What Is an ECM File?

How to open, edit, and convert ECM files

A file with the ECM file extension is an ECM Disc Image file, or sometimes called an Error Code Modeler file. They are disc image files that store content without error correction codes (ECC) or error detection codes (EDC).

Shaving off ECC and EDC saves on download time and bandwidth since the resulting file is smaller. The point is to then compress the file with a general compressor, like RAR, or another compression algorithm, to reduce the file size even more (they might then be named something like file.ecm.rar).

Like ISO, ECM hold other information in an archive format, usually to store files like BIN, CDI, NRG, etc. These are often used to contain compressed versions of video game disc images.

You can read additional information on how the ECM Disc Image file format works on Neill Corlett's website.

The Cmpro Examples file format might use the ECM file extension, too, but there isn't much information on it.

How to Open an ECM File

ECM files can be opened with ECM, a command line program by Neill Corlett, the developer of the format. See the How to Use the ECM Program section below for more information.

ECM commands

ECM files also work with Gemc, ECM GUI, and Rbcafe ECM.

Since the file can be compressed to an archive like a RAR file to save on hard drive space, it might first have to be decompressed with a file zip/unzip utility—our favorite is 7-Zip.

If the data inside the ECM file is in the ISO format, see How to Burn an ISO Image File to a CD, DVD, or BD if you need some help getting it on a disc. See Burning an ISO to USB for help properly installing it to a flash drive.

ECM files that aren't disk image files might be able to open with a simple text editor like Notepad in Windows, or something more advanced from our Best Free Text Editors list. If the entire file isn't text-only, and only some if it is viewable, you might still be able to find something useful in the text about the type of software that can open the file.

How to Use the ECM Program

Encoding (creating) and decoding (opening) an ECM file can be accomplished with Neill Corlett's ECM program mentioned above. It's a command line utility, so the whole thing runs in a Command Prompt.

To open the ECM portion of the tool, extract the contents out of the cmdpack(version) ZIP file downloaded through his website. The program you're after is called unecm.exe, but you have to access it through a Command Prompt.

cmdpack extracted files in Windows 10

The easiest way to do this is to drag the ECM file directly onto the unecm.exe program to extract the image file out of it. To make your own ECM file, just drag the file you want encoded onto the ecm.exe file.

To do this manually instead of with drag and drop, open Command Prompt (you might need to open an elevated one) and then navigate to the folder that holds the ECM program. The easiest way to do this is to first rename the folder you extracted above, to something simpler like cmdpack, and then enter this command:

cd cmdpack

This command is to change the working directly to the folder where the ECM program is stored. Yours will look different depending on where the cmdpack folder is located on your computer.

These are the commands you're allowed to use:

To encode:

ecm cdimagefile
ecm cdimagefile ecmfile
ecm e cdimagefile ecmfile

To create an ECM file, enter something like:

ecm "C:\Others\Games\MyGame.bin"

In that example, the file will be created in the same folder as the BIN file.

To decode:

unecm ecmfile
unecm ecmfile cdimagefile
ecm d ecmfile cdimagefile

The same rules apply for opening/decoding the ECM file:

unecm "C:\Others\Games\MyGame.bin.ecm"

How to Convert an ECM File

The tutorial at StramaXon provides an easy way to convert ECM to BIN. The download mentioned on that site is in the RAR format, so you'll need a program like PeaZip or 7-Zip to open it.

Once you have the ECM file in the BIN format, you can convert BIN to ISO with a program like MagicISO, WinISO, PowerISO, or AnyToISO. Some of these applications, like WinISO, can then convert ISO to CUE if you want your ECM file to ultimately be in the CUE format.

File Still Doesn't Open?

Some file formats share some or all of the same file extension letters, but it doesn't mean that they're in the same format. This can be confusing when trying to open your file because it might not actually be an ECM file...double-check the file extension to be sure.

For example, you might be confusing it with an EMC file, which is a Striata Reader Encrypted Document file. You can open an EMC file with Striata Reader.

EMM is similar. Files using that extension are documents created and used by MindMaple.

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