Change a video frame by frame with QtMultimedia?

[VincentG]

I've recently start learning PyQt5 to make a small video player that fit to my needs.
I can play a video in a QMediaPlayer of QtMultimedia and display it in a QVideoWidget().

But there is something I can't do yet is change just one frame of the video to the next or the previous one.
The only property I get about it is the position that I can set with setPosition(). But it's in milliseconds and not in frames. Is there a way the set the position to a specefic frame or to get the framerate to convert the millisecond position into the desired frame?

Thanks!!