Mimir

Mimir is an open source, local-first toolkit for retro handheld owners.

It is built to help organise ROM libraries safely on-device or on desktop, with an initial focus on multi-disc cleanup and bulk ROM preparation for frontends used on devices like the AYN Odin and Thor.

RetroPup

I run the RetroPup YouTube channel, where you can subscribe for tips, tricks, and tutorials for retro handhelds.

Current Modules

ROM Organiser

Scans a user-selected ROM folder and detects multi-disc games using common naming patterns.

Current behaviour:

• previews intended changes before applying them
• requires confirmation before file operations
• skips conflicts instead of blocking non-conflicting operations
• applies deterministic frontend-specific output rules

Frontend Presets

Current preset support includes:

• ES-DE
• Other

Current preset behaviour:

• ES-DE groups multi-disc games into a per-game folder and generates an .m3u
• Other keeps discs in the platform folder and generates an .m3u

RomZipper

RomZipper scans ROM subfolders and converts supported ROM formats into .zip archives.

Current supported extensions:

• Nintendo handheld: .gb, .gbc, .gba, .nds
• Nintendo home console: .nes, .fds, .fig, .sfc, .smc, .swc
• Nintendo 64: .n64, .v64, .z64
• Atari: .a26, .a52, .a78, .lnx
• Sega home consoles: .md, .gen, .smd, .32x
• Sega 8-bit / portable: .sms, .gg, .sg, .sc
• NEC / other Japanese systems: .pce, .sgx, .ws, .wsc, .ngp, .ngc
• Computer / miscellaneous: .col, .cv, .d64, .tap, .tzx, .z80, .sna, .rom, .mx1, .mx2

Zip naming behaviour:

• strips the original file extension before creating the archive
• example: Pokemon.gba becomes Pokemon.zip

Converter Tools

Mimir's Converter Tools page provides one scan, review, overwrite, progress, and cancellation flow for each supported converter. Every conversion retains the source image unless the CHD delete-source option is selected.

CHDMan

Supported system and source formats:

• Dreamcast: .gdi, .cue, .iso
• PlayStation 1: .cue, .iso
• PlayStation 2: .iso
• Sega CD: .cue, .iso
• Sega Saturn: .cue, .iso
• PlayStation Portable: .iso

Choose either CD or DVD conversion before scanning. For PSP, use DVD. For PS2, use CD with NetherSX2 and DVD with ARMSX2.

Each scan includes compatible files in the selected folder plus matching system subfolders, case-insensitively: dreamcast/dc, playstation 1/ps1/psx, playstation 2/ps2, sega cd/segacd/mega cd/megacd, sega saturn/saturn, and playstation portable/psp. .bin files are consumed through their .cue sheet and are not independent conversion targets.

Conversion progress reports completed images out of the selected total. Users can stop a scan or conversion immediately, or finish the current conversion and stop before the next one. An optional toggle deletes the successfully converted source image; for .cue and .gdi inputs it also deletes the same-folder track files referenced by that descriptor.

Mimir bundles the Android ARM64 CHDMan executable at android/app/src/main/jniLibs/arm64-v8a/libchdman.so, built from the official MAME source revision ecf0add29f06ba131994dca5b88c3a0edf6c2ad8. The C++ runtime is linked statically so CHDMan can be launched directly from Mimir's native-library directory. Mimir detects a missing executable and stops before changing files.

CHDMan is distributed under GPL-2.0-or-later. The included license is available in the app assets at licenses/MAME-GPL-2.0.txt. Before publishing a release, publish the complete corresponding MAME source for revision ecf0add29f06ba131994dca5b88c3a0edf6c2ad8 (including the build instructions used for this binary) or a valid GPLv2 source offer.

Native converter backends

Mimir bundles the following Android ARM64 command-line backends in android/app/src/main/jniLibs/arm64-v8a/:

• DolphinTool: .iso to .rvz, using RVZ with 128 KiB blocks and Zstandard level 5. Expected binary: libdolphintool.so (GPL-2.0-or-later).
• Azahar: decrypted .3ds / .cci to .zcci, using libazahar.so built from Azahar 2126.0-alpha1 revision e11f3da49346a45c400001ea424de298649618c8 (GPL-2.0-or-later). The reproducible standalone-target patch and build instructions are in docs/azahar-compression-cli.patch and docs/azahar-compression-build.md.

