Popular File formats for CD Emulation

In this article we’ll talk about the most common formats used for representing CD data for emulators. If you’re confused about cue vs bin vs iso vs chd, this is the article for you.

CUE and BIN files

These files originate from thinking about CDs as holding a collection of audio tracks. A .cue is sort of like a table of contents, and .bin files are the raw data of the tracks. A cue file refers to data from one or more bin files.

To use cue and bin files with an emulator that supports them, you will typically need all the cue and bin files in the same directory. The cue file has references to the bin file names, so be careful not to rename them.

ISO files

ISO files represent the complete data of a disk. ISO files can be written to a physical CD, and contain all the information required to do so. These are based on the ISO 9660 format, which describes how to put files on a CD.

ISO files are not compressed. Which brings us to…

CHD files

CHD is a format created by the MAME team. CHD stands for “compressed hunks of data”, and is a way of compressing and storing all the data for a game. A CHD file can be created from a cue and all the bins.

CHD files are also compressed. Since game data has a lot of regular structure, lossless compression algorithms are often able to store the same exact data in less space.

CHD files can be created using the free tool “chdman” from the MAME project. We are also working on a CHD creator that runs in the browser, to make this file format easier to use.