Converting CHD to ISO — Guide

What CHD and ISO are

• CHD (Compressed Hunks of Data): A compressed disk-image format used by MAME/MESS to store hard drives, CD images, and other media efficiently while preserving sector-level metadata.
• ISO: A standard uncompressed disc image format for optical media (CD/DVD/Blu‑ray) that is widely supported by emulators, mounting tools, and burning software.

Verification and preservation recommendations

• Keep the original CHD as the archival master because it preserves compression, metadata, and subchannel data.
• Store checksums (SHA-256) for both CHD and generated ISO.
• Document conversion provenance: date, tool versions (chdman --version), options used, operator identity, and checksums.
• If long-term use expects ISO only, store both the ISO and the original CHD to enable future re-processing.

Method 1: Using Command Line (Windows, macOS, Linux)

This is the most direct and professional method.

A standard "raw" sector-by-sector copy of an optical disc. While widely compatible, it lacks the built-in compression and metadata features found in CHD. 2. The Conversion Process: The industry-standard tool for this conversion is , a command-line utility bundled with the

Batch convert all CHD in folder (Linux/macOS/WSL)

for f in *.chd; do chdman extract -i "$f" -o "$f%.chd.iso"; done

Main script

if [[ $# -eq 0 ]]; then echo "Usage: $0 <chd_file(s)>" echo "Examples:" echo " $0 game.chd" echo " $0 .chd" echo " $0 /path/to/chds/.chd" exit 1 fi

sudo apt install mame-tools  # Debian/Ubuntu