GetDefaultOutputDeviceID.cpp

#pragma once
#include "stdafx.h"
#include <cstdio>
#include <mmdeviceapi.h>
#include <Functiondiscoverykeys_devpkey.h>
#include <iostream>

const CLSID CLSID_MMDeviceEnumerators = __uuidof(MMDeviceEnumerator);
const IID IID_IMMDeviceEnumerators = __uuidof(IMMDeviceEnumerator);

constexpr auto REFTIMES_PER_SEC = (10000000 * 25);
constexpr auto REFTIMES_PER_MILLISEC = 10000;

#define EXIT_ON_ERROR(hres)  \
              if (FAILED(hres)) { goto Exit; }
#define SAFE_RELEASE(punk)  \
              if ((punk) != NULL)  \
                { (punk)->Release(); (punk) = NULL; }

static LPWSTR ListEndpoints();

static LPWSTR ListEndpoints()
{
    wchar_t targetName[] = L"CABLE Output (VB-Audio Virtual Cable)";
    LPWSTR targetID = NULL;
    HRESULT hr = S_OK;
    IMMDeviceEnumerator* pEnumerator = NULL;
    IMMDeviceCollection* pCollection = NULL;
    IMMDevice* pEndpoint = NULL;
    IPropertyStore* pProps = NULL;
    LPWSTR pwszID = NULL;

    hr = CoCreateInstance(CLSID_MMDeviceEnumerators, NULL, CLSCTX_ALL, IID_IMMDeviceEnumerators, (void**)&pEnumerator);
    EXIT_ON_ERROR(hr);

    hr = pEnumerator->EnumAudioEndpoints(eCapture, DEVICE_STATE_ACTIVE, &pCollection);
    EXIT_ON_ERROR(hr);

    UINT  count;
    hr = pCollection->GetCount(&count);
    EXIT_ON_ERROR(hr);

    if (count == 0)
    {
        printf("No endpoints found.\n");
    }

    // Each iteration prints the name of an endpoint device.
    PROPVARIANT varName;
    for (ULONG i = 0; i < count; i++)
    {
        // Get the pointer to endpoint number i.
        hr = pCollection->Item(i, &pEndpoint);
        EXIT_ON_ERROR(hr);

        // Get the endpoint ID string.
        hr = pEndpoint->GetId(&pwszID);
        EXIT_ON_ERROR(hr);

        hr = pEndpoint->OpenPropertyStore(
            STGM_READ, &pProps);
        EXIT_ON_ERROR(hr);

        // Initialize the container for property value.
        PropVariantInit(&varName);

        // Get the endpoint's friendly-name property.
        hr = pProps->GetValue(PKEY_Device_FriendlyName, &varName);
        EXIT_ON_ERROR(hr);

        // Print the endpoint friendly name and endpoint ID.
        //printf("Endpoint %d: \"%S\" (%S)\n", i, varName.pwszVal, pwszID);
        if (wcscmp(varName.pwszVal, targetName) == 0) {
            hr = pEndpoint->GetId(&targetID);
            EXIT_ON_ERROR(hr);
        }

        CoTaskMemFree(pwszID);
        pwszID = NULL;
        PropVariantClear(&varName);
    }

Exit:
    CoTaskMemFree(pwszID);
    pwszID = NULL;
    PropVariantClear(&varName);
    SAFE_RELEASE(pEnumerator);
    SAFE_RELEASE(pCollection);
    SAFE_RELEASE(pEndpoint);
    SAFE_RELEASE(pProps);
    return targetID;
}