XUserGetLocalId

HRESULT XUserGetLocalId(  
         XUserHandle user,  
         XUserLocalId* userLocalId  
)  

HRESULT GetAudioDeviceAssociation(
    IMMDeviceEnumerator* audioDeviceEnumerator,
    XUserLocalId user,
    XUserDefaultAudioEndpointKind defaultAudioEndpointKind,
    _Outptr_result_maybenull_ IMMDevice** endpoint)
{
    wchar_t audioDeviceId[XUserAudioEndpointMaxUtf16Count];
    RETURN_IF_FAILED_WITH_EXPECTED(XUserGetDefaultAudioEndpointUtf16(user, defaultAudioEndpointKind, std::size(audioDeviceId), audioDeviceId, nullptr), E_NOTFOUND);

    return audioDeviceEnumerator->GetDevice(audioDeviceId, endpoint);
}

HRESULT GetAudioAssociations()
{
    Mwrl::ComPtr<IMMDeviceEnumerator> audioDeviceEnumerator;

    RETURN_IF_FAILED(CoCreateInstance(
        __uuidof(MMDeviceEnumerator),
        nullptr,
        CLSCTX_ALL,
        __uuidof(IMMDeviceEnumerator),
        (void**)&audioDeviceEnumerator));

    XUserLocalId userLocalId;
    RETURN_IF_FAILED(XUserGetLocalId(_handle.get(), &userLocalId));

    {
        wil::unique_cotaskmem_string id;
        Mwrl::ComPtr<IMMDevice> device;
        if (SUCCEEDED(GetAudioDeviceAssociation(audioDeviceEnumerator.Get(), userLocalId, XUserDefaultAudioEndpointKind::CommunicationRender, &device)))
        {
            RETURN_IF_FAILED(device->GetId(&id));
        }
        appLog.AddLog("Preferred render communication device id: %S\n", id.get());
    }

    {
        wil::unique_cotaskmem_string id;
        Mwrl::ComPtr<IMMDevice> device;
        if (SUCCEEDED(GetAudioDeviceAssociation(audioDeviceEnumerator.Get(), userLocalId, XUserDefaultAudioEndpointKind::CommunicationCapture, &device)))
        {
            RETURN_IF_FAILED(device->GetId(&id));
        }
        appLog.AddLog("Preferred capture communication device id: %S\n", id.get());
    }

    return S_OK;
}