Wrong colors when using Phonon GStreamer in QGraphicsView

When using Phonon with the GStreamer backed on linux inside QGraphicsView, the colors are wrong, it is like being in BGR instead of RGB.
The problem can be fixed by swapping the QImage that is created for every frame (see attached patcg), but I somewhat doubt this is the correct fix, as
a) it works if it is not in QGV
b) similar code is in qglrenderer.cpp, but that doesn't seem to be used even if the QGV widget is a QGLWidget

Luckily and strangely, even with the swapping playing works e.g in Dragon Player from KDE as it is supposed to be.

See the solution, two example images, a testcase and an example movie (but for me happens for every movie file)