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Forum Update on Monday, May 27th 2025

VLC-Qt build error

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  • N Offline
    N Offline
    NewUser2023
    wrote on 2 Nov 2023, 06:41 last edited by NewUser2023 11 Feb 2023, 06:43
    #1

    Hi, I am trying to test out on VLC with QT to build a video player.

    Some info on what software I am using:
    QT 6.6
    compiling with QT qmake, msvc2019_64
    Had Installed VLC

    I am following the guideline in this website
    http://derekmolloy.ie/custom-video-streaming-player-using-libvlc-and-qt/

    I had downloaded this [simple-player] example from
    https://github.com/vlc-qt/examples

    But when i open the example above in QT and try to build it

    I encountered this 2 errors, can anyone advise how to resolve?
    its highlighting the VlcCommon and VlcInstance classes

    mainwindow.obj:-1: error: LNK2019: unresolved external symbol "__declspec(dllimport) class QList<class QString> __cdecl VlcCommon::args(void)" (_imp?args@VlcCommon@@YA?AV?$QList@VQString@@@@XZ) referenced in function "public: __cdecl MainWindow::MainWindow(class QWidget *)" (??0MainWindow@@QEAA@PEAVQWidget@@@Z)

    mainwindow.obj:-1: error: LNK2019: unresolved external symbol "__declspec(dllimport) public: __cdecl VlcInstance::VlcInstance(class QList<class QString> const &,class QObject *)" (_imp??0VlcInstance@@QEAA@AEBV?$QList@VQString@@@@PEAVQObject@@@Z) referenced in function "public: __cdecl MainWindow::MainWindow(class QWidget *)" (??0MainWindow@@QEAA@PEAVQWidget@@@Z)

    7e157fa1-a1d0-401b-a40e-dced3a2e97b9-image.png

    J 1 Reply Last reply 2 Nov 2023, 09:24
    0
    • N NewUser2023
      2 Nov 2023, 06:41

      Hi, I am trying to test out on VLC with QT to build a video player.

      Some info on what software I am using:
      QT 6.6
      compiling with QT qmake, msvc2019_64
      Had Installed VLC

      I am following the guideline in this website
      http://derekmolloy.ie/custom-video-streaming-player-using-libvlc-and-qt/

      I had downloaded this [simple-player] example from
      https://github.com/vlc-qt/examples

      But when i open the example above in QT and try to build it

      I encountered this 2 errors, can anyone advise how to resolve?
      its highlighting the VlcCommon and VlcInstance classes

      mainwindow.obj:-1: error: LNK2019: unresolved external symbol "__declspec(dllimport) class QList<class QString> __cdecl VlcCommon::args(void)" (_imp?args@VlcCommon@@YA?AV?$QList@VQString@@@@XZ) referenced in function "public: __cdecl MainWindow::MainWindow(class QWidget *)" (??0MainWindow@@QEAA@PEAVQWidget@@@Z)

      mainwindow.obj:-1: error: LNK2019: unresolved external symbol "__declspec(dllimport) public: __cdecl VlcInstance::VlcInstance(class QList<class QString> const &,class QObject *)" (_imp??0VlcInstance@@QEAA@AEBV?$QList@VQString@@@@PEAVQObject@@@Z) referenced in function "public: __cdecl MainWindow::MainWindow(class QWidget *)" (??0MainWindow@@QEAA@PEAVQWidget@@@Z)

      7e157fa1-a1d0-401b-a40e-dced3a2e97b9-image.png

      J Online
      J Online
      jsulm
      Lifetime Qt Champion
      wrote on 2 Nov 2023, 09:24 last edited by
      #2

      @NewUser2023 Looks like VLC-Qt lib is not linked. Check the build output to see whether linker complains about not found libraries. Did you build VLC-Qt lib?

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

      N 1 Reply Last reply 2 Nov 2023, 10:46
      0
      • J jsulm
        2 Nov 2023, 09:24

        @NewUser2023 Looks like VLC-Qt lib is not linked. Check the build output to see whether linker complains about not found libraries. Did you build VLC-Qt lib?

        N Offline
        N Offline
        NewUser2023
        wrote on 2 Nov 2023, 10:46 last edited by
        #3

        @jsulm

        Thanks for your response

        I am new to C++, may I know what do you mean by build the VLC-QT?

        I didn't build or convert the VLC-QT lib files i downloaded from
        https://vlc-qt.tano.si/ -> https://github.com/vlc-qt/vlc-qt/releases/download/1.1.0/VLC-Qt_1.1.0_win64_msvc2015.7z

        I saw there is VLCQtCore.dll and VLCQtCore.lib inside the VLC-QT lib folders, can I assume don't need to build?

        Thanks

        J 1 Reply Last reply 2 Nov 2023, 11:46
        1
        • N NewUser2023
          2 Nov 2023, 10:46

          @jsulm

          Thanks for your response

          I am new to C++, may I know what do you mean by build the VLC-QT?

          I didn't build or convert the VLC-QT lib files i downloaded from
          https://vlc-qt.tano.si/ -> https://github.com/vlc-qt/vlc-qt/releases/download/1.1.0/VLC-Qt_1.1.0_win64_msvc2015.7z

          I saw there is VLCQtCore.dll and VLCQtCore.lib inside the VLC-QT lib folders, can I assume don't need to build?

