Cannot find -lQt5Multimedia?!



  • Hi everyone
    i dont know what i installed or removed that this error came up!
    i even removed qtcreator and install it again, but still not works.
    please someone help me, its important and i dont know what to do.

    had another question too.
    i used QGraphicsVideoItem and QGraphicsScene to show videos in my app,
    some videos opens, but some of them not.
    it not based on the size of videos, i tested it and all the gstreamer packages installed on my os.
    since i cant open my app with qt right now, i cant put here the error!
    so if you know anything about this too, please help
    thanks a lot
    Ubuntu 14.04 x64



    1. I would recommend to install Qt from qt-project.org
      It comes with all libraries and qtcreator.

    2. Qt uses gstreamer0.10 Ubuntu-14.04 does not have gstreamer0.10 by default you need to install separately.
      If you need to find out why gstreamer does not work run your app with GST_DEBUG=N where N is a verbosity level. I would start from N = 3. See "here":http://gstreamer.freedesktop.org/data/doc/gstreamer/head/manual/html/section-checklist-debug.html for more info.



  • [quote author="andreyc" date="1414598450"]1. I would recommend to install Qt from qt-project.org
    It comes with all libraries and qtcreator.

    1. Qt uses gstreamer0.10 Ubuntu-14.04 does not have gstreamer0.10 by default you need to install separately.
      If you need to find out why gstreamer does not work run your app with GST_DEBUG=N where N is a verbosity level. I would start from N = 3. See "here":http://gstreamer.freedesktop.org/data/doc/gstreamer/head/manual/html/section-checklist-debug.html for more info.
      [/quote]
      thanks
      ill try 2. when the application fixed
      about the 1. , i downloaded qt-opensource-linux-x64-5.3.2.run and installed it. so i think it must has the libraries!
      if you meant something else, please say more
      thanks again


  • Yes, I meant exactly that.
    Do you have @QT += multimedia multimediawidgets@ in .pro file?
    And just for checking do you have
    @ Qt5.4.0/5.4/gcc_64/lib/libQt5Multimedia*@



  • yes, i add it to my project.
    about the second one, i have

    @libQt5Multimedia.so@

    and

    @libQt5Multimedia.la@

    and some others.
    but i have not

    @libQt5Multimedia@

    specifically. and of course its 5.3.2 for me.(just saying)



  • Have you tried to open and build multimedia examples from Qt?

    For example
    @
    $ cd ~/Qt5.3.2/Examples/Qt-5.3/multimediawidgets
    $ mkdir build-videographicsitem
    $ ~/Qt5.3.2/5.3/gcc_64/bin/qmake ../videographicsitem/
    $ make
    ..... compilation without any errors and warnings
    $ ./videographicsitem
    Warning: "No decoder available for type 'video/x-ms-asf'."
    Error: "Your GStreamer installation is missing a plug-in."
    ..... Looks like I have not install all necessary gstreamer0.10 plugins
    @

    Do you get the same error as in your project?



  • after make i get this exact error:

    @g++ -Wl,-O1 -Wl,-rpath,/home/elshen/Qt5.3.2/5.3/gcc_64 -Wl,-rpath,/home/elshen/Qt5.3.2/5.3/gcc_64/lib -Wl,-rpath-link,/home/elshen/Qt5.3.2/5.3/gcc_64/lib -o videographicsitem main.o videoplayer.o moc_videoplayer.o -L/home/elshen/Qt5.3.2/5.3/gcc_64/lib -lQt5MultimediaWidgets -lQt5Multimedia -lQt5Widgets -lQt5Network -lQt5Gui -lQt5Core -lGL -lpthread
    /usr/bin/ld: cannot open output file videographicsitem: Is a directory
    collect2: error: ld returned 1 exit status
    make: *** [videographicsitem] Error 1@

    whats now? whats the problem?



  • Oops. I forgot to put "cd build-videographicsitem" in the steps above.

    Here is a correct set of steps
    @
    $ cd ~/Qt5.3.2/Examples/Qt-5.3/multimediawidgets
    $ mkdir build-videographicsitem
    $ cd build-videographicsitem
    $ ~/Qt5.3.2/5.3/gcc_64/bin/qmake ../videographicsitem/
    $ make
    ..... compilation without any errors and warnings
    $ ./videographicsitem
    @



  • ok, now it works :D
    the application opens and
    this is the output after opening a video:

    @(gst-plugin-scanner:32745): GStreamer-WARNING **: Failed to load plugin '/usr/lib/gstreamer-0.10/libgstsimsyn.so': /usr/lib/gstreamer-0.10/libgstsimsyn.so: undefined symbol: gst_controller_sync_values

    (gst-plugin-scanner:32745): GStreamer-WARNING **: Failed to load plugin '/usr/lib/gstreamer-0.10/libgstaudiodelay.so': /usr/lib/gstreamer-0.10/libgstaudiodelay.so: undefined symbol: gst_base_transform_set_gap_aware

    (gst-plugin-scanner:32745): GStreamer-WARNING **: Failed to load plugin '/usr/lib/gstreamer-0.10/libgstbml.so': /usr/lib/gstreamer-0.10/libgstbml.so: undefined symbol: gst_base_src_set_format

    (videographicsitem:32737): GStreamer-CRITICAL **: gst_pad_link_full: assertion 'GST_IS_PAD (sinkpad)' failed
    Error: "GStreamer encountered a general stream error."@



  • Ok, i removed Qt cache from /home today and now it works correctly.
    thanks for your helps.

    now the gstreamer problem,
    i opened the file that you said(videographicitem)
    like i said before, it can play some of videos, but cant play some of them.
    the error is:

    @(videographicsitem:24715): GStreamer-CRITICAL **: gst_pad_link_full: assertion 'GST_IS_PAD (sinkpad)' failed
    Error: "GStreamer encountered a general stream error."@

    whats the problem? what i have to do?

    i actually find out why the cache was broken.
    i open qtcreator from /usr/bin/qtcreator.
    in that address there is no example or libraries or anything for qt
    and because of that, nothing works.
    but after cleaning cache and run qt from ~/Qt5.3.2/Tools/QtCreator/bin/qtcreator
    all the examples and libraries work correctly. so why is that?!



  • i should add this to the preview post that:
    i used QGraphicVideoItem and with that i had problem.
    but then, i used VideoWidget and its play all the videos (though the error shows, even now!)
    but i want to use QGraphicTextItem and cant use it with VideoWidget.
    so, what can i do?


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