ECM (Error Code Modeler) lets you prepare CD image files (such as BIN, CDI, NRG, CCD, or similar) so that they'll compress far better in programs such as WinRAR.
If you emulate playstation games or any ROM that use ISO's or CD images, then you know how important ECM tools are because everyone uses ECM to compress their ROM images.
USAGE:
ecm FILE.bin
unecm FILE.bin.ecm
