ffmpeg - Getting green screen in ffplay: Streaming desktop (DirectX surface) as H264 video over RTP stream using Live555

Question

I'm trying to stream the desktop(DirectX surface in NV12 format) as H264 video over RTP stream using Live555 & Windows media foundation's hardware encoder on Windows10, and expecting it to be rendered by ffplay (ffmpeg 4.2). But only getting a green screen like below,

I referred MFWebCamToRTP mediafoundation-sample & Encoding DirectX surface using hardware MFT for implementing live555's FramedSource and changing the input source to DirectX surface instead of webCam.

Here is an excerpt of my implementation for Live555's doGetNextFrame callback to feed input samples from directX surface:

virtual void doGetNextFrame()
{
    if (!_isInitialised)
    {
        if (!initialise()) {
            printf("Video device initialisation failed, stopping.");
            return;
        }
        else {
            _isInitialised = true;
        }
    }

    //if (!isCurrentlyAwaitingData()) return;

    DWORD processOutputStatus = 0;
    HRESULT mftProcessOutput = S_OK;
    MFT_OUTPUT_STREAM_INFO StreamInfo;
    IMFMediaBuffer *pBuffer = NULL;
    IMFSample *mftOutSample = NULL;
    DWORD mftOutFlags;
    bool frameSent = false;
    bool bTimeout = false;

    // Create sample
    CComPtr<IMFSample> videoSample = NULL;

    // Create buffer
    CComPtr<IMFMediaBuffer> inputBuffer;
    // Get next event
    CComPtr<IMFMediaEvent> event;
    HRESULT hr = eventGen->GetEvent(0, &event);
    CHECK_HR(hr, "Failed to get next event");

    MediaEventType eventType;
    hr = event->GetType(&eventType);
    CHECK_HR(hr, "Failed to get event type");


    switch (eventType)
    {
    case METransformNeedInput:
        {
            hr = MFCreateDXGISurfaceBuffer(__uuidof(ID3D11Texture2D), surface, 0, FALSE, &inputBuffer);
            CHECK_HR(hr, "Failed to create IMFMediaBuffer");

            hr = MFCreateSample(&videoSample);
            CHECK_HR(hr, "Failed to create IMFSample");
            hr = videoSample->AddBuffer(inputBuffer);
            CHECK_HR(hr, "Failed to add buffer to IMFSample");

            if (videoSample)
            {
                _frameCount++;

                CHECK_HR(videoSample->SetSampleTime(mTimeStamp), "Error setting the video sample time.
");
                CHECK_HR(videoSample->SetSampleDuration(VIDEO_FRAME_DURATION), "Error getting video sample duration.
");

                // Pass the video sample to the H.264 transform.

                hr = _pTransform->ProcessInput(inputStreamID, videoSample, 0);
                CHECK_HR(hr, "The resampler H264 ProcessInput call failed.
");

                mTimeStamp += VIDEO_FRAME_DURATION;
            }
        }

        break;

    case METransformHaveOutput:

        {
            CHECK_HR(_pTransform->GetOutputStatus(&mftOutFlags), "H264 MFT GetOutputStatus failed.
");

            if (mftOutFlags == MFT_OUTPUT_STATUS_SAMPLE_READY)
            {
                MFT_OUTPUT_DATA_BUFFER _outputDataBuffer;
                memset(&_outputDataBuffer, 0, sizeof _outputDataBuffer);
                _outputDataBuffer.dwStreamID = outputStreamID;
                _outputDataBuffer.dwStatus = 0;
                _outputDataBuffer.pEvents = NULL;
                _outputDataBuffer.pSample = nullptr;

                mftProcessOutput = _pTransform->ProcessOutput(0, 1, &_outputDataBuffer, &processOutputStatus);

                if (mftProcessOutput != MF_E_TRANSFORM_NEED_MORE_INPUT)
                {
                    if (_outputDataBuffer.pSample) {

                        //CHECK_HR(_outputDataBuffer.pSample->SetSampleTime(mTimeStamp), "Error setting MFT sample time.
");
                        //CHECK_HR(_outputDataBuffer.pSample->SetSampleDuration(VIDEO_FRAME_DURATION), "Error setting MFT sample duration.
");

                        IMFMediaBuffer *buf = NULL;
                        DWORD bufLength;
                        CHECK_HR(_outputDataBuffer.pSample->ConvertToContiguousBuffer(&buf), "ConvertToContiguousBuffer failed.
");
                        CHECK_HR(buf->GetCurrentLength(&bufLength), "Get buffer length failed.
");
                        BYTE * rawBuffer = NULL;

                        fFrameSize = bufLength;
                        fDurationInMicroseconds = 0;
                        gettimeofday(&fPresentationTime, NULL);

