chdman createcd -i "game.cue" -o "game.chd"
chdman.exe createcd -i "game.iso" -o "game.chd" -c zstd
Enter chdman.exe . This essential command-line utility, developed by the MAME development team, allows you to convert these bulky files into the format. This process significantly reduces file sizes—often by 50% or more—without losing any data (lossless compression).
| Parameter | Effect | Best For | | :--- | :--- | :--- | | -c zstd | Uses Zstandard compression (modern, faster decompression) | PS2, PSP | | -c lzma | Slower but highest compression ratio | Arcade CHDs, CD-based games | | -h 2048 | Sets hard disk sector size (default is 512) | Dreamcast GDI rips | | -f | Force overwrite of output file | Batch re-encoding | download chdman.exe
While originally built for arcade machine roms, the CHD format has become immensely popular for optical disc images (like .bin/.cue , .iso , and .gdi ). Why Use CHD Format?
Similarly, to extract all CHD files in a directory:
Common for PlayStation 1, Sega CD, and Sega Saturn. (Ensure you target the .cue file, not the .bin ). .gdi: Standard for Sega Dreamcast. .iso: Standard for PlayStation 2 and PlayStation Portable. What emulators support .chd files? Sony PlayStation 1: DuckStation, PCSX ReARMed, Beetle PSX. Sony PlayStation 2: PCSX2. Sega Dreamcast: Flycast, Redream. Sega Saturn: Mednafen, Yaba Sanshiro. PC Engine / Sega CD: Genesis Plus GX, Beetle PCE. Troubleshooting Common Errors Error: "Requires input file" or "Open failed" chdman createcd -i "game
Create a new text file in that same folder and paste a command script (like those found on the Recalbox Wiki ). Rename the text file to convert.bat .
Hunk size refers to how the data is split for compression. The default hunk size ( -hs 2048 ) works well for most applications, but you may want to adjust it for specific use cases like the PPSSPP emulator.
Once you have chdman.exe , you need to get it ready for use. There are two main ways to set it up: a simple copy-paste method for occasional use, or adding it to your system PATH for command-line convenience. | Parameter | Effect | Best For |
: You can copy just chdman.exe to any other folder where you store your ROMs for easier access. How to Use chdman.exe for ROM Conversion
If you need help setting this up, let me know which emulator or device (e.g., RetroArch, Raspberry Pi) you're using, and I can give you specific steps. Share public link
: Run the installer or use a tool like 7-Zip to extract the contents.
Here are some additional tips and tricks to help you get the most out of CHDMAN.EXE:
Check that your file names match exactly. If you are converting a .cue file, open it with Notepad and ensure the filenames listed inside the text file match the actual names of your .bin files.
