[Development] New Qt Multimedia

[Jason H]

> > If it matters: I disclaim any copyright for the attached files.<barcodevideoprobe.cpp><barcodevideoprobe.h>
>
> Thanks for the snippet. I think this should be perfectly doable. Connect to the signal, then map the QVideoFrame and copy out the Y channel.


One ask that may not be captured anywhere: currently, it is impossible to have a QML Camera and not start it.

If I could request,
1. a way to probe hardware without activating it
2. a way to have a QML Camera without getting frames from it, that is to set `active: false` is the default. Currently, there is not even active property. We have to do a Component.onCompleted: stop() which has already triggered the permission dialog. This was ok in the past, but the trend and proper usage is to request permission only when it is needed.