I'm trying to re-write my software-only logic for displaying video feed from a web camera. This time using hardware and DirectX. (I need to preface this by saying that this is the first time that I'm writing something for DirectX.)

我正试图重写我的纯软件逻辑，以便显示来自网络摄像头的视频。这一次使用了硬件和DirectX。(在此之前，我需要说明的是，这是我第一次为DirectX编写代码。)

I have the following declared on the global scale:

我在全球范围内宣布了以下几点：

IMFMediaSource* g_pMediaSource = NULL;
ReaderCallback* gpRdrCallback = NULL;
IMFSourceReader* g_pSrcReader = NULL;

//DirectX stuff:
IDXGISwapChain1* g_pHW_SwapChain = NULL;               
ID3D11Device1* g_pHW_D3DDevice = NULL;                 
ID3D11DeviceContext1* g_pHW_ImmContext = NULL;         
IMFDXGIDeviceManager* g_pHW_DXGIDevMgr = NULL;         
ID3D11RenderTargetView* g_pHW_RenderTargetView = NULL; 
ID3D11Texture2D* g_pHW_BackBuffer = NULL;  

I get the IMFMediaSource for the webcam, using this code when the app starts:

我获取网络摄像头的IMFMediaSource，在应用程序启动时使用以下代码：

//Error handling is omitted for readability
CComPtr<IMFAttributes> com_attributes;
hr = MFCreateAttributes(&com_attributes, 2);

hr = com_attributes->SetGUID(MF_DEVSOURCE_ATTRIBUTE_SOURCE_TYPE,
                             MF_DEVSOURCE_ATTRIBUTE_SOURCE_TYPE_VIDCAP_GUID);

hr = com_attributes->SetString(MF_DEVSOURCE_ATTRIBUTE_SOURCE_TYPE_VIDCAP_SYMBOLIC_LINK, 
                               strWebcamSymLink.c_str());

CComPtr<IMFActivate> com_Activ;
hr = MFCreateDeviceSourceActivate(com_attributes, &com_Activ);

hr = com_Activ->ActivateObject(IID_PPV_ARGS(&g_pMediaSource));

Then I do the following (once) during initialization to set up DirectX:

然后，我在初始化期间执行以下操作(一次)来设置DirectX：

(Error handling is omitted for readability.)

(为提高可读性，省略了错误处理。)

//For this test, the input parameters are:
//(As they are received from a webcam)
//
//  szFrameW = 160;
//  szFrameH = 90;
//  nFrameRateNumer = 5;
//  nFrameRateDenom = 1;
//  nAspectRatioNumer = 1;
//  nAspectRatioDenom = 1;
//  dwIdxDev = 0;            //Webcam device index
//

DXGI_SWAP_CHAIN_DESC sd = {};

sd.BufferCount = 1;

sd.BufferDesc.Width = szFrameW;
sd.BufferDesc.Height = szFrameH;
sd.BufferDesc.Format = DXGI_FORMAT_R8G8B8A8_UNORM;
sd.BufferDesc.ScanlineOrdering = DXGI_MODE_SCANLINE_ORDER_PROGRESSIVE;
sd.BufferDesc.Scaling = DXGI_MODE_SCALING_CENTERED;
sd.BufferDesc.RefreshRate.Numerator = nFrameRateNumer;
sd.BufferDesc.RefreshRate.Denominator = nFrameRateDenom;

sd.BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT;

sd.OutputWindow = ghWnd;       //Main window handle
sd.Windowed = TRUE;

sd.SampleDesc.Count = 1;
sd.SampleDesc.Quality = 0;


D3D_FEATURE_LEVEL d3dFeatureLvls[] = {
    D3D_FEATURE_LEVEL_11_1,
};

UINT dwNumLvlsRequested = _countof(d3dFeatureLvls);

D3D_FEATURE_LEVEL FeatureLevelsSupported;

CComPtr<IDXGISwapChain> com_SwapChain;
CComPtr<ID3D11Device> com_Dev;
CComPtr<ID3D11DeviceContext> com_Ctx;

hr = D3D11CreateDeviceAndSwapChain(NULL, 
    D3D_DRIVER_TYPE_HARDWARE, 
    NULL, 
    D3D11_CREATE_DEVICE_BGRA_SUPPORT |
#ifdef _DEBUG
    D3D11_CREATE_DEVICE_DEBUG
#else
    0
#endif
    ,
    d3dFeatureLvls, 
    dwNumLvlsRequested, 
    D3D11_SDK_VERSION, 
    &sd, 
    &com_SwapChain, 
    &com_Dev, 
    &FeatureLevelsSupported,
    &com_Ctx);

