How to make gstreamer give frames in RGB?

Question

linux

Hello. I have such a problem, I get frames from QMediaPlayer in the present method of a class inherited by QAbstractVideoSurface, everything is like in the examples and in feng shui. The problem is that QVideoFrame comes to me in YUV420p format and is not cast directly to QImage. What's even worse, even with the fastest methods it casts in RGB colors very slowly - an HD frame is about 40 ms, which is not even 25 fps in the end. And I really need RGB frames.
I understand that gstreamer is sitting under the soot. How can I make it throw frames in RGB?
Add. the question is how to make it stream faster than 25 frames per second from the code, i.e. set speed?
Ubuntu 15.10 x64 system.