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QScreenCapture and X11 virtual framebuffer

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  • R Offline
    R Offline
    RobertB
    wrote on 7 Apr 2025, 13:28 last edited by RobertB 4 Aug 2025, 02:10
    #1

    Exotic question time :D

    On X11, Xvfb is a tool you can use to start a virtual framebuffer. Within this new display, you can run applications.

    sudo xvfb-run --listen-tcp --server-num 99 -s "-nocursor -ac -screen 0 1280x720x24" firefox -kiosk "https://qt.io"

    Then, for example, with ffmpeg you could record this by pointing it to DISPLAY 99:

    ffmpeg -y -f pulse -framerate 30 -f x11grab -video_size 1280x720 -draw_mouse 0 -i :99 -pix_fmt yuv420p -vcodec libx264 -crf 24 -acodec aac -b:a 128k -movflags +faststart test.mp4

    My question is, can we use QScreenCapture to capture DISPLAY 99?

    I know QScreenCapture uses QScreen to capture from, but from a quick glance at the documentation, I could not determine how to do the equivalent of ffmpeg's 'x11grab'.

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    • S Offline
      S Offline
      SGaist
      Lifetime Qt Champion
      wrote on 7 Apr 2025, 17:52 last edited by
      #2

      Hi,

      Interesting one !
      As is, I don't think so, at least from an "external application" recording point of view.
      I think it should work if the application is started on the virtual frame buffer.

      Interested in AI ? www.idiap.ch
      Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

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      7 Apr 2025, 13:28

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