You can subclass QQuickItem to create a custom item that you can then use in a Qt Quick scene. In this subclass you can use gstreamer to render a video. So, yes, you can use QQuickItem here. Simply speaking, this is what the Qt Quick Video Item does, too. But please don't ask me how to use gstreamer directly because I have no idea :-)
I'm very sorry for the so late reply, but I just had some urgent problems, and I had to leave this forum and work with another things.
I see that you shared your advice and sample for this issue as you promised.
So I want to thank you for this!
Unfortunately, I had to do other things, but I think that you helped other users (including chaudhry) to solve this not simple task! :)
Sorry and thank you one more time!