                        buf->Lock(&rawBuffer, NULL, NULL);
                        memmove(fTo, rawBuffer, fFrameSize);

                        FramedSource::afterGetting(this);

                        buf->Unlock();
                        SafeRelease(&buf);

                        frameSent = true;
                        _lastSendAt = GetTickCount();

                        _outputDataBuffer.pSample->Release();
                    }

                    if (_outputDataBuffer.pEvents)
                        _outputDataBuffer.pEvents->Release();
                }

                //SafeRelease(&pBuffer);
                //SafeRelease(&mftOutSample);

                break;
            }
        }

        break;
    }

    if (!frameSent)
    {
        envir().taskScheduler().triggerEvent(eventTriggerId, this);
    }

    return;

done:

    printf("MediaFoundationH264LiveSource doGetNextFrame failed.
");
    envir().taskScheduler().triggerEvent(eventTriggerId, this);
}

Initialise method:

bool initialise()
{
    HRESULT hr;
    D3D11_TEXTURE2D_DESC desc = { 0 };

    HDESK CurrentDesktop = nullptr;
    CurrentDesktop = OpenInputDesktop(0, FALSE, GENERIC_ALL);
    if (!CurrentDesktop)
    {
        // We do not have access to the desktop so request a retry
        return false;
    }

    // Attach desktop to this thread
    bool DesktopAttached = SetThreadDesktop(CurrentDesktop) != 0;
    CloseDesktop(CurrentDesktop);
    CurrentDesktop = nullptr;
    if (!DesktopAttached)
    {
        printf("SetThreadDesktop failed
");
    }

    UINT32 activateCount = 0;

    // h264 output
    MFT_REGISTER_TYPE_INFO info = { MFMediaType_Video, MFVideoFormat_H264 };

    UINT32 flags =
        MFT_ENUM_FLAG_HARDWARE |
        MFT_ENUM_FLAG_SORTANDFILTER;

    // ------------------------------------------------------------------------
    // Initialize D3D11
    // ------------------------------------------------------------------------

    // Driver types supported
    D3D_DRIVER_TYPE DriverTypes[] =
    {
        D3D_DRIVER_TYPE_HARDWARE,
        D3D_DRIVER_TYPE_WARP,
        D3D_DRIVER_TYPE_REFERENCE,
    };
    UINT NumDriverTypes = ARRAYSIZE(DriverTypes);

    // Feature levels supported
    D3D_FEATURE_LEVEL FeatureLevels[] =
    {
        D3D_FEATURE_LEVEL_11_0,
        D3D_FEATURE_LEVEL_10_1,
        D3D_FEATURE_LEVEL_10_0,
        D3D_FEATURE_LEVEL_9_1
    };
    UINT NumFeatureLevels = ARRAYSIZE(FeatureLevels);

    D3D_FEATURE_LEVEL FeatureLevel;

    // Create device
    for (UINT DriverTypeIndex = 0; DriverTypeIndex < NumDriverTypes; ++DriverTypeIndex)
    {
        hr = D3D11CreateDevice(nullptr, DriverTypes[DriverTypeIndex], nullptr,
            D3D11_CREATE_DEVICE_VIDEO_SUPPORT,
            FeatureLevels, NumFeatureLevels, D3D11_SDK_VERSION, &device, &FeatureLevel, &context);
        if (SUCCEEDED(hr))
        {
            // Device creation success, no need to loop anymore
            break;
        }
    }

    CHECK_HR(hr, "Failed to create device");

    // Create device manager
    UINT resetToken;
    hr = MFCreateDXGIDeviceManager(&resetToken, &deviceManager);
    CHECK_HR(hr, "Failed to create DXGIDeviceManager");

    hr = deviceManager->ResetDevice(device, resetToken);
    CHECK_HR(hr, "Failed to assign D3D device to device manager");


    // ------------------------------------------------------------------------
    // Create surface
    // ------------------------------------------------------------------------
    desc.Format = DXGI_FORMAT_NV12;
    desc.Width = surfaceWidth;
    desc.Height = surfaceHeight;
    desc.MipLevels = 1;
    desc.ArraySize = 1;
    desc.SampleDesc.Count = 1;

    hr = device->CreateTexture2D(&desc, NULL, &surface);
    CHECK_HR(hr, "Could not create surface");

    hr = MFTEnumEx(
        MFT_CATEGORY_VIDEO_ENCODER,
        flags,
        NULL,
        &info,
        &activateRaw,
        &activateCount
    );
    CHECK_HR(hr, "Failed to enumerate MFTs");

    CHECK(activateCount, "No MFTs found");

