Using QPixmap from converted QVideoFrame in graphics scene on android

Clemens 69er

Hello,

I have written a simple test UI that shall display a pixmap from a converted video frame within a QGraphicsView. On Ubuntu everything runs fine - the frames taken from a WebCam are shown correctly. But when it runs on Android, after some frames an out-of-memory happens.
Here's the regarding method:

void MainWindow::handleFrame(QVideoFrame frame)
{
    qDebug("enter handle frame");
    if (frame.isValid())
    {
        QVideoFrame cloneFrame(frame);
        if (cloneFrame.map(QAbstractVideoBuffer::ReadOnly))
        {
            QImage image = qt_imageFromVideoFrame(cloneFrame);
            if (image.byteCount())
            {
                if (!m_scene)
                {
                    m_scene = new QGraphicsScene(this);
                    ui->graphicsView->setScene(m_scene);
                }
                m_scene->addPixmap(QPixmap::fromImage(image));
            }
            else
            {
                qDebug("converted image empty!");
            }
            cloneFrame.unmap();
        }
        else
        {
            qDebug("frame could not be mapped");
        }
    }
    else
    {
        qDebug("frame invalid!");
    }
}

A hint: when I comment out m_scene->addPixmap(QPixmap::fromImage(image)); no exception occurs, although the images are still mapped and converted!
So the question is - why does it happen on Android only? Do I have to take care manually for the pixmap allocated memory?

Hope someone can help out here :)

SGaist

Hi and welcome to devnet,

From the looks of it, you are leaking pixmap object each time there's a new QVideoFrame. Why not keep a pointer on the QGraphicsPixmapItem created the first round and then only update it ?