Media player not working for multiple videos

[jsulm]

@Kinesis What is the problem with connect()? You have the pointer to QMediaPlayer inside the loop where you call connect():

for(const QFileInfo & finfo: directory.entryInfoList()){
    QMediaPlayer *mediaPlayer = new QMediaPlayer(); // You need to create one for each video as you want to show all at the same time, right?
    mediaPlayer->setMedia(QUrl::fromLocalFile(finfo.absoluteFilePath()));
    connect(mediaPlayer, &QMediaPlayer::stateChanged, this, &MainWindow::mediaStateChanged);
...
    mediaPlayer->setVideoOutput(m_videoItem);
    m_mediaPlayer.append(mediaPlayer);

[Kinesis]

@jsulm
It keeps showing "error: use of undeclared identifier 'mediaPlayer' " like in this slot

void MainWindow::play()
{
    switch (mediaPlayer->state()) {
    case QMediaPlayer::PlayingState:
        mediaPlayer->pause();
        break;
    default:
        mediaPlayer->play();
        break;
    }
}

[jsulm]

@Kinesis And how is this related to connect() call?
You need to understand: you have MANY media players, not just one. You put all of them in a list. That means if user presses play you need to get the one media player user wants to play. And then use this player.
Something like:

void MainWindow::play()
{
    QMediaPlayer *mediaPlayer = player[currentIndex];
    switch (mediaPlayer->state()) {
    case QMediaPlayer::PlayingState:
        mediaPlayer->pause();
        break;
    default:
        mediaPlayer->play();
        break;
    }
}

I don't know how to determine the value of currentIndex, as I don't know much about your app.

[Kinesis]

@jsulm
Its seem like it will work this time. How can I determine the value of currentIndex?

[jsulm]

@Kinesis "How can I determine the value of currentIndex?" - as I said - I don't know.
How does the user select the video to play?

[Kinesis]

@jsulm
I found that the buttons are linking each other . If I press the play button of 1st video It also play second video . How can I fix that .

[jsulm]

@Kinesis You could use lambda (C++11: https://en.cppreference.com/w/cpp/language/lambda):

connect(m_playButton, &QAbstractButton::clicked, [mediaPlayer]() {
switch (mediaPlayer->state()) {
case QMediaPlayer::PlayingState:
    mediaPlayer->pause();
    break;
default:
    mediaPlayer->play();
    break;
}
});

[Kinesis]

@jsulm
Thanks . now the buttons are not linked any more. But my first problem is back . I can't play all videos . I can just play 1 video(last video) when I load 2 videos , I can't play any videos when i load more than 2 . I don't know what to do now . I am really stuck at this stage for 4 days. I really appreciate your help for helping until now.

[SGaist]

Are your buttons supposed to control all video players at once ? If so, then do it as I suggested and go it iterate through the vector of players and control them all.

If you want to control each player separately then you have have to create as many buttons as players.

[jsulm]

@Kinesis said in Media player not working for multiple videos:

I can just play 1 video(last video)

Sounds like you still use global mediaPlayer - do you?
Did you change the code as I suggested?

for(const QFileInfo & finfo: directory.entryInfoList()){
    QMediaPlayer *mediaPlayer = new QMediaPlayer(); // DO NOT USE GLOBAL mediaPlayer!
    mediaPlayer->setMedia(QUrl::fromLocalFile(finfo.absoluteFilePath()));
...
    connect(m_playButton, &QAbstractButton::clicked, [mediaPlayer]() {
        switch (mediaPlayer->state()) {
        case QMediaPlayer::PlayingState:
            mediaPlayer->pause();
            break;
        default:
            mediaPlayer->play();
            break;
    }
    });
...
    mediaPlayer->setVideoOutput(m_videoItem);
    m_mediaPlayer.append(mediaPlayer);

[jsulm]

@SGaist He creates one button for each video

[Kinesis]

