QtNdiMonitorCapture

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Qt6 based app that simulates NDI Tools' Studio Monitor and Screen Capture.

• NDI's Studio Monitor is a NDI Receiver + Viewer.
• NDI's Screen Capture is a Monitor Capture + NDI Sender.

QtNdiMonitorCapture does them both, so it can actually monitor its own output! :)
(Studio Monitor can also send NDI video output, but even if you were able to have it view its own output then you would probably just be viewing a black screen.)
NOTE: It is interesting to run Monitor mode to view its own Monitor Capture screen in full-screen and see the result of the lossy data transfer. If P216 pixel format was used to capture->transmit->receive->render then I suspect that would be much less lossy (I wonder how close to lossless).

Limitations

• Currently only compiles and runs on Windows.
  Sorry! Feel free to help compile and test and implement on other platforms!
• Missing features (not exhaustive):
  • Studio Monitor
    • Recording: Very low priority to me.
    • KVM: I tried to get this to work but the NDI KVM API keeps crashing whenever it is called. :/
      Another problem is that this requires NDI Advanced SDK, which may have an incompatible license.
    • Settings ...
      • Application ...
      • Audio ...
      • Video ...
      • Overlay ...
      • Output ...
      • PTZ Settings ...: Very low priority to me.
  • Screen Capture
    • Audio: Again, sorry, but this initial **Screen** Capture proof of concept was focused literally on the screen/video only;
      Audio is [sort of] simpler to capture & send than video, but the UX is more complicated to select which of the multiple audio input and output devices to capture from.
      I will get to this eventually, but it is lower priority proof of concept for now.
    • Frame Rate ...
    • Capture Settings ...
    • Audio Source ...
    • Webcam Video Source ... : Very low priority to me.
    • Webcam Audio Source ... : Very low priority to me.
    • Enable KVM Control: I tried to get this to work but the NDI KVM API keeps crashing whenever it is called. :/

Feel free to help add missing features or support for other platforms.
See #TODO.

Usage

Launch the app and right click on the view window to get a context menu showing all of the currently availble NDI Sources and select an NDI Source to view.

Monitor Capture Start will show a System Tray Icon that you can use to later stop the capture.

The app will not close while a capture is running.

To close the app while a capture is running either:

1. first stop the capture and then close the app. -or-
2. Right-click on the main window or the system tray icon and select Exit.

Command line options

Launch in Monitor mode (the default):

QtNdiMonitorCapture.exe
-or-
QtNdiMonitorCapture.exe --mode=monitor

Launch in Capture mode:

QtNdiMonitorCapture.exe --mode=capture

More are planned.

Build

Requirements:

• Currently only compiles and runs on Windows
• Visual Studio 2019 Community installed
• Qt6 installed with the following components:
  • MSVC 2019 64-bit
  • Qt Multimedia
  • Qt Creator 9.0.2
  • Qt Installer Framework 4.5
• NDI Advanced SDK to be installed.
  I could have just required the non-Advanced SDK, but I hope to one day add KVM support, which requires the Advanced SDK.

Steps:

Qt Creator 9.0.2 IDE

1. Launch Qt Creator
2. Open the QtNdiMonitorCapture.pro file
3. Build and Run

PowerShell 7.3.3 Command-Line

1. $env:Qt6_DIR = 'C:\Qt\6.4.2\msvc2019_64\'
2. CI\windows-build.ps1 "CONFIG+=package"

TODO

Please help to whittle down this list!:

• Check for memory leaks and fix any found, especially when:
  1. Stopping and starting Capture.
  2. Stopping and starting when switching between different NDI Sources.
• Add support for any platform that Qt6 supports, especially:
  1. Raspberry Pi OS
  2. Jetson Nano Linux4Tegra
  3. Linux
  4. MacOS
• Confirm and/or improve hardware acceleration options.
• Confirm the app compiles and creates a distribution for all supported platforms.
• Confirm the app launches on all supported platforms.
• Confirm Monitor mode works on all supported platforms.
• Implement Capture mode for all supported platforms.
• Confirm multiple monitors works on all supported platforms.
• Find a way to capture from more than one monitor...or all! :)
• Add command-line to list NDI Sources and exit.
• Add command-line to start viewing a specific NDI Source.
• Add command-line to start capturing a specific Monitor (or Monitors).
• Successfully port from QMake to CMake.
• Add all of the Limitations of missing NDI Studio Monitor and Screen Capture features, including NDI|HX3 support. NDI|HX requires NDI Advanced SDK which may have an incompatible license. :/
• Add support for sending to and receiving from NDI Groups.
• Improve Capture performance, including adding Game Capture option [similar to OBS].
• Improve Monitor performance.
• Audit the code for all uses of pass-by-pointer (*) vs pass-by-reference (&) and decide the best one to use for each situation.
  For performance tuning, this should usually be the fastest one.
  I have worked in the Managed world too long and was a little lazy writing the code. :/
  Some Qt classes I even pass without either * or &, and I suspect that results in a copy operation that probably isn't very efficient. :)

NOTES:

• Capture does try to use a double-buffering technique, but there is still some noticable sheering. :/
• Monitor code uses 100% Qt6 classes and should be very portable to any platform that Qt6 supports.
  It would be exceptionally nice to implement a cross-platform P216 pixel format! :)
• Capture code is [currently] Windows specific and could use a cross-platform abstraction, probably using OBS Studio as inspiration. https://github.com/obsproject/obs-studio/blob/master/libobs/obs-video.c

References

Monitor Capture is based off of WinRT sample code from:

• https://github.com/microsoft/Windows.UI.Composition-Win32-Samples/tree/master/cpp/ScreenCaptureforHWND
• https://github.com/peilinok/Windows.UI.Composition-Win32-Samples/tree/master/cpp/ScreenCaptureforHWND
• https://github.com/robmikh/Win32CaptureSample I've made a few tweaks of my own, but you can still compare them with:

OBS Studio and OBS-NDI:

• https://github.com/obsproject/obs-studio

  • https://github.com/obsproject/obs-studio/tree/master/plugins/win-capture
  • https://github.com/obsproject/obs-studio/blob/master/libobs-winrt/winrt-capture.h
  • https://github.com/obsproject/obs-studio/blob/master/libobs-winrt/winrt-capture.cpp
  • Display Capture:
    • https://github.com/obsproject/obs-studio/blob/master/plugins/win-capture/dc-capture.h
    • https://github.com/obsproject/obs-studio/blob/master/plugins/win-capture/dc-capture.c
  • Game Capture:
    • https://github.com/obsproject/obs-studio/blob/master/plugins/win-capture/game-capture.c
  • Monitor Capture:
    • https://github.com/obsproject/obs-studio/blob/master/plugins/win-capture/monitor-capture.c
  • Window Capture:
    • https://github.com/obsproject/obs-studio/blob/master/plugins/win-capture/window-capture.c

• https://github.com/Palakis/obs-ndi

Safe Queue:

• https://stackoverflow.com/a/16075550/252308

Other Inspirations:

• https://git.lpgs.io/GPG/gptv-ndi-recorder
• https://orfast.com
• https://dicaffeine.com
• https://github.com/melnijir/Dicaffeine
• https://github.com/melnijir/libyuri_ndi_module/tree/master/src/modules/ndi
• https://github.com/jleben/ndi-tools
• https://github.com/smilingthax/xndiview
• https://github.com/Gargaj/Bonzomatic