GraphicsCapture.dll marshall error

[rruann]

Hi rob, thank you for sharing with us this sample, very helpful I'm studying it to learn more about screen capturing using DirectX.

I have compiled the project source on Windows 10 19045.5073, using VS22 17.12.4, Radeon RX 7600 XT (drivers updated) but I'm getting these errors whenever I try to capture any window:

GraphicsCapture.dll!00007FFA693E7FFB: ReturnHr(1) tid(8a94) 8001010E The application called an interface that was marshalled for a different thread.
    Msg:[winrt::hresult_error: The application called an interface that was marshalled for a different thread.] 
C:\Users\RUAN\Desktop\Win32CaptureSample-main\Win32CaptureSample\x64\Debug\Generated Files\winrt\Windows.Graphics.Capture.h(54)\Win32CaptureSample.exe!00007FF678AFBA5B: LogHr(1) tid(8a94) 8001010E The application called an interface that was marshalled for a different thread.
    [auto __cdecl winrt::impl::consume_Windows_Graphics_Capture_IDirect3D11CaptureFramePool<struct winrt::Windows::Graphics::Capture::IDirect3D11CaptureFramePool>::Recreate(const struct winrt::Windows::Graphics::DirectX::Direct3D11::IDirect3DDevice &,const enum winrt::Windows::Graphics::DirectX::DirectXPixelFormat &,int,const struct winrt::Windows::Graphics::SizeInt32 &) const]
Win32CaptureSample.exe!00007FF678C55040: ReturnHr(1) tid(8a94) 8001010E The application called an interface that was marshalled for a different thread.
    Msg:[winrt::hresult_error: The application called an interface that was marshalled for a different thread.] 
GraphicsCapture.dll!00007FFA693E7B24: ReturnHr(2) tid(8a94) 8001010E The application called an interface that was marshalled for a different thread.
    Msg:[winrt::hresult_error: The application called an interface that was marshalled for a different thread.] 

At the moment I'm using BitBlt to capture a specific window (960x540) compress the image and send it through a websocket server, I'm taking one frame/image every 100ms which result in something like 10fps, i'm doing it like this:

// ...

BITMAPINFO bi;
data->bi.bmiHeader.biSize        = sizeof(BITMAPINFOHEADER);
data->bi.bmiHeader.biWidth       = data->width;
data->bi.bmiHeader.biHeight      = -data->height;
data->bi.bmiHeader.biPlanes      = 1;
data->bi.bmiHeader.biBitCount    = 24;
data->bi.bmiHeader.biCompression = BI_RGB;

data->hdcWindow = GetDCEx(hwnd, 0, DCX_WINDOW | DCX_CACHE);
data->hdcMemDC = CreateCompatibleDC(data->hdcWindow);
data->hbm = CreateDIBSection(data->hdcMemDC, &data->bi, DIB_RGB_COLORS, (void**)&data->Scan0, 0, 0);
SelectObject(data->hdcMemDC, data->hbm);

// ...

void capture() {
    BitBlt(data->hdcMemDC, 0, 0, data->width, data->height, data->hdcWindow, 0, 0, SRCCOPY);
}

I'm capturing 200~ windows, BitBlt is using so much GPU;
I'm reading that using DirectX is more efficient.

Using the Windows.Graphics.Capture API is it possible to take one capture every 100ms instead of a live stream?
Would it use less GPU than BitBlt in this specific use case?

[robmikh]

Do you see the same issue with this commit?
0c07c6a

Windows.Graphics.Capture will be a bit more efficient, but at the end of the day you're capturing a fairly large number of windows and pulling the pixels back into system memory. I would advise doing as much as you can on the GPU (e.g. changing color depth, resizing, hardware accelerated encoding) and only copy to system memory at the end.