How to find audio devices that are connected

Question

I'm trying to find the audio devices (both input and output) connected to my computer. I would like to switch my default audio out from headphones to speakers and back.

The docs feel cyclical, telling me I need to use IMMDeviceCollection to enumerate my devices, but to get the collection, I need to provide it to the IMMDevicenumerator, but it can't be empty otherwise it throws an error/warning.

The short, how do I list my audio devices? How can I switch what is considered my default audio endpoint?

TIA

void AudioControl::getDevices()
{
	IMMDeviceEnumerator* deviceEnumerator = NULL;
	IMMDeviceCollection* deviceCollection = NULL;

	HRESULT hr = CoInitialize(NULL);
	if (SUCCEEDED(hr))
	{
		std::cout << "Initialized" << std::endl;
		hr = CoCreateInstance(__uuidof(MMDeviceEnumerator), NULL, CLSCTX_ALL, __uuidof(IMMDeviceEnumerator), (void**)&deviceEnumerator);
		if (SUCCEEDED(hr))
		{
			std::cout << "Created instance" << std::endl;
			hr = deviceEnumerator->EnumAudioEndpoints(eRender, DEVICE_STATE_ACTIVE, (IMMDeviceCollection**)deviceCollection);
			if (SUCCEEDED(hr))
			{
				if (deviceCollection != NULL)
				{
					std::cout << "Enumerated devices" << std::endl;
					std::wcout << "Devices: " << deviceCollection << std::endl;
					std::wcout << "Type: " << typeid(deviceCollection).name() << std::endl;
				}
			}
			std::cout << "Done enumerating devices" << std::endl;
		}
	}
	deviceCollection->Release();
	deviceEnumerator->Release();
	CoUninitialize();

}

Answer 1

Hello,

Welcome to Microsoft Q&A!

IMMDeviceEnumerator::EnumAudioEndpoints method returns a IMMDeviceCollection interface which represents a collection of multimedia device resources. The code example prints the display names of all audio-rendering endpoint devices in the system. Also see the example.

To set default audio endpoint, see the example(IPolicyConfig).

Thank you.

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Answer 2

The posted code contains an error --

This line -

hr = deviceEnumerator->EnumAudioEndpoints(eRender, DEVICE_STATE_ACTIVE, (IMMDeviceCollection**)deviceCollection);

should be

hr = deviceEnumerator->EnumAudioEndpoints(eRender, DEVICE_STATE_ACTIVE, &deviceCollection);