Atari hardware project idea

A few days ago, I started thinking about how difficult it’s becoming to find a good monitor for my Atari, especially one that I can easily bring with me on demo parties and such.

Then it occurred to me that my CosmosEx that is mounted inside the ST have a Raspberry Pi inside it, with both an HDMI and a composite video out. What it also have is a high speed connector for camera hardware, capable of streaming HD video in realtime. What I realised is that, with some custom hardware with an FPGA one could get the video signal directly from the shifter and feed it to the Pi in realtime. All it would take is a pretty simple program on the Pi to display the ST:s video output on any screen.

After studying the schematics for the STe and ST, the respective shifter seems to output 4bit (for STe, 3bit on ST) digital RGB values that is then turned into an analog signal. Hooking into these pins should be fairly simple, and together with the pixel clock and the sync signals, an FPGA should be able to convert the color data and send it as an image through the CSI-2 port to the Pi.

My problem is that I know very little of FPGA and hardware development. I would like to be able to build this by myself, but if some pro could help out, that would be awesome.