DI
From Console Research Wiki
The Nintendo GameCube/Wii use a custom disc interface called DI it is 25mhz, it carries data and audio streaming for AI(Audio Interface).
DI is custom as it doesn't follow the standard DVD-ROM interfaces such as SCSI, IDE/EIDE, ATAPI, SATA.
Audio Streaming on the disc is XA-DPCM compressed then it gets decoded by the Panasonic MN102 System Controller, then mixed by the Audio DSP then output to the AI aka audio interface.
