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QT OpenCV Play Pause and Stop Video

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  • S Offline
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    Stevendragoes
    wrote on last edited by
    #5

    Alright @jsulm, I will try it out and Will update accordingly. Thank you for your assistance

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    • S Offline
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      Stevendragoes
      wrote on last edited by
      #6

      @jsulm and I am guessing getNewFrame is the function that I have to implement so that I get the new frame?

      jsulmJ 1 Reply Last reply
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      • S Stevendragoes

        @jsulm and I am guessing getNewFrame is the function that I have to implement so that I get the new frame?

        jsulmJ Offline
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        jsulm
        Lifetime Qt Champion
        wrote on last edited by
        #7

        @Stevendragoes said in QT OpenCV Play Pause and Stop Video:

        and I am guessing getNewFrame is the function that I have to implement so that I get the new frame?

        Yes

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

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          Stevendragoes
          wrote on last edited by
          #8

          Hello @jsulm
          When I implement getNewFrame, I can't even get the path to print on the text edit. Any Reason why? I know it is triggering every 1 second, and I am trying to append every one second as well?

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            Stevendragoes
            wrote on last edited by
            #9

            @jsulm
            db330cbf-9dbb-474f-982d-59344137290a-image.png

            qpath is loaded into by FileDialog

            jsulmJ 1 Reply Last reply
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            • S Stevendragoes

              @jsulm
              db330cbf-9dbb-474f-982d-59344137290a-image.png

              qpath is loaded into by FileDialog

              jsulmJ Offline
              jsulmJ Offline
              jsulm
              Lifetime Qt Champion
              wrote on last edited by
              #10

              @Stevendragoes said in QT OpenCV Play Pause and Stop Video:

              qpath

              Do you assign the path selected in the file dialog to it? Please show your code, else I can only guess.

              "I know it is triggering every 1 second, and I am trying to append every one second as well?" - if you did not change the timeout period then yes it is triggered once each second.

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

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                Stevendragoes
                wrote on last edited by
                #11

                @jsulm said in QT OpenCV Play Pause and Stop Video:

                Do you assign the path selected in the file dialog to it?

                Hello @jsulm
                6c06a870-02f9-4a11-b478-622f8ca6e627-image.png

                I assighed the qpath after I pressed Load PushButton in the UI

                jsulmJ 1 Reply Last reply
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                • S Stevendragoes

                  @jsulm said in QT OpenCV Play Pause and Stop Video:

                  Do you assign the path selected in the file dialog to it?

                  Hello @jsulm
                  6c06a870-02f9-4a11-b478-622f8ca6e627-image.png

                  I assighed the qpath after I pressed Load PushButton in the UI

                  jsulmJ Offline
                  jsulmJ Offline
                  jsulm
                  Lifetime Qt Champion
                  wrote on last edited by
                  #12

                  @Stevendragoes Are you sure your timer is actually running? And are you sure you connected the slot for the timer properly?

                  Please post your code as text, not as screen shot, then it is easier to others to change it if there is something wrong.

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

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                    Stevendragoes
                    wrote on last edited by
                    #13
                    cShowVideo::cShowVideo(Ui::MainWindow& ui, std::string& path, QString& qpath, MainWindow &parent) : MainWindow()
                    {
                        timer = new QTimer(this);
                        connect(timer,SIGNAL(timeout()),this,SLOT(getNextFrame()));
                        //ui.textEdit->setText(qpath);
                        timer->start(1000);
                        DisplayVideo(ui,path,parent);
                    

                    this is my timer code. It starts properly.
                    when i used qDebug, it shows the text in 1 second which means that the Timer function is working?
                    However, when I change it to the text edit, as shown below, the text is not appearing as intended
                    The code printing is as follows:

                    void MainWindow::getNextFrame()
                    {
                        qDebug("Get Next Frame is working");
                        ui->textEdit->append("GetNextFrame");
                    }
                    
                    

                    To show its working, the "Get Next Frame is working" is printing every second
                    cc2daa6d-75d7-42d1-9596-5e7fe43a2ce7-image.png

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                    • S Offline
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                      Stevendragoes
                      wrote on last edited by
                      #14

                      @jsulm Sorry forgot to tag you

                      jsulmJ 1 Reply Last reply
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                      • S Stevendragoes

                        @jsulm Sorry forgot to tag you

                        jsulmJ Offline
                        jsulmJ Offline
                        jsulm
                        Lifetime Qt Champion
                        wrote on last edited by
                        #15

                        @Stevendragoes Do you still have the loop in DisplayVideo?

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

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                          Stevendragoes
                          wrote on last edited by
                          #16

                          @jsulm Yes I do have the loop, Should I take it out first?