NSZ to NSP

Mimir can decompress Nintendo Switch .nsz packages to .nsp. The converter uses the MIT-licensed NSZ 5.0.0 Python package through the embedded Chaquopy Python runtime, with Android ARM64 builds of zstandard and pycryptodome. Select a folder containing .nsz files directly or in a switch / nintendo switch subfolder, scan it, and choose the packages to convert. Source .nsz files are kept after a successful conversion. NSZ requires a user-provided prod.keys file; use the Import prod.keys action on the NSZ to NSP page. Mimir copies the selected file into app-private storage so it remains available after restarts and does not depend on the original document location.

The converter runs entirely on-device. Mimir does not bundle or download Nintendo keys or game content. Only use it with keys and content you are legally entitled to use.

PS Vita Shortcuts

Mimir includes a built-in searchable PS Vita shortcut database.

Current behaviour:

• search by game title or app ID
• select an output directory on-device
• create shortcuts directly from search results
• choose either .psvita or .dpt shortcut files
• generate .dpt files with a [vita_game_id] section followed by the game ID
• detect existing shortcuts in the currently selected format
• allow mistaken additions to be removed immediately from the same screen

ES-DE Custom Systems

The ES-DE Systems tool downloads the latest Android custom-system definitions from GlazedBelmont/es-de-android-custom-systems, scans the selected ROM root for ES-DE system folders, lets users relocate each detected system with a folder picker, and installs the resulting es_systems.xml and es_find_rules.xml under the selected ES-DE folder's custom_systems directory. Default entries retain %ROMPATH%/<system-folder>; relocated entries use absolute Android storage paths. Restart ES-DE after installation so it reloads the definitions.

ScummVM Launchers

On desktop targets, the ScummVM Launchers tool scans the direct child folders of a selected ScummVM Games directory. It locates a local ScummVM executable in common installation locations, or lets you choose the app file, then runs --path=<game-folder> --detect for each folder. The preview creates <game-name>.scummvm beside each game with the detected game ID as its contents; existing launcher files are skipped safely. Detection is currently desktop-only because Android cannot execute a desktop ScummVM binary.

Design Goals

• local-first
• no cloud sync
• no account system
• safe preview before apply
• deterministic file operations
• frontend compatibility first

Tech Stack

• Flutter and Dart
• Riverpod
• Material 3
• Platform adapters for Android, Windows, macOS, and Linux
• Python 3.13 and Chaquopy (NSZ converter)

Flutter Rebuild

The repository root is now the Flutter application. It targets Android, Windows, macOS, and Linux. Shared ROM scanning and planning logic is pure Dart in packages/mimir_core/; platform-specific filesystem access and converter execution live behind adapters.

Web and iOS are intentionally out of scope because Mimir requires direct local filesystem access and bundled converter executables.

Building the Android target requires a python3.13 executable on PATH so Chaquopy can resolve and package the NSZ dependencies. On Homebrew systems, install it with brew install python@3.13.

Requirements

• Flutter 3.47 or newer
• Dart 3.13 or newer
• Android SDK / Java 17 for Android builds
• Xcode for macOS builds
• Visual Studio with the Desktop C++ workload for Windows builds
• GTK development libraries and CMake for Linux builds

Build

From the repository root:

flutter pub get
flutter analyze
flutter test

Android debug APK

flutter build apk --debug --target-platform android-arm64

Desktop debug builds

flutter build windows --debug
flutter build macos --debug
flutter build linux --debug

Desktop converter bundles are expected under resources/bin/ for the target platform. See resources/README.md and tool/release_check.dart before producing a release.

Project Status

Mimir is now a Flutter application focused on ROM organisation workflows.

Current scope:

• multi-disc normalisation
• frontend preset output generation
• ROM zip conversion
• PS Vita shortcut database and on-device shortcut creation
• Flutter UI with native platform adapters for safe local operations

Planned later work may include:

• more frontend-specific rule validation
• broader file format support
• richer Vita shortcut filtering and metadata options
• UI polish and workflow refinement
• GitHub release workflow
• screenshots and user documentation

Open Source

Mimir is an open source project, and suggestions are welcome. If there are tools or workflows you think would be useful for retro handheld owners, open an issue or suggest them through the project page.

GitHub: https://github.com/ItsRetroPup/Mimir

License

MIT. See LICENSE.