Flip/Mirror QCameraViewFinder

For a project I'm working on I would like to show a live camera feed in a window. I have succeeded in this using a QCamera and a QCameraViewFinder. Now to take it one step further I would like to flip the camera feed horizontally or vertically or both. I have explored tree possible paths:

• Subclass QAbstractVideoSurface
• Implement a QAbstractVideoFilter
• Apply Shader

(I also failed at implementing all 3.)

As far as I know the first one can be done in pure c++ and the last two require QML. I would prefer not to use QML.

My question is this: Which is the best path to follow, and why? A code example would be terrific!

Much Love!

this worked for me:
> format.setScanLineDirection(QVideoSurfaceFormat::B ottomToTop);