Just for the record.
More than a year ago I started a similar project base on the FPGA. It outputs directly HDMI and VGA 576p signal (exactly doubled PAL timing, thus no tearing).
I have no time to work on it, because I'm totally overhelmed by my day work projects, so I'd like to release it as opensource. But I need to coopoerate with someone that would help me to setup all the things like GIT for that. Any volunteers?
Current status is:
Standard modes: done
hires modes: done
GTIA modes: done (with a small bug)
PMGS: broken and unfinished
pallete: done (borrowed from altirra for now)
GTIA logic: NO (has to be paired with a real GTIA fro now)
Hardware design: NO (currently developed on the Scarab Spartan6+, but the final design targetted to the Spartan3)
The project is acutally more a proof of concept than a real product. It is written in VHDL (Xilinx ISE project) and it a mashup of various pieces of the code from a various opensource products, examples, etc.
Thenically it uses the FPGA only without any additional chips except 5V level shifters. The HDMI/DVI is trasmitted directly from the FPGA, same for VGA (+ resistor RGB DAC) and only the internal FPGA RAM is used for the buffers.