CDI is the essential format if you intend to burn games to disc for use on original hardware (Rev 0 or 1 consoles). Comparison of Compression Formats Compression Type Best Use Case GDI None (Raw) Archive-quality 1:1 rips; GDEMU CHD Lossless Zlib/LZMA General Emulation (Flycast, Redream) Yes CDI Lossy (Asset stripping) Burning to physical CD-Rs Optimizing Your Library
While GDI is a 1:1 "raw" dump of a 1GB GD-ROM, the format is a unique, "hand-crafted" compression method. dreamcast roms highly compressed exclusive
You can convert raw GDI files to CHD using tools like CHDMAN (available via Internet Archive ) or graphical interfaces like NAM DHC for a more user-friendly experience. The "Highly Compressed" Exclusive: CDI vs. GDI CDI is the essential format if you intend
CDI files were originally designed to fit 1GB Dreamcast games onto standard 700MB CD-Rs. The "Highly Compressed" Exclusive: CDI vs
This format is natively supported by top-tier emulators like Flycast and Redream .
To achieve this "high compression," creators often down-sample audio, reduce movie bitrates, or remove "dummy data".