No video and only audio output when restarting QMediaPlayer's media

Question

I'm currently developing an application using Qt 5.15.2 on Ubuntu 22.04 and encountering an issue with QMediaPlayer in a video playback context. I've provided my code below for reference.

The application successfully plays, pauses, and resumes video playback.

However, when a video reaches its end and I attempt to restart it, only the audio resumes — the video display does not.

This issue occurs specifically after the video has completed playing, and I try to replay it.

// videoPlayer function
void MainWindow::videoPlayer() {
    player = new QMediaPlayer(this);
    videoWidget = new QVideoWidget(ui->widget_video);
    player->setVideoOutput(videoWidget);
    player->setMedia(QUrl::fromLocalFile("/home/ubuntu/Desktop/test.mp4"));

    QVBoxLayout *layout = new QVBoxLayout(ui->widget_video);
    layout->addWidget(videoWidget, 0, Qt::AlignCenter);
    layout->setMargin(0);
    layout->setSpacing(0);
    ui->widget_video->setLayout(layout);
}

// Button click event handler
void MainWindow::on_pushButton_video_status_clicked() {
    switch (player->state()) {
    case QMediaPlayer::PlayingState:
        player->pause();
        break;
    case QMediaPlayer::PausedState:
        player->play();
        break;
    case QMediaPlayer::StoppedState:
        player->setPosition(0); // Reset to start
        player->play();
        break;
    default:
        player->play();
        break;
    }
}

I've tried resetting the media player's position and reinitializing the media source, but the issue persists. The audio resumes as expected, but the video display remains blank.

How can I solve this?

Answer 1

I've now resolved this problem by directly placing the QVideoWidget in the parent widget, without using a layout. Here's the updated code:

void MainWindow::videoPlayer() {
    player = new QMediaPlayer(this);
    video = new QVideoWidget; // Create a new QVideoWidget

    // Set the size and position of the QVideoWidget
    video->setGeometry(5, 5, ui->groupBox_videoPlayer->width() - 10, ui->groupBox_videoPlayer->height() - 10);
    video->setParent(ui->groupBox_videoPlayer); // Set the parent widget

    player->setVideoOutput(video); // Set the video output
    player->setMedia(QUrl::fromLocalFile("/home/ubuntu/Desktop/test.mp4")); // Load the media file

    video->setVisible(true); // Make the QVideoWidget visible
    video->show(); // Show the QVideoWidget
}

This change allows the video widget to be placed directly inside the parent widget, avoiding issues that arose from using a QVBoxLayout.

However, I couldn't understand why I was encountering problems when I used

QVBoxLayout.