//Get version 1.0 of interfaces - I'm not sure if I need it here?
hr = com_SwapChain.QueryInterface(&g_pHW_SwapChain);
hr = com_Dev.QueryInterface(&g_pHW_D3DDevice);
hr = com_Ctx.QueryInterface(&g_pHW_ImmContext);

hr = g_pHW_SwapChain->GetBuffer(0, IID_PPV_ARGS(&g_pHW_BackBuffer));

hr = g_pHW_D3DDevice->CreateRenderTargetView(g_pHW_BackBuffer, NULL, &g_pHW_RenderTargetView);

g_pHW_ImmContext->OMSetRenderTargets(1, &g_pHW_RenderTargetView, NULL);

D3D11_VIEWPORT vp;
vp.Width = (FLOAT)szFrameW;
vp.Height = (FLOAT)szFrameH;
vp.MinDepth = 0.0f;
vp.MaxDepth = 1.0f;
vp.TopLeftX = 0;
vp.TopLeftY = 0;

g_pHW_ImmContext->RSSetViewports( 1, &vp );

CComPtr<IMFTransform> com_Transform;
hr = g_pMediaSource->QueryInterface(IID_PPV_ARGS(&com_Transform));

UINT uiToken = 0;
hr = MFCreateDXGIDeviceManager(&uiToken, &g_pHW_DXGIDevMgr);

hr = g_pHW_DXGIDevMgr->ResetDevice(g_pHW_D3DDevice, uiToken);

hr = com_Transform->ProcessMessage(MFT_MESSAGE_SET_D3D_MANAGER, 
                                   (ULONG_PTR)g_pHW_DXGIDevMgr);

Then to initiate the Microsoft Media Foundation for asynchronous rendering from a webcam:

然后启动Microsoft Media Foundation以从网络摄像头进行异步渲染：

//Error handling is omitted for readability

hr = MFCreateAttributes(&com_attributes, 3);

gpRdrCallback = new ReaderCallback();
hr = com_attributes->SetUnknown(MF_SOURCE_READER_ASYNC_CALLBACK, gpRdrCallback);

hr = com_attributes->SetUINT32(MF_SOURCE_READER_ENABLE_ADVANCED_VIDEO_PROCESSING, TRUE);
hr = com_attributes->SetUINT32(MF_SOURCE_READER_DISCONNECT_MEDIASOURCE_ON_SHUTDOWN, TRUE);
hr = com_attributes->SetUnknown(MF_SOURCE_READER_D3D_MANAGER, g_pHW_DXGIDevMgr);

hr = MFCreateSourceReaderFromMediaSource(g_pMediaSource, com_attributes, &g_pSrcReader);

CComPtr<IMFMediaType> com_vid_output;
hr = MFCreateMediaType(&com_vid_output);

hr = com_vid_output->SetGUID(MF_MT_MAJOR_TYPE, MFMediaType_Video);
hr = com_vid_output->SetGUID(MF_MT_SUBTYPE, MFVideoFormat_RGB32);
hr = com_vid_output->SetUINT32(MF_MT_INTERLACE_MODE, MFVideoInterlace_Progressive);
hr = com_vid_output->SetUINT64(MF_MT_FRAME_SIZE, 
                               PackSize(szFrameW, szFrameH));

hr = com_vid_output->SetUINT64(MF_MT_FRAME_RATE, 
                               PackSize(nFrameRateNumer, nFrameRateDenom));

hr = MFSetAttributeRatio(com_vid_output,
    MF_MT_PIXEL_ASPECT_RATIO,
    nAspectRatioNumer,
    nAspectRatioDenom);

hr = g_pSrcReader->SetCurrentMediaType(dwIdxDev, NULL, com_vid_output);

//Initiate the read from a webcam (async)
hr = g_pSrcReader->SetStreamSelection(dwIdxDev, TRUE);
hr = g_pSrcReader->ReadSample(dwIdxDev,
                              0,
                              NULL, NULL, NULL, NULL);

