strygo / gcvideo

GameCube Digital AV converter

GCVideo

GCVideo is a small series of FPGA boards and VHDL projects capable of converting the GameCube's Digital Video port signals to standard video signals without using the custom chip in the original component video cable. There are currently VHDL projects for multiple FPGA boards, including a Gamecube-to-DVI version for the KNJN Pluto IIx-HDMI and a Gamecube-to-Component/RGB version for a board called GCVideo Lite which is also documented in this repository. GCVideo Lite has also been adapted to be used as an RGB DAC for the Nintendo 64.

The schematics and layout are in the Hardware directory and the HDL projects are in the HDL directory. Each directory should contain README.md files with further information.

Mini-FAQ

1. I want one, how much is it?
   I do not sell any hardware. Since this is an open-source project, other people will probably offer ready-made boards or modding services.

   GCVideo-DVI is based on a readily-available, commercial FPGA development board, so you could just buy that, flash it and install it yourself (or find someone to do it for you).

2. But why don't you just sell it?
   Building hardware to be sold is a lot of work and requires much time that I'd rather use for something more interesting. Furthermore, the local laws require quite a bit of paperwork and investment to legally sell electronic devices that you build and I'd prefer not to deal with all of that.

3. You said your prototype came from OSHPark, so you have at least three boards. Can't you sell me one of them?
   No, they're all accounted for already.

4. Why did you use that weird Video-DAC, it's a non-stock part at Digikey!
   It wasn't when I designed the board some months ago... Instead it was the cheapest 24-bit video DAC available. It shouldn't be hard to adapt the design to a different DAC as long as it has 24 bit parallel input and a single-pumped clock. For YPbPr output, the DAC also needs to be able to generate a small offset on the Y line so that syncs can be generated below the blanking level.

5. Uh, it says XO2-256 in the schematic, but XO2-640 in the BOM. Which is the correct one?
   The original plan was to use an XO2-256, but adding the color space conversion for RGB output increased the size of the design too much. It was left as an XO2-256 in the schematic to ensure only pins available on that chip are used, so a slightly cheaper Component-only version can be built.

6. What about line-doubling?
   GCVideo Lite (the analog version) uses the smallest FPGA that could fit everything needed, but this chip does not have enough BlockRAM available to generate a line-doubled picture. It could be updated by using a larger, footprint-compatible FPGA, but since 480i/576i are well-supported on component inputs and 240p/288p are rarely used by Gamecube titles this has not been attempted yet.

   GCVideo DVI fully supports line-doubling and can also overlay scanlines on the line-doubled picture if desired.

Licence

Copyright (C) 2014-2020, Ingo Korb <[email protected]>
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice,
   this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright notice,
   this list of conditions and the following disclaimer in the documentation
   and/or other materials provided with the distribution.

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