Old toy code to try out libopus with the 3D sound capabilities of OpenAL

Opustest.cpp

#include <iostream>
#include <memory>
#include <cmath>
#include <unistd.h>
#include <time.h>
#include <opus/opusfile.h>
#include <AL/al.h>
#include <AL/alc.h>

int main(int argc, const char *argv[])
{
	if(argc != 2)
	{
		std::cerr << "Usage: " << argv[0] << "file.opus\n";
		return EXIT_FAILURE;
	}

	auto file = op_open_file(argv[1], nullptr);
	if(!file)
	{
		std::cerr << "Could not open " << argv[1] << std::endl;
		return EXIT_FAILURE;
	}

	int channelCount = op_channel_count(file, -1);
	size_t pcm_buffersize = channelCount * op_pcm_total(file, -1);
	auto pcm_buffer = std::make_unique< int16_t[] >(pcm_buffersize);

	int16_t *i = pcm_buffer.get();
	while(i < pcm_buffer.get() + pcm_buffersize)
	{
		auto sampleCount = channelCount * op_read(file, i, pcm_buffersize - (i - pcm_buffer.get()), nullptr);
		if(sampleCount < 0)
			break;
		i += sampleCount;
	}

	// Downmix to mono
	size_t mono_buffersize = pcm_buffersize / channelCount;
	if(channelCount > 1)
	{
		for(size_t i = 0; i < mono_buffersize; ++i)
		{
			int32_t sum = 0;
			for(int j = 0; j < channelCount; ++j)
				sum += pcm_buffer[i * channelCount + j];
			pcm_buffer[i] = sum / channelCount;
		}
	}

	ALCdevice *device = alcOpenDevice(NULL);
	if(!device)
		return EXIT_FAILURE;
	ALCcontext *context = alcCreateContext(device, NULL);
	alcMakeContextCurrent(context);
	if(!context)
		return EXIT_FAILURE;

	ALuint al_buffer, al_source;
	alGenBuffers(1, &al_buffer);
	alGenSources(1, &al_source);

	alBufferData(al_buffer, AL_FORMAT_MONO16, pcm_buffer.get(), mono_buffersize * sizeof(int16_t), 48000);

	ALfloat sourcePos[] = {1.0, 0.0, 0.0};
	ALfloat sourceVel[] = {1.0, 0.0, 0.0};
	ALfloat listenerPos[] = {0.0, 0.0, 0.0};
	ALfloat listenerVel[] = {0.0, 0.0, 0.0};
	ALfloat listenerOri[] = {0.0, 0.0, -1.0, 0.0, 1.0, 0.0};

	alListenerfv(AL_POSITION, listenerPos);
	alListenerfv(AL_VELOCITY, listenerVel);
	alListenerfv(AL_ORIENTATION, listenerOri);

	alSourcei(al_source, AL_BUFFER, al_buffer);
	alSourcefv(al_source, AL_POSITION, sourcePos);
	alSourcefv(al_source, AL_VELOCITY, sourceVel);
	alSourcei(al_source, AL_LOOPING, AL_TRUE);

	alSourcePlay(al_source);

	struct timespec t0, tnow;
	clock_gettime(CLOCK_MONOTONIC, &t0);

	while(1)
	{
		clock_gettime(CLOCK_MONOTONIC, &tnow);
		float dt = tnow.tv_sec - t0.tv_sec + 1e-9 * (tnow.tv_nsec - t0.tv_nsec);
		float T = 1.0/3.0;
		float omega = T * 2 * M_PI * dt;
		sourcePos[0] = sourceVel[0] = cos(omega);
		sourcePos[1] = sourceVel[1] = sin(omega);
		alSourcefv(al_source, AL_POSITION, sourcePos);
		alSourcefv(al_source, AL_VELOCITY, sourceVel);
	}

	alDeleteSources(1, &al_source);
	alDeleteBuffers(1, &al_buffer);
	alcMakeContextCurrent(NULL);
	alcDestroyContext(context);
	alcCloseDevice(device);
	return 0;
}

/*
compile with (assuming Linux, gcc, libopus, libopusfile and OpenAL Soft):
g++ -I /usr/include/opus Opustest.cpp -lopus -lopusfile -lopenal
*/