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Play audio source from camera? (Capture Card)

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  • SGaistS Offline
    SGaistS Offline
    SGaist
    Lifetime Qt Champion
    wrote on last edited by
    #7

    Are you on Linux ?

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

    B 1 Reply Last reply
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    • SGaistS SGaist

      Are you on Linux ?

      B Offline
      B Offline
      BrianL
      wrote on last edited by
      #8

      @SGaist on Windows

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      • SGaistS Offline
        SGaistS Offline
        SGaist
        Lifetime Qt Champion
        wrote on last edited by
        #9

        QCamera does not do audio therefore on Linux you could have "cheated" with GStreamer but I do not think you can do something similar on Windows.

        Maybe switch the capture part over to VLC ?

        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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        • SGaistS SGaist

          QCamera does not do audio therefore on Linux you could have "cheated" with GStreamer but I do not think you can do something similar on Windows.

          Maybe switch the capture part over to VLC ?

          B Offline
          B Offline
          BrianL
          wrote on last edited by
          #10

          @SGaist thanks for the suggestion, upon looking into the libraries, it looks like I can pass QUrl into it, but wouldn't that imply I need to stream the footage on the network first before I can pass to VLC?

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          • SGaistS Offline
            SGaistS Offline
            SGaist
            Lifetime Qt Champion
            wrote on last edited by
            #11

            Sorry, I was suggesting to use libVLC and VLC-Qt in your application.

            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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            • SGaistS SGaist

              Sorry, I was suggesting to use libVLC and VLC-Qt in your application.

              B Offline
              B Offline
              BrianL
              wrote on last edited by BrianL
              #12

              @SGaist Yep, soo I was able to get VLC-Qt working somewhat in my application, however there are a few warnings a errors I am getting

              1. When I initialize the vlc instance:
              m_instance = new VlcInstance(VlcCommon::args(), this);
              

              it gives me this warning:

              QObject: Cannot create children for a parent that is in a different thread. (Parent is MainWindow(0x73fe00), parent's thread is QThread(0x1e41c7b8), current thread is QThread(0x1fbd3b08)
              

              I suppose this was not the biggest problem since I can just not parent with my mainwindow and delete it manually.

              1. I was able to get the video footage, however the audio does not work, I start the media with the following code:
              QString url = "dshow://";
                  m_media = new VlcMedia(url, m_instance);
                  QStringList list;
                  list << ":dshow-vdev=LGPLite Stream Engine";
                  list << ":dshow-adev=LGPLite Stream Engine";
                  list << ":dshow-aspect-ratio=16:9";
                  m_media->setOptions(list);
                  m_player->open(m_media);
              

              I grabbed the option strings directly from when I was testing getting footage in VLC Player (32-bit), and it was working perfectly fine there, so I was not quite sure why it is not working here, perhaps missing settings/options? The error I am getting is this:

              dshow demux error: can't use device: LGPLite Stream Engine, unsupported device type
              libvlc: can't use device: LGPLite Stream Engine, unsupported device type
              core demux error: Capture failed
              libvlc: Capture failed
              core demux error: The device you selected cannot be used, because its type is not supported.
              libvlc: The device you selected cannot be used, because its type is not supported.
              dshow demux error: can't open audio device
              libvlc: can't open audio device
              

              EDIT: I tried setting up OBS Virtual Camera with options:

              list << ":dshow-vdev=OBS-Camera";
              list << ":dshow-adev=OBS-Audio";
              

              I was able to get the audio too, but obviously that way is not very intuitive and it relies on yet another application to get this to work...

              1. When I tried to use VlcWidgetVideo (this should allow me to display video on my application, without this I can still get video but it creates a separate window for me), it gave me this error:
              QWidget: Must construct a QApplication before a QWidget
              

              I did this is two ways, one is to promote a QWidget to the VlcWidgetVideo with path VLCQtWidgets/WidgetVideo.h (I have already included the path in .pro). The other way is I initialize it dynamically in code:

              m_video = new VlcWidgetVideo(this);
              ui->verticalLayout->addWidget(m_video);
              

              However both is giving me the same error message and crashed the application :(

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              • SGaistS Offline
                SGaistS Offline
                SGaist
                Lifetime Qt Champion
                wrote on last edited by
                #13

                Are you able to have both in VLC itself ?

                The error makes it look like you are not doing things in the right order.

                Did you forgot QApplication ?

                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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                • SGaistS SGaist

                  Are you able to have both in VLC itself ?

                  The error makes it look like you are not doing things in the right order.

                  Did you forgot QApplication ?

                  B Offline
                  B Offline
                  BrianL
                  wrote on last edited by
                  #14

                  @SGaist
                  When I test it in VLC Player I was able to get video and audio just fine.

                  The VlcWidgetVideo class is initialized in mainwindow.cpp, not in main.cpp, the main.cpp is just the default one with one line added for Qt-VLC:

                  int main(int argc, char *argv[])
                  {
                  
                      QApplication a(argc, argv);
                      VlcCommon::setPluginPath(a.applicationDirPath() + "/plugins");
                  
                      MainWindow w;
                      w.show();
                      return a.exec();
                  }
                  

                  I do have the plugins at the exe directory and it wasn't the cause of the problems

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                  • SGaistS Offline
                    SGaistS Offline
                    SGaist
                    Lifetime Qt Champion
                    wrote on last edited by
                    #15

                    Do you have the same issue if you use the VLC-Qt C++ example ?

                    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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                    • SGaistS SGaist

                      Do you have the same issue if you use the VLC-Qt C++ example ?

                      B Offline
                      B Offline
                      BrianL
                      wrote on last edited by BrianL
                      #16

                      @SGaist Yep, it has the exact same problem

                      QWidget: Must construct a QApplication before a QWidget
                      

                      Just a little more info my build is Qt 5.13.1 MinGW 32-bit, and I have the MinGW version of VLC-Qt downloaded, it compiles without any error

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                      • B Offline
                        B Offline
                        BrianL
                        wrote on last edited by BrianL
                        #17

                        So I tried this demo code instead of VLC-Qt:
                        https://wiki.videolan.org/LibVLC_SampleCode_Qt/

                        And first it couldn't get the audio yet again, but then I tried to replace the plugin and .dll from the latest VLC player as I was using the ones from VLC-Qt, turns out those are very outdated and now the audio is working! And this is also able to display within Qt widget by directly using libvlc code instead of custom widget from VLC-Qt.

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                        • SGaistS Offline
                          SGaistS Offline
                          SGaist
                          Lifetime Qt Champion
                          wrote on last edited by
                          #18

                          Nice !

                          I haven't had the time to check for the VLC-Qt error but it is quite strange as it usually has to do with some static widget creation when the QApplication object is not missing.

                          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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