: A lossless compression format originally developed for the MAME arcade emulator. It is widely considered the best format for PS2 emulation because it perfectly preserves game data while significantly reducing file size.

The Ultimate Guide to PS2 CHD ROMs: Exclusive Benefits and Best Games

Once the tool finishes, you will see new .chd files sitting alongside your old files. You can safely delete or archive your original bulky ISO files and move your shiny new CHD files straight to your emulation directory. Using CHD Files in Modern Emulators

Create a batch file or use the terminal to run: chdman createcd -i "game.iso" -o "game.chd" (for CD-based games)or chdman createdvd -i "game.iso" -o "game.chd" (for DVD-based games).