Unfortunately there not much people outside Brcm can do to help. You need access to the GPU code, and quite a lot of knowledge of how the camera ISP hardware works. It's the second that is the problem, as we have the camera register settings, but my efforts so far result in no frames coming back.
I'm hoping to look at this stuff over the next week when my boss gets back (he's the real expert on this stuff), but he may tell me to do something else!
Principal Software Engineer at Raspberry Pi (Trading) Ltd.
Please direct all questions to the forum, I do not do support via PM.