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use v4l2 overlay in qt application

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  • M Offline
    M Offline
    MajidKamali
    wrote on last edited by
    #1

    Hi.
    I have a raspberry pi 3 B+ with qt 5.12.4 installed on it.
    I want to use camera v1 module in qt.
    v4l2 is installed and v4l2-ctl --overlay=1 shows camera output with awesome quality and frame rate.
    Is there a way to use this overlay in Qt (preferably QML)? e.g. access shared memory or use opengl etc.
    I want to call v4l2-ctl via QProcess and show live camera in my application. If you have a better alternative, I'm listening :)

    Thanks

    jsulmJ 1 Reply Last reply
    1
    • M MajidKamali

      Hi.
      I have a raspberry pi 3 B+ with qt 5.12.4 installed on it.
      I want to use camera v1 module in qt.
      v4l2 is installed and v4l2-ctl --overlay=1 shows camera output with awesome quality and frame rate.
      Is there a way to use this overlay in Qt (preferably QML)? e.g. access shared memory or use opengl etc.
      I want to call v4l2-ctl via QProcess and show live camera in my application. If you have a better alternative, I'm listening :)

      Thanks

      jsulmJ Offline
      jsulmJ Offline
      jsulm
      Lifetime Qt Champion
      wrote on last edited by
      #2

      @majidkamali Why not using https://doc.qt.io/qt-5/qcameraviewfinder.html instead of starting another process?

      https://forum.qt.io/topic/113070/qt-code-of-conduct

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      • M Offline
        M Offline
        MajidKamali
        wrote on last edited by
        #3

        @jsulm Camera does not work at all :-(
        I created a simple widget program and copy code from QCameraViewfinder doc.
        shows defaultServiceProvider::requestService(): no service found for - "org.qt-project.qt.camera" in console output :-(

        jsulmJ 1 Reply Last reply
        0
        • M MajidKamali

          @jsulm Camera does not work at all :-(
          I created a simple widget program and copy code from QCameraViewfinder doc.
          shows defaultServiceProvider::requestService(): no service found for - "org.qt-project.qt.camera" in console output :-(

          jsulmJ Offline
          jsulmJ Offline
          jsulm
          Lifetime Qt Champion
          wrote on last edited by
          #4

          @majidkamali I think you need GStreamer and its plugins for QCamera

          https://forum.qt.io/topic/113070/qt-code-of-conduct

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          • M Offline
            M Offline
            MajidKamali
            wrote on last edited by
            #5

            all gstreamer plugins are installed via apt-get in raspberry pi
            good, bad, ugly, qt plugin
            Do I need to recompile Qt to recognize gstreamer? I am using a manually compiled Qt 5.12.4 (in /opt/Qt5.12), but system has Qt 5.11 via apt-get

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            • SGaistS Offline
              SGaistS Offline
              SGaist
              Lifetime Qt Champion
              wrote on last edited by
              #6

              Hi,

              Did you also install the GStreamer development packages ?

              Otherwise your build is likely missing the related plugins.

              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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              • M Offline
                M Offline
                MajidKamali
                wrote on last edited by
                #7

                Did you also install the GStreamer development packages ?

                Yes I did. from apt-get

                Otherwise your build is likely missing the related plugins.

                How can I figure it out? I did not add any multimedia related option in configure script for configuring compiled Qt 5.12.4. (no skip option used)

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                • SGaistS Offline
                  SGaistS Offline
                  SGaist
                  Lifetime Qt Champion
                  wrote on last edited by
                  #8

                  You can check the content of the plugins folder of your custom Qt installation.

                  The detection is done when configure is run. If you added the development packages after having run configure, it won't detect it.

                  The tests logs will also contain these information.

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

                  1 Reply Last reply
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