openal beep with volume

beep.cpp

#include <AL/alut.h> // OpenAl
#include <cmath>
#include <iostream>
#include <thread>

using namespace std;

void init_al() {
	const char* defname = alcGetString(NULL, ALC_DEFAULT_DEVICE_SPECIFIER);
	ALCdevice* dev = alcOpenDevice(defname);
	ALCcontext* ctx = alcCreateContext(dev, NULL);
	alcMakeContextCurrent(ctx);
}

void exit_al() {
	ALCcontext* ctx = alcGetCurrentContext();
	ALCdevice* dev = alcGetContextsDevice(ctx);
	alcMakeContextCurrent(0);
	alcDestroyContext(ctx);
	alcCloseDevice(dev);
}

void Beep(float freq = 440, float volume = 1.0, float seconds = 0.5) {

	ALuint buf;
	alGenBuffers(1, &buf);

	unsigned sample_rate = 10000;
	size_t buf_size = seconds * sample_rate;
	short* samples = new short[buf_size];
	if (samples == 0) {
		cout << "It seems there is no more heap memory. Sorry we cannot make a beep!";
	}
	for (unsigned i = 0; i < buf_size; i++)
		samples[i] = volume * 32760 * sin(2 * M_PI * i * freq / sample_rate);

	alBufferData(buf, AL_FORMAT_MONO16, samples, buf_size, sample_rate);

	ALuint src;
	alGenSources(1, &src);
	alSourcei(src, AL_BUFFER, buf);
	alSourcePlay(src);
	alutSleep(seconds + 0.5);
	delete[] samples;

	alSourceStopv(1, &src);		// new line
	alDeleteSources(1, &src); // new line
	alDeleteBuffers(1, &buf); // new line
}

int main() {
	init_al();

	Beep(440, 1.0, 0.5);
	Beep(440, 0.8, 0.5);
	Beep(440, 0.6, 0.5);
	Beep(440, 0.4, 0.5);
	Beep(540, 0.2, 0.1);
	Beep(740, 1.0, 0.2);
	Beep(840, 1.0, 0.3);
	Beep(940, 1.0, 0.5);

	exit_al();
}