To convert a (Compressed Hunks of Data) file back to an format, you will primarily use , a command-line tool that is part of the What is CHD?
CHD is a lossless compression format widely used in emulation (PS1, PS2, Saturn, Dreamcast) to save disk space without losing data or performance. Because it is highly specialized, standard tools like WinRAR or 7-Zip cannot open or convert it. Step-by-Step Conversion 1. Obtain CHDMAN The easiest way to get the tool is to download the latest MAME release and extract chdman.exe from the folder. Alternatively, many community sites like RetroGameCorps
provide "CHD helper" packs that include the executable and batch scripts. 2. Perform the Conversion
You can convert files using the Command Prompt or by creating a simple batch script. Using Command Prompt: chdman.exe in the same folder as your Open Command Prompt in that folder. chdman extractcd -i "YourGame.chd" -o "YourGame.cue" Use code with caution. Copied to clipboard Note: For CD-based games, this will generate a file. You can then use tools like to convert that BIN/CUE into a single ISO if needed. Using a Batch Script (Bulk Conversion):
If you have multiple files, create a new text file, paste the following, and save it as convert.bat
for %%i in (*.chd) do chdman extractcd -i "%%i" -o "%%~ni.cue" pause Use code with caution. Copied to clipboard
Run this file, and it will automatically process every CHD in the folder. Key Considerations Resulting Format: Most conversions result in rather than a raw convert chd to iso
. This is because many disc-based games (like PS1) use multiple tracks that a standard ISO cannot store. Compatibility:
Only convert back to ISO/BIN if your specific emulator or hardware (like the Satiator for Saturn ) does not support CHD.
Since CHD is lossless, the files you extract will be bit-perfect copies of the original data.
steps to merge the resulting BIN/CUE into a single ISO file? CHDMAN - Recalbox Wiki
If CHD is so efficient, why would anyone convert backwards? Here are the most common reasons:
.chd file to a CD-R. You must have the original ISO or BIN/CUE.Step 1: Download MAME Tools
Do not download random "CHD converters" from sketchy websites. Go to the official MAME development site (or a trusted repository like Progetto-SNAPS) and download the latest mame-tools.zip. Inside, you will find chdman.exe. To convert a (Compressed Hunks of Data) file
Step 2: Extract the Tool
Place chdman.exe in a folder where you keep your ROMs or games. For simplicity, create a folder on your desktop called CHD_Convert.
Step 3: Open Command Prompt
Navigate to your folder. Click the address bar in File Explorer, type cmd, and press Enter. This opens a command prompt directly in your working directory.
Step 4: Run the Extract Command
The syntax for converting CHD to ISO is:
chdman extracthd -i "inputfile.chd" -o "outputfile.iso"
For example, if you have a file named Metal_Gear_Solid.chd, type:
chdman extracthd -i "Metal_Gear_Solid.chd" -o "Metal_Gear_Solid.iso"
Step 5: Wait for Verification
chdman will read the CHD file, verify the CRC checksums, and write the raw ISO data. A progress bar will show you the speed. Once it reaches 100%, your ISO is ready.
Before diving into the conversion process, it is critical to understand what a CHD file is. Burning to Physical Media: You cannot burn a
Originally developed by the MAME (Multiple Arcade Machine Emulator) team, CHD was designed to compress hard drive and CD-ROM images from arcade machines. Unlike ZIP or RAR, which compress files individually, CHD compresses the raw sector data of a disc. It uses advanced algorithms to identify redundant data, effectively shrinking a 700MB CD-ROM to as little as 100MB without losing a single bit.
Why would you want to convert CHD to ISO?
The conversion process involves the extractcd command within the chdman utility.
for f in *.chd; do chdman extract -i "$f" -o "$f%.chd.iso"; done
End of Report
In the world of video game emulation and disc-based archival, file formats are a constant topic of discussion. Two of the most common formats you will encounter are ISO and CHD.
While ISO is the industry standard for raw disc images, CHD (Compressed Hunks of Data) has risen in popularity due to its lossless compression capabilities. However, there comes a time when every retro gamer or IT professional needs to convert CHD back to ISO. Whether your emulator doesn't support CHD, you need to burn a disc, or you require raw file access, this guide will walk you through everything you need to know about converting CHD to ISO.