GCVideo is an open-source project 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 , created by ikorb.
This Project relies on building your own board (a lot of work), but instead you can pick a few of the ready-made adapters and install / use them.
Warning: This particular mod requires lots of internal modifications, and is not for the average user. It is incredibly difficult. If you don’t have really good soldering skills, you should stick to one of the Plug And Play Adapters.
You can find more info on the GCDual page.
Plug And Play Adapters
All of these adapters plug directly into the digital out port in the gamecube, meaning they aren’t compatible with the DOL-101 model without some more difficult hard mods
You can find more information on the Plug and Play page.