AcquireNextFrame not working (Desktop Duplication API & D3D11) - c++

Question

I've put together this code that takes a screenshot of the desktop and maps it for raw pixel data access, but the output is all zeros. I have no idea what i've done wrong. After looking at many examples of the Desktop Duplication Api online I don't see any differences between them and mine.
This is my method to initialize everything, and no errors are raised.
BOOL init()
{
CHECKHR(D3D11CreateDevice(nullptr, D3D_DRIVER_TYPE_HARDWARE, nullptr, 0, gFeatureLevels, gNumFeatureLevels, D3D11_SDK_VERSION, &lDevice, &FeatureLevel, &lImmediateContext))
IDXGIDevice* lDxgiDevice;
CHECKHR(lDevice->QueryInterface(IID_PPV_ARGS(&lDxgiDevice)))
IDXGIAdapter* lDxgiAdapter;
CHECKHR(lDxgiDevice->GetParent(__uuidof(IDXGIAdapter), (void**)&lDxgiAdapter))
lDxgiDevice->Release();
IDXGIOutput* lDxgiOutput;
CHECKHR(lDxgiAdapter->EnumOutputs(0, &lDxgiOutput))
lDxgiAdapter->Release();
CHECKHR(lDxgiOutput->GetDesc(&OutputDesc))
IDXGIOutput1* lDxgiOutput1;
CHECKHR(lDxgiOutput->QueryInterface(IID_PPV_ARGS(&lDxgiOutput1)))
lDxgiOutput->Release();
CHECKHR(lDxgiOutput1->DuplicateOutput(lDevice, &lDeskDupl))
lDxgiOutput1->Release();
lDeskDupl->GetDesc(&OutputDuplDesc);
D3D11_TEXTURE2D_DESC desc;
desc.Width = OutputDuplDesc.ModeDesc.Width;
desc.Height = OutputDuplDesc.ModeDesc.Height;
desc.Format = OutputDuplDesc.ModeDesc.Format;
desc.ArraySize = 1;
desc.BindFlags = 0;
desc.MiscFlags = 0;
desc.SampleDesc.Count = 1;
desc.SampleDesc.Quality = 0;
desc.MipLevels = 1;
desc.CPUAccessFlags = D3D11_CPU_ACCESS_READ | D3D11_CPU_ACCESS_WRITE;
desc.Usage = D3D11_USAGE_STAGING;
CHECKHR(lDevice->CreateTexture2D(&desc, NULL, &lDestImage))
return TRUE;
}
the CHECKHR macro i'm using was tested by me and works, just to clarify that it is not the problem.
This is the code that I use to actually grab the frame:
int main()
{
init();
HRESULT hr;
IDXGIResource* lDesktopResource;
ID3D11Texture2D* lAcquiredDesktopImage;
DXGI_OUTDUPL_FRAME_INFO FrameInfo;
while (true)
{
if (SUCCEEDED(lDeskDupl->AcquireNextFrame(INFINITE, &FrameInfo, &lDesktopResource)))
{
break;
}
}
hr = lDesktopResource->QueryInterface(IID_PPV_ARGS(&lAcquiredDesktopImage));
if (FAILED(hr))
{
cout << "QueryInterface failed!" << endl;
system("pause");
}
lDesktopResource->Release();
lImmediateContext->CopyResource(lDestImage, lAcquiredDesktopImage);
lAcquiredDesktopImage->Release();
lDeskDupl->ReleaseFrame();
D3D11_MAPPED_SUBRESOURCE resource;
UINT subresource = D3D11CalcSubresource(0, 0, 0);
hr = lImmediateContext->Map(lDestImage, subresource, D3D11_MAP_READ_WRITE, 0, &resource);
if (FAILED(hr))
{
cout << "Map failed!" << endl;
system("pause");
}
BYTE* pb = (BYTE*)(resource.pData);
for (int i = 0; i < 2000000; i++)
{
cout << (int)pb[i] << endl;
}
system("pause");
return 0;
}
All that happens is 2000000 zeros get printed to the console. Is there something i'm missing or that I cant see?

Answer 1

First, call D3D11CreateDevice against specific adapter which output you are about to duplicate:
BOOL init()
{
IDXGIFactory* lDxgiFactory;
CHECKHR(CreateDXGIFactory1(__uuidof(IDXGIFactory), (void**)&lDxgiFactory))
IDXGIAdapter* lDxgiAdapter;
CHECKHR(lDxgiFactory->EnumAdapters(0, &lDxgiAdapter))
lDxgiFactory->Release();
CHECKHR(D3D11CreateDevice(lDxgiAdapter, D3D_DRIVER_TYPE_UNKNOWN, nullptr, 0, gFeatureLevels, gNumFeatureLevels, D3D11_SDK_VERSION, &lDevice, &FeatureLevel, &lImmediateContext))
IDXGIDevice* lDxgiDevice;
CHECKHR(lDevice->QueryInterface(IID_PPV_ARGS(&lDxgiDevice)))
//IDXGIAdapter* lDxgiAdapter;
//CHECKHR(lDxgiDevice->GetParent(__uuidof(IDXGIAdapter), (void**)&lDxgiAdapter))
lDxgiDevice->Release();
IDXGIOutput* lDxgiOutput;
CHECKHR(lDxgiAdapter->EnumOutputs(0, &lDxgiOutput))
lDxgiAdapter->Release();
CHECKHR(lDxgiOutput->GetDesc(&OutputDesc))
IDXGIOutput1* lDxgiOutput1;
CHECKHR(lDxgiOutput->QueryInterface(IID_PPV_ARGS(&lDxgiOutput1)))
lDxgiOutput->Release();
CHECKHR(lDxgiOutput1->DuplicateOutput(lDevice, &lDeskDupl))
// ...
Then, your code is not quite accurate around AcquireNextFrame. You need to wait for actual frame and do ReleaseFrame in the loop while you are skipping.
// ...
while (true)
{
if (SUCCEEDED(lDeskDupl->AcquireNextFrame(INFINITE, &FrameInfo, &lDesktopResource)) && FrameInfo.LastPresentTime.QuadPart)
{
break;
}
lDeskDupl->ReleaseFrame();
}
// ...