After that from my ReaderCallback when a frame is read:

之后，当读取帧时，从我的ReaderCallback：

//Error handling is omitted for readability

HRESULT ReaderCallback::OnReadSample(HRESULT hrStatus, 
                                     DWORD dwStreamIndex,
                                     DWORD dwStreamFlags,
                                     LONGLONG llTimestamp,
                                     IMFSample* pSample)
{
    if(SUCCEEDED(hrStatus))
    {
        CComPtr<IMFMediaBuffer> com_buffer;
        hr = pSample->ConvertToContiguousBuffer(&com_buffer);

        com_buffer->AddRef();   /pseudo-call
        remember_video_buffer_for_later_processing(com_buffer);
        
    }

    //Initiate reading of another frame
    hr = g_pSrcReader->ReadSample(dwIdxDev,
                              0,
                              NULL, NULL, NULL, NULL);

    return S_OK;
}

Finally, when I am ready to render the video frame onto the window:
(The frame is received from my ReaderCallback::OnReadSample above.)

最后，当我准备好将视频帧呈现到窗口上时：(该帧是从上面的ReaderCallback：：OnReadSample接收的。)

//Error handling is omitted for readability

void renderFromRawVideoPixels(IMFMediaBuffer* pMediaBuffer)
{
    CComPtr<IMFDXGIBuffer> com_DxgBuffer;
    hr = pMediaBuffer->QueryInterface(IID_PPV_ARGS(&com_DxgBuffer));

    CComPtr<ID3D11Texture2D> com_Texture;
    hr = com_DxgBuffer->GetResource(IID_PPV_ARGS(&com_Texture));

    UINT nSubindex;
    hr = com_DxgBuffer->GetSubresourceIndex(&nSubindex);

    g_pHW_ImmContext->CopySubresourceRegion(g_pHW_BackBuffer,
        0, 0 ,0, 0,
        com_Texture,
        nSubindex,
        NULL);

    DXGI_PRESENT_PARAMETERS dpp = {};
    hr = g_pHW_SwapChain->Present1(0, 0, &dpp);
}

The call to g_pHW_ImmContext->CopySubresourceRegion above leaves the following error in the debugging output window and I get a black screen:

上面对g_phw_ImmContext->CopySubourceRegion的调用在调试输出窗口中留下了以下错误，并且我得到一个黑屏：

D3D11 ERROR: ID3D11DeviceContext::CopySubresourceRegion: Cannot invoke
CopySubresourceRegion when the Formats of each Resource are not the
same or at least castable to each other, unless one format is
compressed (DXGI_FORMAT_R9G9B9E5_SHAREDEXP, or
DXGI_FORMAT_BC[1,2,3,4,5,6,7]_* ) and the source format is similar to
the dest according to: BC[1|4] ~= R16G16B16A16|R32G32, BC[2|3|5|6|7]
~= R32G32B32A32, R9G9B9E5_SHAREDEXP ~= R32. [ RESOURCE_MANIPULATION
ERROR #281: COPYSUBRESOURCEREGION_INVALIDSOURCE]

I have no idea what it means.

我不知道这是什么意思。

Any help on how to resolve this?

任何帮助如何解决这个问题？

As the system tells you, the formats between what Media Foundation gives you back and what the DirectX swapchain expects are not compatible.

正如系统告诉您的那样，Media Foundation返回给您的内容和DirectX交换链期望的内容之间的格式不兼容。

You can make them compatible with two changes:

您可以使它们与两个更改兼容：

A) change the swapchain format, change this:

A)更改交换链格式，更改如下内容：

sd.BufferDesc.Format = DXGI_FORMAT_R8G8B8A8_UNORM;

into this:

进入这一阶段：

sd.BufferDesc.Format = DXGI_FORMAT_B8G8R8A8_UNORM;

B) change MF output video format, change this:

B)更改mf输出视频格式，更改如下：

hr = com_vid_output->SetGUID(MF_MT_SUBTYPE, MFVideoFormat_RGB32);
=> MF will give you back DXGI_FORMAT_B8G8R8X8_UNORM

into this:

进入这一阶段：

hr = com_vid_output->SetGUID(MF_MT_SUBTYPE, MFVideoFormat_ARGB32);
=> MF will give you back DXGI_FORMAT_B8G8R8A8_UNORM