This is the universal standard for optical disc images. It is an uncompressed, sector-by-sector copy of an original disc (like a DVD or Blu-ray). Because it is completely uncompressed, it is massive, but it boasts 100% compatibility with almost every operating system, virtual drive tool (like Daemon Tools), and repacking script.

This article provides a step-by-step technical deep dive into converting CHD files back to ISO format for the purpose of repacking.

Note: Use createcd for CD-based games (PS1, Saturn, Dreamcast) and createhd for hard drive images.

A simple text script helps automate the process if you have multiple files to convert.

Replace <input_file>.chd and <output_file>.iso as necessary.

You want to modify or "hack" the game files (e.g., applying English translation patches).

chdman extractcd -i game.chd -o game.cue

Navigate to that folder in your command prompt or terminal.

To perform this conversion, use the extractcd command:

chdman extracthd -i "Silent Hill.chd" -o "Silent Hill.iso"

To convert files back to ISO or BIN/CUE format, you must use chdman , a command-line utility included with the MAME emulator . 1. Extract a Single CHD to ISO