Paused playback in Qt window blanks out when losing focus or resizing smaller

philippe renon philippe_renon at yahoo.fr
Wed Sep 28 12:45:24 UTC 2016


Hi,

You'll need to expose the overlay in every Qt paint event to fix this issue.
void VideoWidget::paintEvent(QPaintEvent *event)
{
    // qDebug() << QString("VideoWidget::paintEvent - %0").arg((long)winId());
    if (overlay) {
        overlay->expose();
    } else {
        QWidget::paintEvent(event);
    }
} 

    Le Mercredi 28 septembre 2016 0h00, doubledw <dwood at mak.com> a écrit :
 
 

 I am sending video playback to a Qt widget using
gst_video_overlay_set_window_handle (Windows VC10-64bit, Qt 4.8.7).
Everything is working smoothly except when I pause playback

        gst_element_set_state(myPipeline, GST_STATE_PAUSED);

After the pause, the view goes blank if I move focus away from the Qt widget
or resize the view smaller. If after going blank, I resize the view bigger,
the paused frame will reappear.

Is there any callback that I can register or signal that I can catch with
gstreamer to control when a paused image is rendered?

I have tried overriding the various Qt events to prevent the widget from
repainting over the paused image. Even when Qt repainting is short-circuited
the view becomes blank. Based on suggestions from this mailing list, I have
also tried performing gst_video_overlay_expose to re-render the paused
image. However, when I trace the execution after the view has gone blank and
I do another resize smaller, I see where I perform the
gst_video_overlay_expose and the image is re-rendered. The execution then
continues outside of my application's control and something else blanks out
the view again.

Thanks for any help you can provide.




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