                          jsulmJ 1 Reply Last reply
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                          • S Stevendragoes

                            @jsulm Yes I do have the loop, Should I take it out first?

                            jsulmJ Offline
                            jsulmJ Offline
                            jsulm
                            Lifetime Qt Champion
                            wrote on last edited by
                            #17

                            @Stevendragoes said in QT OpenCV Play Pause and Stop Video:

                            Should I take it out first?

                            Of course. As I said before this loop is blocking the event loop, so UI does not work properly.

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

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                              Stevendragoes
                              wrote on last edited by
                              #18

                              @jsulm When I commented out the loop, the timer doesn't run anymore.

                              jsulmJ 1 Reply Last reply
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                              • S Stevendragoes

                                @jsulm When I commented out the loop, the timer doesn't run anymore.

                                jsulmJ Offline
                                jsulmJ Offline
                                jsulm
                                Lifetime Qt Champion
                                wrote on last edited by
                                #19

                                @Stevendragoes Please comment out DisplayVideo call in cShowVideo

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

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                                  Stevendragoes
                                  wrote on last edited by
                                  #20

                                  I have commented it out also.
                                  However, what I want is that when I load the video, the timer to start. So, I initialised the timer in the cShowvideo which is a class inherited from the MainWindow().
                                  Is that an incorrect way of doing so?

                                  jsulmJ 1 Reply Last reply
                                  0
                                  • S Stevendragoes

                                    I have commented it out also.
                                    However, what I want is that when I load the video, the timer to start. So, I initialised the timer in the cShowvideo which is a class inherited from the MainWindow().
                                    Is that an incorrect way of doing so?

                                    jsulmJ Offline
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                                    jsulm
                                    Lifetime Qt Champion
                                    wrote on last edited by
                                    #21

                                    @Stevendragoes As I said already: in the slot connected to the timer you get next frame and show it. You need to implement this to make it work.

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

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                                      Stevendragoes
                                      wrote on last edited by
                                      #22

                                      Yeap. I think I figured it out.
                                      I shifted the initialisation of the timer in the MainWindow.

                                      MainWindow::MainWindow(QWidget *parent): QMainWindow(parent), ui(new Ui::MainWindow)
                                      {
                                          timer = new QTimer(this);
                                          connect(timer,SIGNAL(timeout()),this,SLOT(getNextFrame()));
                                          ui->setupUi(this);
                                      }
                                      
                                      

                                      and I used the cShowVideo Class to start the timer when I load the video from the FileDialog

                                      cShowVideo::cShowVideo(Ui::MainWindow& ui, std::string& path, QString& qpath, MainWindow &parent) : MainWindow()
                                      {
                                          parent.timer->start(1000);
                                          ui.textEdit->append(qpath);
                                      }
                                      

                                      and it works, it is appending every second.

                                      jsulmJ 1 Reply Last reply
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                                        Stevendragoes
                                        wrote on last edited by
                                        #23

                                        @jsulm
                                        From what I saw in the QTimer Class, there is no such thing as pause the timer?

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                                        • S Stevendragoes

                                          Yeap. I think I figured it out.
                                          I shifted the initialisation of the timer in the MainWindow.

                                          MainWindow::MainWindow(QWidget *parent): QMainWindow(parent), ui(new Ui::MainWindow)
                                          {
                                              timer = new QTimer(this);
                                              connect(timer,SIGNAL(timeout()),this,SLOT(getNextFrame()));
                                              ui->setupUi(this);
                                          }
                                          
                                          

                                          and I used the cShowVideo Class to start the timer when I load the video from the FileDialog

                                          cShowVideo::cShowVideo(Ui::MainWindow& ui, std::string& path, QString& qpath, MainWindow &parent) : MainWindow()
                                          {
                                              parent.timer->start(1000);
                                              ui.textEdit->append(qpath);
                                          }
                                          

                                          and it works, it is appending every second.

                                          jsulmJ Offline
                                          jsulmJ Offline
                                          jsulm
                                          Lifetime Qt Champion
                                          wrote on last edited by
                                          #24

                                          @Stevendragoes This is not good design - child should not access parent members directly. And this timer does not belong to MainWindow but to cShowVideo. Move timer again to cShowVideo.
                                          I just noticed that cShowVideo is a local variable in on_actionLoad_Video_triggered(). That means it is destroyed as soon as on_actionLoad_Video_triggered() finishes - that's why your timer is not working. Make sure cShowVideo instance lives as long as it is playing video.
                                          Also another note regarding design: your cShowVideo should not know anything about the MainWindow UI. This issue is called tight coupling and makes the maintenance of your software harder. In cShowVideo you should only get next frame and send it to MainWindow via a slot, MainWindow knows better how to use its UI to show the frames.

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

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