Media player not working for multiple videos

[Kinesis]

@jsulm
I got a lambda issue for "m_playButton" . The message is " m_play Button in capture list does not name a variable.

[jsulm]

@Kinesis Please show your code...
You need to put the code I shown AFTER you created m_playButton.

[aha_1980]

@Kinesis I will tell you my insights from reading this thread: you should really take a C++ book and start with simple examples.

you are lacking simple programming knowledge, sorry. most of your problems are not related to Qt.

So please, start learning C++. it will help you a lot.

[Kinesis]

@aha_1980
Thanks for your suggestion . I am learning c++ now . I also like to try writing UI that's why I am approaching QT .

[Kinesis]

@jsulm
Here is the code

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    
    ui->listWidget->setFlow(QListView::LeftToRight);
    ui->listWidget->setMinimumSize(1200,350);
    ui->listWidget->setGridSize(QSize(360, 360));
    ui->listWidget->setResizeMode(QListView::Adjust);
    ui->listWidget->setViewMode(QListView::ListMode);
    ui->listWidget->setWrapping(true);
    
    QDir directory = QFileDialog::getExistingDirectory(this, tr("Open Directory"),"/home",
                                                       
                                                       QFileDialog::ShowDirsOnly| QFileDialog::DontResolveSymlinks);
    
    directory.setNameFilters({"*.mp4" , "*.avi" , "*.flv" , "*.mwv"});
    
    for(const QFileInfo & finfo: directory.entryInfoList()){
        QMediaPlayer *mediaPlayer = new QMediaPlayer();
        mediaPlayer->setMedia(QUrl::fromLocalFile(finfo.absoluteFilePath()));
        // mediaPlayer->setMedia(playlist);
        videoItem = new QGraphicsVideoItem;
        videoItem->setSize(QSize(320,240));
        QGraphicsScene *scene = new QGraphicsScene(this);
        QGraphicsView *graphicsView = new QGraphicsView(scene);
        
        
        
        
        mediaPlayer->setVideoOutput(videoItem);
        player.append(mediaPlayer);
        scene->addItem(videoItem);
        
        connect(mediaPlayer, &QMediaPlayer::stateChanged, this, &MainWindow::mediaStateChanged);
        
        connect(mediaPlayer, &QMediaPlayer::positionChanged, this, &MainWindow::positionChanged);
        connect(mediaPlayer, &QMediaPlayer::durationChanged, this, &MainWindow::durationChanged);
        
        m_playButton = new QPushButton;
        m_playButton->setIcon(style()->standardIcon(QStyle::SP_MediaPlay));
        
        connect(m_playButton, &QAbstractButton::clicked, [mediaPlayer]() {
            switch (mediaPlayer->state()) {
            case QMediaPlayer::PlayingState:
                mediaPlayer->pause();
                break;
            default:
                mediaPlayer->play();
                break;
            }
        });
        
        connect(mediaPlayer, &QMediaPlayer::stateChanged, [m_playButton, this](QMediaPlayer::State state) {
            switch(state) {
            case QMediaPlayer::PlayingState:
                m_playButton->setIcon(style()->standardIcon(QStyle::SP_MediaPause));
                break;
            default:
                m_playButton->setIcon(style()->standardIcon(QStyle::SP_MediaPlay));
                break;
            }
        });
        
        
        //connect(m_playButton, &QAbstractButton::clicked, this, &MainWindow::play);
        //connect(m_positionSlider, &QAbstractSlider::sliderMoved,this, &MainWindow::setPosition);
        
        
        
        m_positionSlider = new QSlider(Qt::Horizontal);
        m_positionSlider->setRange(0, 0);
        
        
        auto    item = new QListWidgetItem("", ui->listWidget);
        auto    widget = new QWidget;
        auto    label = new QLabel(finfo.fileName());
        auto    vb = new QVBoxLayout;
        