          Thanks

          J Online
          J Online
          jsulm
          Lifetime Qt Champion
          wrote on 2 Nov 2023, 11:46 last edited by
          #4

          @NewUser2023 OK, you're using prebuild VLC-Qt, that's fine.
          How do you build the example? Using CMake or QMake? How do you call CMake or QMake? How does their output look like?

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

          N 2 Replies Last reply 2 Nov 2023, 23:47
          0
          • J jsulm
            2 Nov 2023, 11:46

            @NewUser2023 OK, you're using prebuild VLC-Qt, that's fine.
            How do you build the example? Using CMake or QMake? How do you call CMake or QMake? How does their output look like?

            N Offline
            N Offline
            NewUser2023
            wrote on 2 Nov 2023, 23:47 last edited by
            #5

            @jsulm said in VLC-Qt build error:
            Hi
            I am using qmake, build using QT-Creator, i was trying to build a "release" version of it
            21f97c50-6776-4d30-ab10-ed23f4518330-image.png

            here is how the release folder look like, do i need to paste the missing lib /dll here?
            6b80ab43-3aad-4efe-9889-dcf395a1cb13-image.png

            When i create my project, i selected this MSVC2019 64 bit kit
            b13c617e-2936-4931-93b5-0886701b0025-image.png

            here is my workspace structure, the library I downloaded, i just extract and place them here
            0965e3c1-69a6-4581-9faf-eb7420a6d3e7-image.png

            inside the lib folder, there is the lib files , VLCQtCore.lib etc...
            inside the include folder, there is the header files , VideoDelegate.h etc
            inside the bin folder, there is the dll files, VLCQtCore.dll etc

            is there any step which i missed to "import" the library?

            1 Reply Last reply
            0
            • J jsulm
              2 Nov 2023, 11:46

              @NewUser2023 OK, you're using prebuild VLC-Qt, that's fine.
              How do you build the example? Using CMake or QMake? How do you call CMake or QMake? How does their output look like?

              N Offline
              N Offline
              NewUser2023
              wrote on 2 Nov 2023, 23:56 last edited by
              #6

              @jsulm

              Hi

              just to add on

              I also downloaded the LibVLC from here [VLC source code tar.xz ]
              https://www.videolan.org/vlc/download-sources.html

              And I copied out these folder to be place in my QT installation dir
              inside the include, plugin and lib folder
              6c6a5219-1145-49e3-bef9-53725925b63e-image.png

              QT installation dir
              fcc22230-ed62-4cc6-a999-4cd9202fb9c8-image.png

              J 1 Reply Last reply 3 Nov 2023, 07:24
              0
              • N NewUser2023
                2 Nov 2023, 23:56

                @jsulm

                Hi

                just to add on

                I also downloaded the LibVLC from here [VLC source code tar.xz ]
                https://www.videolan.org/vlc/download-sources.html

                And I copied out these folder to be place in my QT installation dir
                inside the include, plugin and lib folder
                6c6a5219-1145-49e3-bef9-53725925b63e-image.png

                QT installation dir
                fcc22230-ed62-4cc6-a999-4cd9202fb9c8-image.png

                J Online
                J Online
                jsulm
                Lifetime Qt Champion
                wrote on 3 Nov 2023, 07:24 last edited by
                #7

                @NewUser2023 said in VLC-Qt build error:

                And I copied out these folder to be place in my QT installation dir

                This is not a good idea.
                You just need to define in your pro file where to find VLC-Qt libs and headers.
                See https://doc.qt.io/qt-6/qmake-variable-reference.html#libs and https://doc.qt.io/qt-6/qmake-variable-reference.html#includepath

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

                N 1 Reply Last reply 3 Nov 2023, 11:48
                0
                • J jsulm
                  3 Nov 2023, 07:24

                  @NewUser2023 said in VLC-Qt build error:

                  And I copied out these folder to be place in my QT installation dir

                  This is not a good idea.
                  You just need to define in your pro file where to find VLC-Qt libs and headers.
                  See https://doc.qt.io/qt-6/qmake-variable-reference.html#libs and https://doc.qt.io/qt-6/qmake-variable-reference.html#includepath

                  N Offline
                  N Offline
                  NewUser2023
                  wrote on 3 Nov 2023, 11:48 last edited by
                  #8

                  @jsulm

                  Hi,

                  yes, i did that as well, just as shown in the example project.

                  05b77c7f-631f-4d60-8ac7-901d0d120f5e-image.png

                  J 1 Reply Last reply 3 Nov 2023, 12:08
                  0
                  • N NewUser2023
                    3 Nov 2023, 11:48

                    @jsulm

                    Hi,

                    yes, i did that as well, just as shown in the example project.

                    05b77c7f-631f-4d60-8ac7-901d0d120f5e-image.png

                    J Online
                    J Online
                    jsulm
                    Lifetime Qt Champion
                    wrote on 3 Nov 2023, 12:08 last edited by
                    #9

                    @NewUser2023 Please post text not pictures.
                    In your LIBS you use PWD - make sure the path is really valid and check the linker call to see what paths are passed to the linker.

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

                    1 Reply Last reply
                    0

                    1/9

                    2 Nov 2023, 06:41

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