Function audio_init

StereoKitC/systems/audio.cpp:349–423

///////////////////////////////////////////

bool audio_init() {
	au_mix_temp = sk_malloc_t(float, au_mix_temp_size);
	memset(au_mix_temp, 0, sizeof(float) * au_mix_temp_size);

	if (ma_context_init(nullptr, 0, nullptr, &au_context) != MA_SUCCESS) {
		return false;
	}

#if defined(_MSC_VER)
	if (au_default_device_out_id.wasapi[0] == '\0') {
		HRESULT hr = isac_activate(_countof(au_active_sounds), isac_data_callback);

		if (SUCCEEDED(hr)) {
			log_info("Using audio backend: ISAC");
			return true;
		} else if (hr == E_NOT_VALID_STATE) {
			log_diag("ISAC audio backend not available, falling back to miniaudio! It's likely the device doesn't have Windows Sonic enabled, which can be found under Settings->Sound->Device Properties->Spatial Sound.");
		} else {
			log_warnf("ISAC audio backend failed 0x%X, falling back to miniaudio!", hr);
		}
	}
#endif

	au_config = ma_device_config_init(ma_device_type_playback);
	au_config.playback.format   = AU_SAMPLE_FORMAT;
	au_config.playback.channels = 2;
	au_config.sampleRate        = AU_SAMPLE_RATE;
	au_config.dataCallback      = data_callback;
	au_config.pUserData         = nullptr;

	// If we've requested a specific output device, like Oculus requires,
	// we set that up here.
#if defined(SK_OS_WINDOWS) || defined(SK_OS_WINDOWS_UWP)
	if (au_default_device_out_id.wasapi[0] != '\0') {
		au_config.playback.pDeviceID = &au_default_device_out_id;
	}
#endif

	ma_result result = ma_device_init(&au_context, &au_config, &au_device);
	if (result != MA_SUCCESS) {
		log_warnf("Failed to open audio playback device, '%s'.", ma_result_description(result));
		
		// Make a desperate attempt to fall back to a null device.
		ma_backend backend = ma_backend_null;
		if (ma_context_init(&backend, 1, nullptr, &au_context) != MA_SUCCESS) {
			return false;
		}
		result = ma_device_init(&au_context, &au_config, &au_device);
		
		// Even the null device failed, so let's stop.
		if (result != MA_SUCCESS) {
			log_errf("Failed to open null audio playback device, '%s'.", ma_result_description(result));
			return false;
		}
	}

	result = ma_device_start(&au_device);
	if (result != MA_SUCCESS) {