I recently downloaded the original Safecracker game from 1997. After extracting the game I was a little confused… there was a .cue, but the accompanying .bin file had the format .bin.ecm. I needed to find what this .ecm compression was all about:
“ECM is an acronym for Error Code Modeler. Files that contain the .ecm file extension normally store modified disk image copies. User’s commonly use this file format to create back-up copies of their computer hard drive’s contents.
Unlike many disk image formats, the ECM file format allows for better file compression than the typical archive file format. This saves on disk and drive space when copying a hard drive into the ECM file format.
The Cmpro software application has also been known to use the .ecm file suffix. These ECM files contain example files that are used by the Cmpro software.”

“ECM stands for Error Code Modeler , it compresses files and save huge amount of space, most of the CD/DVD have unnecessary EDC/ECC data in them and takes lots of space on the drive, ECM only adds the data in the compress file, and thus the file size changes, the compression size depends on unnecessary EDC/ECC data on the CD. Compressing a CD image to ECM is easy, just open the CD image file into your favorite compression program and save the file as [filename.bin].ecm, just add ECM at end.”

To convert/uncompress the .ecm file we can convert it using the following:

sudo apt-get install ecm
ecm-uncompress foo.bin.ecm foo.bin