Tools like chdman use lossless compression. This means that while the file size on your SD card might drop from 1.1GB to 600MB, every single bit of game data is identical to the original when it is decompressed on the fly during play.
While raw .gdi (Gigabyte Disc Image) files are the "gold standard" for accuracy, they are often messy, consisting of dozens of small files that can lead to SD card fragmentation. dreamcast+games+highly+compressed+better
When it comes to building a Sega Dreamcast library for modern emulators or Optical Drive Emulators (ODEs), the choice of file format is more than just a matter of disk space. For years, the community struggled with bloated files and compromised CDI rips. Today, however, "highly compressed" no longer means "low quality." Tools like chdman use lossless compression