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QtMultimedia backend setup

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  • R Offline
    R Offline
    Rotty
    wrote on 5 Oct 2024, 10:08 last edited by
    #1

    Hi,
    I need to write multivideo player. I tried python+tkinter+tkvideoplayer. This failed to play smoothly fullhd video in fullscreen on raspberry 5. I switch to pyqt and the basic test failed with message:

    No QtMultimedia backends found. Only QMediaDevices, QAudioDevice, QSoundEffect, QAudioSink, and QAudioSource are available.
    Failed to initialize QMediaPlayer "Not available"
    Failed to create QVideoSink "Not available"
    

    So, I installed Qt using official install script and run Media player from examples. It end with the same error. No QtMultimedia backend.

    My question: How to set/install any QtMultimedia backend on freshly installed 64bit official rasbian?

    J 1 Reply Last reply 5 Oct 2024, 11:07
    0
    • R Rotty
      5 Oct 2024, 10:08

      Hi,
      I need to write multivideo player. I tried python+tkinter+tkvideoplayer. This failed to play smoothly fullhd video in fullscreen on raspberry 5. I switch to pyqt and the basic test failed with message:

      No QtMultimedia backends found. Only QMediaDevices, QAudioDevice, QSoundEffect, QAudioSink, and QAudioSource are available.
      Failed to initialize QMediaPlayer "Not available"
      Failed to create QVideoSink "Not available"
      

      So, I installed Qt using official install script and run Media player from examples. It end with the same error. No QtMultimedia backend.

      My question: How to set/install any QtMultimedia backend on freshly installed 64bit official rasbian?

      J Offline
      J Offline
      JonB
      wrote on 5 Oct 2024, 11:07 last edited by
      #2

      @Rotty
      Because of https://stackoverflow.com/questions/78577031/pyqt6-6-7-0-how-to-fix-error-no-qtmultimedia-backends-found please start by stating the exact version of PyQt you are running.

      R 1 Reply Last reply 5 Oct 2024, 11:52
      0
      • J JonB
        5 Oct 2024, 11:07

        @Rotty
        Because of https://stackoverflow.com/questions/78577031/pyqt6-6-7-0-how-to-fix-error-no-qtmultimedia-backends-found please start by stating the exact version of PyQt you are running.

        R Offline
        R Offline
        Rotty
        wrote on 5 Oct 2024, 11:52 last edited by Rotty 10 May 2024, 11:52
        #3

        @JonB No version of PyQt now. I'm switched to C++ and Qt 6.7.3. I have installed it using qt-online-installer-linux-arm64-4.8.1.run from Qt web page. I have ran Qt creator then and tried Media Player example in C++.

        1 Reply Last reply
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        • S Offline
          S Offline
          SGaist
          Lifetime Qt Champion
          wrote on 5 Oct 2024, 14:16 last edited by
          #4

          Hi,

          Start your application with the QT_DEBUG_PLUGINS environment variable set to 1. It will print a lot of information and should tell you more about what is failing with the backend.

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

          R 1 Reply Last reply 5 Oct 2024, 17:14
          0
          • S SGaist
            5 Oct 2024, 14:16

            Hi,

            Start your application with the QT_DEBUG_PLUGINS environment variable set to 1. It will print a lot of information and should tell you more about what is failing with the backend.

            R Offline
            R Offline
            Rotty
            wrote on 5 Oct 2024, 17:14 last edited by
            #5

            @SGaist said in QtMultimedia backend setup:

            QT_DEBUG_PLUGINS

            Thank You, I one step closer to solution. It looks like missing library.

            qt.core.library: "/home/aosp/Qt/6.7.3/gcc_arm64/plugins/multimedia/libffmpegmediaplugin.so" cannot load: Cannot load library /home/aosp/Qt/6.7.3/gcc_arm64/plugins/multimedia/libffmpegmediaplugin.so: libavformat.so.58: cannot open shared object file: No such file or directory
            qt.core.plugin.loader: QLibraryPrivate::loadPlugin failed on "/home/aosp/Qt/6.7.3/gcc_arm64/plugins/multimedia/libffmpegmediaplugin.so" : "Cannot load library /home/aosp/Qt/6.7.3/gcc_arm64/plugins/multimedia/libffmpegmediaplugin.so: libavformat.so.58: cannot open shared object file: No such file or directory"
            No QtMultimedia backends found. Only QMediaDevices, QAudioDevice, QSoundEffect, QAudioSink, and QAudioSource are available.
            qt.core.plugin.loader: Found metadata in lib /home/aosp/Qt/6.7.3/gcc_arm64/qml/QtQml/WorkerScript/libworkerscriptplugin.so, metadata=
            {
                "IID": "org.qt-project.Qt.QQmlEngineExtensionInterface",
                "archlevel": 0,
                "className": "QtQmlWorkerScriptPlugin",
                "debug": false,
                "uri": [
                    "QtQml.WorkerScript"
                ],
                "version": 395008
            }
            
            1 Reply Last reply
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            • R Offline
              R Offline
              Rotty
              wrote on 5 Oct 2024, 17:32 last edited by Rotty 10 May 2024, 17:47
              #6

              Quick update. liibavformat.so.58 is not available in current raspbian.

              The following packages have unmet dependencies:
               libavformat58 : Depends: libavcodec58 (= 8:4.3.6-0+deb11u1+rpt5)
                               Depends: libsrt1.4-gnutls (>= 1.4.2) but it is not installable
              

              Is there a way how to tell Qt to use version 59?

              Temporary solution:
              Switch multimedia backend: Set enviroment variable QT_MEDIA_BACKEND=gstreamer

              1 Reply Last reply
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              • S Offline
                S Offline
                SGaist
                Lifetime Qt Champion
                wrote on 5 Oct 2024, 18:43 last edited by
                #7

                One other option is to rebuild the ffmpeg backend (just it) with your system provided librairies.

                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
                0

                3/7

                5 Oct 2024, 11:52

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