I think the original Gamecube component cable is overpriced, so I cloned it. =) Github repository here
. Some random factlets because I'm too lazy to write a coherent post after typing all the READMEs in the repo:
The project linked above is basically a clone of the original component cable using only information that is already available on the net
and some of my own observations on a logic analyzer. The board can output analog RGB (both CSync and HV-Sync available) or Component video. While I haven't calculated an actual BOM cost for the parts, it should be MUCH cheaper to manufacture than the current price for the original cable. The downside is that as far as I know there is no source for the original plug, so it has to be mounted internally in the Gamecube.
No, I won't be selling this. Build your own or find someone who builds it for you - it's an open source project after all. I made the mistake of offering kits for another of my projects once and that required far more of my time than I'm willing to spend. Fully-assembled boards aren't an option at all for me as the local laws require a lot of paperwork, certifications and money when you want to bring your own electronic devices into the hands of end-users.
HDMI is possible and works on my devboard, but that version currently suffers from featuritis and lack of motivation (and maybe skills) to design a PCB for it. If anyone can locate (or provide) a source for simple, cheap Spartan 6 FPGA boards with an HDMI output connector on them I can probably port the code to it.
The board does not handle audio at the moment, although the pins for it are connected to the FPGA. Fun fact: At least the PAL Gamecube I have hear uses the wrong audio sampling rate. The correct rate would be 54MHz divided by 1125 (48000 Hz), but I measure exactly 48042.8Hz or 54MHz divided by 1124. The difference is not noticable on the analog outputs, but I suspect that the SPDIF mod the GC that uses an external 12.288MHz crystal for its SPDIF chip has faint clicks in its output (or slight distortions).
Based on a few preliminary measurements, the Wii seems to use the same video data format internally, but with 1.8V levels instead of 3.3V. Since the Wii already has a component output, connecting this board to it probably isn't worth the hassle unless you've fried our video output. It also seems that the Wii internally transports audio using I2S, so why isn't there an SPDIF mod for it yet?
If you look at the board another way, it's an FPGA with a few input lines (12 on the connector plus a few pads with spare pins) and a video DAC. This means that is someone writes the code for it, it could also be used to generate RGB or component output signals for other consoles that use 3.3V digital video signals internally. The one that I'm thinking of is the N64 - but this is only a "possible in theory, but someone needs to do it first" situation.
Linedoubling would be possible with a larger FPGA (available with the same footprint, about 2-3 USD more expensive), but I'm not sure if it's worth it since most non-progressive Gamecube games are 480i/576i and the memory in the FPGA is only big enough to hold a single line, not a complete field that you would need to do at least half-proper deinterlacing. (and I also haven't figured out a way to generate "good" 480p timing from a 480i input yet)