The ECM extension is given to files that are used by Error Code Modeler. These files are used to store compressed disk images. Often this format was used to create images of video games developed for the Sony PlayStation 1. The ECM image is a format that is additionally modified by removing redundant information that does not affect the correct recovery of the disk. This solution saves space from 15 to 20%.

Error Code Modeler was developed by Neil Corlett and it is a tool with a high compression ratio when creating disk images.