@jsulm
I am not using mediaPlayer as global variable . Here is my updated code

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    ui->listWidget->setFlow(QListView::LeftToRight);
    ui->listWidget->setMinimumSize(760,350);
    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();
        //player = new QMediaPlayer(this,QMediaPlayer::VideoSurface);
        //player = new QVector<QMediaPlayer*>();
        //playlist = new QMediaPlaylist;
        // playlist->addMedia(QUrl::fromLocalFile(finfo.absoluteFilePath()));
        //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);
        scene->addItem(videoItem);

        mediaPlayer->setVideoOutput(videoItem);
        player.append(mediaPlayer);

        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));


        m_positionSlider = new QSlider(Qt::Horizontal);
        m_positionSlider->setRange(0, 0);
        connect(m_playButton, &QAbstractButton::clicked, this, &MainWindow::play);
        connect(m_positionSlider, &QAbstractSlider::sliderMoved,this, &MainWindow::setPosition);



        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();
}

bool MainWindow::isPlayerAvailable() const
{   QMediaPlayer *mediaPlayer = player[1];
    return mediaPlayer->isAvailable();
}



void MainWindow::play()
{
    QMediaPlayer *mediaPlayer = player[1];
    connect(m_playButton, &QAbstractButton::clicked, [mediaPlayer]() {
    switch (mediaPlayer->state()) {
    case QMediaPlayer::PlayingState:
        mediaPlayer->pause();
        break;
    default:
        mediaPlayer->play();
        break;
    }
});
}

void MainWindow::mediaStateChanged(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;
    }
}

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);
}

[J.Hilk]

@Kinesis
your still not doing what @jsulm suggested.

this

void MainWindow::play()
{
    QMediaPlayer *mediaPlayer = player[1];
    connect(m_playButton, &QAbstractButton::clicked, [mediaPlayer]() {
    switch (mediaPlayer->state()) {
    case QMediaPlayer::PlayingState:
        mediaPlayer->pause();
        break;
    default:
        mediaPlayer->play();
        break;
    }
});
}

is wrong and at the wrong place

delete that function all together

and in your loop replace

connect(m_playButton, &QAbstractButton::clicked, this, &MainWindow::play);

with

@jsulm said in Media player not working for multiple videos:

connect(m_playButton, &QAbstractButton::clicked, [mediaPlayer]() {
    switch (mediaPlayer->state()) {
    case QMediaPlayer::PlayingState:
        mediaPlayer->pause();
        break;
    default:
        mediaPlayer->play();
        break;
}
});

[jsulm]

@Kinesis You should think about the code you're writing and you should read what I'm writing more carefully. To be honest I'm tired of writing code for you and then see that you're not trying it but doing something else. The code you posted now is NOT what I suggested (again).

void MainWindow::play()
{
    QMediaPlayer *mediaPlayer = player[1];

Do you really think this code can work correctly? You always try to use SECOND player! How is it going to work?!
I post here my code once more, but for the last time:

for(const QFileInfo & finfo: directory.entryInfoList()){
    QMediaPlayer *mediaPlayer = new QMediaPlayer(); // DO NOT USE GLOBAL mediaPlayer!
    mediaPlayer->setMedia(QUrl::fromLocalFile(finfo.absoluteFilePath()));
...
    connect(m_playButton, &QAbstractButton::clicked, [mediaPlayer]() {
        switch (mediaPlayer->state()) {
        case QMediaPlayer::PlayingState:
            mediaPlayer->pause();
            break;
        default:
            mediaPlayer->play();
            break;
    }
    });
...
    mediaPlayer->setVideoOutput(m_videoItem);
    m_mediaPlayer.append(mediaPlayer);

[Kinesis]

@jsulm
I got it now . Sorry for wasting your time . Now I can play both videos . Do I need to replace the button state change into loop? Because button state(Icon) is not changing correctly and linking with other media players.

[jsulm]

@Kinesis You need to change all your other slots for mediaPlayer in the same way as play():

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;
    }
});

[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 .