Using the camera from QtMultimedia has a problem that it does not consistently produce an actual video feed.
A percentage of the times we get a black feed.

Please look at the attached tarball on related QTBUG-109168 which has a runnable example to allows you to reproduce it using pure QML.

Problem: Turning on and off the camera repeatedly will sometimes just create a black feed.

While the example, on my test device, never gives an error, on the C++ side I've often seen it error with "Device in use". Which created a chuckle as the one using it is this widget.

My expectation is that the camera produces a valuable feed every single time, especially when no error state is hit.