        QBoxLayout *controlLayout = new QHBoxLayout;
        controlLayout->setMargin(0);
        controlLayout->addWidget(m_playButton);
        controlLayout->addWidget(m_positionSlider);
        
        vb->addWidget(label,1);
        vb->addWidget(graphicsView,9);
        vb->addLayout(controlLayout);
        widget->setLayout(vb);
        widget->setMinimumSize(340, 340);
        ui->listWidget->setItemWidget(item,widget);
        
        
    }
        
}
MainWindow::~MainWindow()
{
    delete ui;
}
QSize MainWindow::sizeHint() const
{
    return (videoItem->size() * qreal(3) / qreal(2)).toSize();
}

void MainWindow::positionChanged(qint64 position)
{
    m_positionSlider->setValue(position);
}

void MainWindow::durationChanged(qint64 duration)
{
    m_positionSlider->setRange(0, duration);
}

void MainWindow::setPosition(int position)
{
    QMediaPlayer *mediaPlayer = player[1];
    mediaPlayer->setPosition(position);
}

[jsulm]

@Kinesis And exactly this code does not build?

[Devopia53]

@Kinesis

Declare QPushButton as a local variable like a mediaPlayer. A lambda function can not capture member variables of this.

[aha_1980]

@Devopia53 No, it can:

auto l = [this]() {
  // use members of this here
}

[Kinesis]

@jsulm - Yes it does not work
@Devopia53 - When I declare local variable , it works.
@aha_1980 - I will also try like U said .
Sorry for replying in the same reply . Because I am a new user . I can only post per every 600s

[Kinesis]

I still have a question . I replaced the slider slots into loop but I can't control the sliders and sliders are not moving when the videos are running .
Here is the slider code

QSlider *m_positionSlider = new QSlider(Qt::Horizontal);
        m_positionSlider->setRange(0, 0);

       
        connect(mediaPlayer, &QMediaPlayer::positionChanged ,[m_positionSlider, this](qint64 position){

            m_positionSlider->setValue(position);
        });

        connect(mediaPlayer, &QMediaPlayer::durationChanged ,[m_positionSlider, this](qint64 duration){

            m_positionSlider->setRange(0,duration);
        });


        connect(mediaPlayer , &QMediaPlayer::setPosition, [mediaPlayer ,this] (int position){

            mediaPlayer->setPosition(position);
        });

[jsulm]

@Kinesis What is this:

connect(mediaPlayer , &QMediaPlayer::setPosition, [mediaPlayer ,this] (int position){

            mediaPlayer->setPosition(position);
        });

?
QMediaPlayer::setPosition() is a slot not a signal.
I think you need to change the range

m_positionSlider->setRange(0, 0);

You can use http://doc.qt.io/qt-5/qmediaplayer.html#duration-prop to set the range.

[Devopia53]

@aha_1980

I know that well(as [&] or [=]). But what I have described is that you have captured the member variables of the this object directly. Take a look at his source code. here: connect(mediaPlayer, &QMediaPlayer::stateChanged, [m_playButton, this](QMediaPlayer::State state)
A m_playButton is a member of the this.

[Kinesis]

@jsulm
Thanks for your suggestion . Now the slider is running along with video.But to use it like skip slider how should I correct this "QMediaPlayer::setPosition() " which is a slot but not a signal ?By the way , sorry for late response .

[jsulm]

@Kinesis You don't need

connect(mediaPlayer , &QMediaPlayer::setPosition, [mediaPlayer ,this] (int position){

            mediaPlayer->setPosition(position);
        });

You're already using QMediaPlayer::positionChanged...

[Kinesis]

@jsulm
I got this. It's done now. My code is working fully 100% now . Thanks a lot for helping me . I fell bad that I wasted your time . By the way should I upload my
code ? It might help someone . Thanks.

[jsulm]

@Kinesis No need to feel bad - I'm helping here voluntary :-)
I don't think you need to upload your code. If somebody has questions he/she can ask.

[WoodyLanes]

This post is deleted!