winapi - MFCreateAudioRenderer所需的带有Guid 1082E6C2-7660-4945-8E78-228A3B3329F6的怪异属性

Question

我正在尝试通过设置属性指针集调用MFCreateAudioRenderer来创建具有给定GUID的音频渲染器的实例。我已经设置了所有必需的值，但是调用返回E_INVALIDARG和mftrace.exe显示

13808,33E0 15:09:52.27643 CMFAttributesDetours::GetUnknown @014C4550 - enter
13808,33E0 15:09:52.27644 CMFAttributesDetours::GetUnknown @014C4550 attribute not found guidKey = {1082E6C2-7660-4945-8E78-228A3B3329F6}
13808,33E0 15:09:52.27644 CMFAttributesDetours::GetUnknown @014C4550 - exit (failed hr=0xC00D36E6 MF_E_ATTRIBUTENOTFOUND)

我在任何地方都找不到此GUID，也不知道要设置什么。有什么建议吗？

最少可复制的样本:

#include <atlbase.h>
#include <atlcom.h>

#include <Mfidl.h>
#include <Mfapi.h>
#include <Mmdeviceapi.h>
#include <string>
#include <vector>
#include <map>
#include <Functiondiscoverykeys_devpkey.h>
#include <Audioclient.h>
#include <Codecapi.h>
#include <Audiopolicy.h>

#pragma comment(lib, "Mfplat.lib")
#pragma comment(lib, "Mf.lib")

int main(int argc, char** argv)
{
    CoInitializeEx(nullptr, COINIT_MULTITHREADED);
    CComPtr<IMMDeviceEnumerator> pMMDeviceEnumerator;
    pMMDeviceEnumerator.CoCreateInstance(__uuidof(MMDeviceEnumerator));
    std::map<std::wstring, CComPtr<IMMDevice>> Devices;
    if (pMMDeviceEnumerator)
    {
        CComPtr<IMMDeviceCollection> pMMDeviceCollection;
        if (SUCCEEDED(pMMDeviceEnumerator->EnumAudioEndpoints(EDataFlow::eRender, DEVICE_STATE_ACTIVE, &pMMDeviceCollection)))
        {
            UINT nDeviceCount = 0;
            if (SUCCEEDED(pMMDeviceCollection->GetCount(&nDeviceCount)))
            {
                UINT nDeviceIndex = 0;
                while (nDeviceIndex < nDeviceCount)
                {
                    CComPtr<IMMDevice> pMMDevice;
                    if (SUCCEEDED(pMMDeviceCollection->Item(nDeviceIndex, &pMMDevice)))
                    {
                        CComPtr<IPropertyStore> pPropertyStore;
                        if (SUCCEEDED(pMMDevice->OpenPropertyStore(STGM_READ, &pPropertyStore)))
                        {
                            PROPVARIANT Variant;
                            PropVariantInit(&Variant);
                            if (SUCCEEDED(pPropertyStore->GetValue(PKEY_Device_FriendlyName, &Variant)))
                            {
                                wchar_t* pId = nullptr;
                                if (SUCCEEDED(pMMDevice->GetId(&pId)))
                                {
                                    Devices.emplace(pId, pMMDevice);
                                    CoTaskMemFree(pId);
                                }
                            }
                        }
                    }
                    ++nDeviceIndex;
                }
            }
        }
    }
    std::vector<CComPtr<IMFMediaSink>> MediaSinks;
    for (const auto& Device : Devices)
    {
        CComPtr<IMFAttributes> pAttributes;
        MFCreateAttributes(&pAttributes, 0);
        CComPtr<IMFMediaSink> pAudioRenderer;
        HRESULT hResult = pAttributes->SetString(MF_AUDIO_RENDERER_ATTRIBUTE_ENDPOINT_ID, Device.first.c_str());
        hResult = pAttributes->SetUINT32(MF_AUDIO_RENDERER_ATTRIBUTE_ENDPOINT_ROLE, ERole::eMultimedia);
        hResult = pAttributes->SetUINT32(MF_AUDIO_RENDERER_ATTRIBUTE_STREAM_CATEGORY, AUDIO_STREAM_CATEGORY::AudioCategory_BackgroundCapableMedia);
        hResult = pAttributes->SetUINT32(MF_AUDIO_RENDERER_ATTRIBUTE_FLAGS, 0);
        hResult = pAttributes->SetGUID(MF_AUDIO_RENDERER_ATTRIBUTE_SESSION_ID, GUID_NULL);
        hResult = MFCreateAudioRenderer(pAttributes, &pAudioRenderer);
        if (SUCCEEDED(hResult))
        {
            MediaSinks.push_back(pAudioRenderer);
        }
    }
    CoUninitialize();
}

Answer 1

相关的MSDN bit是:

...If you specify a device role, the SAR uses whatever audio device has been assigned for that role. To specify the device role, set the MF_AUDIO_RENDERER_ATTRIBUTE_ENDPOINT_ROLE attribute.

您通过ID或ROLE标识设备，两者是互斥的，因此，当您一次提供两者时，它们就是 E_INVALIDARG。