    // Choose the first available encoder
    activate = activateRaw[0];

    for (UINT32 i = 0; i < activateCount; i++)
        activateRaw[i]->Release();

    // Activate
    hr = activate->ActivateObject(IID_PPV_ARGS(&_pTransform));
    CHECK_HR(hr, "Failed to activate MFT");

    // Get attributes
    hr = _pTransform->GetAttributes(&attributes);
    CHECK_HR(hr, "Failed to get MFT attributes");

    // Unlock the transform for async use and get event generator
    hr = attributes->SetUINT32(MF_TRANSFORM_ASYNC_UNLOCK, TRUE);
    CHECK_HR(hr, "Failed to unlock MFT");

    eventGen = _pTransform;
    CHECK(eventGen, "Failed to QI for event generator");

    // Get stream IDs (expect 1 input and 1 output stream)
    hr = _pTransform->GetStreamIDs(1, &inputStreamID, 1, &outputStreamID);
    if (hr == E_NOTIMPL)
    {
        inputStreamID = 0;
        outputStreamID = 0;
        hr = S_OK;
    }
    CHECK_HR(hr, "Failed to get stream IDs");

     // ------------------------------------------------------------------------
    // Configure hardware encoder MFT
   // ------------------------------------------------------------------------
    CHECK_HR(_pTransform->ProcessMessage(MFT_MESSAGE_SET_D3D_MANAGER, reinterpret_cast<ULONG_PTR>(deviceManager.p)), "Failed to set device manager.
");

    // Set low latency hint
    hr = attributes->SetUINT32(MF_LOW_LATENCY, TRUE);
    CHECK_HR(hr, "Failed to set MF_LOW_LATENCY");

    hr = MFCreateMediaType(&outputType);
    CHECK_HR(hr, "Failed to create media type");

    hr = outputType->SetGUID(MF_MT_MAJOR_TYPE, MFMediaType_Video);
    CHECK_HR(hr, "Failed to set MF_MT_MAJOR_TYPE on H264 output media type");

    hr = outputType->SetGUID(MF_MT_SUBTYPE, MFVideoFormat_H264);
    CHECK_HR(hr, "Failed to set MF_MT_SUBTYPE on H264 output media type");

    hr = outputType->SetUINT32(MF_MT_AVG_BITRATE, TARGET_AVERAGE_BIT_RATE);
    CHECK_HR(hr, "Failed to set average bit rate on H264 output media type");

    hr = MFSetAttributeSize(outputType, MF_MT_FRAME_SIZE, desc.Width, desc.Height);
    CHECK_HR(hr, "Failed to set frame size on H264 MFT out type");

    hr = MFSetAttributeR

Answer 1

It’s harder than it seems.

If you want to use the encoder as you’re doing, by calling IMFTransform interface directly, you have to convert RGB frames to NV12. If you want good performance, you should do it on GPU. Possible to do with pixel shaders, render 2 frames, full size one into DXGI_FORMAT_R8_UNORM render target with brightness, half-size into DXGI_FORMAT_R8G8_UNORM target with color, and write two pixel shaders to produce NV12 values. Both render targets can render into 2 planes of the same NV12 texture, but only since Windows 8.

Other method is use sink writer. It can host multiple MFTs at the same time so you can supply RGB textures in VRAM, the sink writer will first convert them into NV12 with one MFT (that's likely to be proprietary hardware one implemented by GPU driver, just like the encoder), then pass to encoder MFT. It’s relatively easy to encode into an mp4 file, use MFCreateSinkWriterFromURL API to create the writer. It’s much harder to get raw samples out of the sink writer however, you have to implement a custom media sink, custom stream sink for it’s video stream, and call MFCreateSinkWriterFromMediaSink to create the writer.

There’s more.

Regardless on the encoding methods, you can’t reuse frame textures. Each frame you get from DD, you should create a new texture and pass it to MF.

Video encoders expect constant frame rate. DD doesn’t give you that, it gives you a frame every time something changes on the screen. Can be 144 FPS if you have a gaming monitor, can be 2 FPS if the only change is blinking cursor. Ideally, you should submit frames to MF at constant frame rate, specified in your video media type.

If you want to stream to network, more often than not you have to also supply parameter sets. Unless you’re using Intel hardware h265 encoder which is broken with no comments from Intel, MF gives you that data in MF_MT_MPEG_SEQUENCE_HEADER attribute of media type, by calling SetCurrentMediaType on IMFMediaTypeHandler interface. You can implement that interface to get notified. You’ll only get that data after you start encoding. That's if you use a sink writer, for IMFTransform method it's easier, you should get MF_E_TRANSFORM_STREAM_CHANGE code from ProcessOutput method, then call GetOutputAvailableType to get the updated media type with that magic blob.