndWait(device);


  kit_kmixerDeviceClose(&device);

  kit_kmixerQuit();
  kit_coreQuit();

  return 0;
}