CHDBOY

CHDBOY converts disc images (BIN/CUE, GDI, ISO) into compressed CHD archives on Android. CHD (Compressed Hunks of Data) is a lossless format that shrinks a disc image substantially while preserving it byte for byte, so your game backups take far less space with no loss of data.

Status: Google Play submission candidate. The app is currently free. If you enjoy it, please consider supporting future releases when they arrive on the Play Store.

Highlights

• Purpose-built CHD writer: A native CHD v5 encoder written for this app, not a port of a desktop command-line tool. Hunks are compressed in parallel across every core, identical hunks are stored once, and zstd does the compressing.
• Nothing is copied: Source and output both live in the folder you pick, reached through Storage Access Framework descriptors. A 40 GB image needs 40 GB of free space, not 80, and the conversion starts immediately instead of after two full copies.
• Real CD support: .cue and .gdi produce proper CD-format CHDs with per-track metadata, subcode separation, and recomputable ECC dropped — the same layout chdman createcd writes, verified against libchdr.
• Duplicate CHD protection: Images that already have a matching .chd in the folder are skipped.
• Background-friendly: Accept notification permissions so conversions can finish even when the app is closed.

Getting Started

1. Install the APK or build from source (see below).
2. Use the Storage Access Framework picker to select the folder that contains your BIN/CUE, GDI or ISO files (no legacy storage permission required).
3. Every convertible image in that folder is queued; the finished .chd files are written back into the same folder.
4. Wait for the notification when compression finishes. Large images can take a while, so let the app run in the background or rely on notifications.

Building from Source

The converter is built from source, so the submodules are required:

git clone --recurse-submodules https://github.com/izzy2lost/CHDBOY
./gradlew assembleRelease

Artifacts appear in app/build/outputs/apk/. A single universal APK is produced, holding arm64-v8a and armeabi-v7a.

Building the native converter needs NDK 30.0.15729638 and CMake 3.30.3, both installable through the SDK manager.

Compatibility

CHDs are written with zstd by default, which chdman learned to read in 0.264. Recent DuckStation, Flycast, PCSX2 and PPSSPP all read it. To target older tooling, flip PORTABLE in Converter.kt to write Deflate instead — larger and slower, but readable by every CHD implementation ever shipped.

Documentation & Policies

• Project Website & Privacy Policy
• GitHub Issues

Attribution

• Originally forked from Pipetto-crypto/Chdman
• The CHD format, and the CD track layout this writer reproduces, are from the MAME project (© MAMEdev)
• libchdr (BSD-3-Clause) provides the reference decoder and the CD-ROM ECC routines
• zstd (BSD / GPLv2) provides the compressor

License

This project is released under the terms of the GNU General Public License v2. See the LICENSE file for full details.

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_{(c) 2025 izzy2lost. Consider supporting future CHDBOY releases on Google Play.}