QGraphicsVideoItem doesn't render QCamera output, while QCameraViewfinder does without problems

[fama_lab3d]

As the title says, I need to use a QGraphicsScene to render points (ellipses) on top of the QCamera output.
So what I've done? I've created a scene, added a QGraphicsVideoItem and setted that item as the QCamera viewfinder.
The problem is that it never renders the camera output.
I tested with a QCameraViefinder and worked flawlessly, on the first try.
The strange thing is that I've did it in the past, so I don't understand what kind of setup the QGraphicsVideoItem requires.

Do I need to set the item as the viewfinder before it's added to the scene?
Do I need to be sure it's painted at least once before setting it as the viewfinder?

At the moment I'm simply doing this:

void worker::set_viewfinder(QGraphicsVideoItem *video_item) // doesn't work
{
    camera->stop();
    camera->setViewfinder(video_item);
    camera->start();
}
void worker::set_viewfinder(QVideoWidget *video_item) // works
{
    camera->stop();
    camera->setViewfinder(video_item);
    camera->start();
}

[SGaist]

Hi,

Which version of Qt are you using ?
On which platform ?
The class name Worker suggests it could be doing things in a different thread, is it the case ?
Do you have the same issue with a simple view, scene and item ?