Wiki/wiki-rtd/docs/wiki_faq/faq-other.md

FAQ: Emulation Requests

What are CD Image Formats and Disc Images?

Disc images are exact copies of physical discs. They allow you to play games without using the original discs, which helps preserve them.

Here we list some common file formats for disc images.

.iso (Optical Disc Image)

• The most common disc image format.
• Used for uncompressed disc images.

.nrg (Nero CD/DVD Image File)

• Created with Nero disc authoring software.
• Used for CD or DVD disc images.

.bin and .cue (Binary file and Cue sheet)

• .bin file contains the data or audio track.
• .cue file contains the structure details of the disc (you always load the .cue file).

.mdf and .mds (Media disk Image File and Media Descriptor File)

• .mdf file contains the CD or DVD data.
• .mds file contains the header and track information.

.chd (Compressed Hunks of Data)

• A lossless compression format originally developed for MAME.
• Compresses the contents of a disc image into a single .chd file.
• Supported by many systems and recommended for 3DO, Dreamcast, Sega CD, Neo Geo CD, PC Engine CD, PSX, PS2, and Saturn.