Compressed ROMs and Disc Images: ZIP, 7Z, CUE/BIN, CHD, RVZ, and Extraction

LaunchBox records the path to a game file and passes that path to the selected emulator. The emulator, not LaunchBox, decides which ROM and disc-image formats it can run. LaunchBox can also unpack ZIP, 7Z, and RAR archives before launch when an emulator needs the file inside.

Start with these three rules

1. Import the file the emulator expects, usually a descriptor such as CUE or GDI rather than every track it references.

2. Leave a file compressed only if the emulator reads that format directly, or enable LaunchBox extraction for that emulator and platform.

3. Renaming a file extension does not convert the file. Use a format-aware conversion tool and verify the result before removing the source.

ROMs, archives, images, descriptors, and playlists

• ROM: a cartridge or chip dump, commonly identified by a system-specific extension.

• Archive: a container such as ZIP, 7Z, or RAR. It may contain one game file, several related files, or several unrelated games.

• Disc image: stored disc data, such as ISO, BIN, CHD, RVZ, or CSO.

• Descriptor: a small text or metadata file, such as CUE, GDI, CCD, or MDS, that describes one or more companion files.

• M3U: a text playlist that tells a compatible emulator which disc images belong to a multi-disc game. It is unrelated to a LaunchBox library playlist.

ZIP, 7Z, and RAR archives

LaunchBox for Windows recognizes ZIP, 7Z, and RAR as archives for its Extract ROM archives before running option. Recognition by LaunchBox does not mean the emulator can open the archive directly.

• ZIP: widely supported by cartridge emulators and used by MAME for ROM sets. Direct emulator support is often preferable to extraction.

• 7Z: can provide strong compression, but direct emulator support is less universal. Temporary extraction can add significant startup time for large images.

• RAR: can be extracted by LaunchBox's archive handling, but direct support still depends on the emulator.

For an ordinary console library, one launchable game per archive is the safest arrangement. If an archive contains multiple unrelated ROMs, extraction may choose a different file than you intended.

CUE and BIN

A CUE sheet describes the tracks of a disc, commonly stored in one or more BIN files. When the emulator supports CUE/BIN, import and launch the CUE.

• Keep the CUE and every referenced BIN in their original relative arrangement.

• Do not import each BIN track as a separate game.

• Do not rename a BIN without updating the matching FILE line in the CUE.

• Do not assume a multi-track CUE/BIN can be replaced by a plain ISO; audio and track layout may be lost.

A CUE is readable in a text editor. If a game does not launch or has missing music, compare each FILE entry with the exact companion filename.

ISO

ISO normally represents a single data track. It is suitable only when the emulator supports ISO for that system and the original disc layout can be represented correctly. Mixed-mode and multi-track discs often need a descriptor-based format such as CUE/BIN or a compatible CHD instead.

CHD

CHD (Compressed Hunks of Data) is a random-access compressed media format created for MAME and supported by a number of other emulators and RetroArch cores. Depending on the media type and source, it can preserve multi-track optical-disc structure in one file.

• Confirm that the exact emulator or core supports CHD for the platform.

• For console games, import the CHD directly when supported.

• For a multi-disc game, a compatible emulator can use an M3U that lists one CHD per disc.

• For MAME, keep a CHD in the machine's short-name folder beneath a configured ROM path, unless MAME's documentation for that software says otherwise.

LaunchBox does not convert CUE/BIN, ISO, or other images to CHD during import. MAME's chdman can create, extract, inspect, and verify CHDs, but conversion parameters depend on the media type. Keep the source until the converted game, audio, and every disc have been tested.

RVZ, WBFS, and GCZ

These formats are primarily associated with Nintendo GameCube and Wii images used by Dolphin.

• RVZ: Dolphin's recommended compressed format for saving space while retaining disc data needed for verification and emulation.

• WBFS: a common Wii format. Dolphin supports it, but it removes unused disc data and is not the preferred archival choice.

• GCZ: Dolphin's older compressed format.

LaunchBox passes the selected file to Dolphin; it does not perform these conversions. Use Dolphin's Convert File and verification tools when changing formats.

CSO and ZSO

CSO and ZSO are compressed ISO-derived formats used by some emulators, particularly in PSP workflows. Support varies by emulator, version, and emulated system. Import one only when the selected emulator explicitly supports it. CSO2 is not interchangeable with every implementation that accepts ordinary CSO, so verify it against the emulator's current documentation.

GDI and Dreamcast track sets

A GDI file describes a Dreamcast GD-ROM track set. Import the GDI, not each BIN or RAW track. Keep its referenced files and relative paths intact. Some Dreamcast emulators support CHD as an alternative, but conversion should be tested before the source set is removed.

CCD, IMG, and SUB

CloneCD sets commonly use a CCD descriptor with IMG data and, where present, SUB subchannel data. Import the CCD only if the selected emulator supports this set type, and retain all companion files.

MDS and MDF

An MDS descriptor contains layout information for one or more MDF image files. Import the MDS when the emulator supports MDS/MDF, and preserve every referenced MDF file.

M3U playlists for multiple discs

An M3U contains one disc path per line. For compatible emulators and RetroArch cores, it gives the emulator a single entry point and enables its disc-changing controls.

• For BIN/CUE discs, list each disc's CUE, not its individual BIN tracks.

• For CHD discs, list each CHD.

• Relative paths are easiest to keep working when the M3U and discs remain together.

• The M3U contains no game data; deleting or moving a listed disc without updating the M3U breaks the playlist.

LaunchBox can also generate an M3U at launch for a combined multi-disc game when Use M3U Playlists for Multiple Discs is enabled for its emulator/platform association. A hand-written M3U may instead be imported as the game's application path.

Which file should I import?

• Single cartridge game: the ROM itself, or a one-game archive the emulator supports directly.

• CUE plus BIN tracks: CUE.

• GDI plus track files: GDI.

• CCD/IMG/SUB set: CCD, when supported.

• MDS/MDF set: MDS, when supported.

• Single ISO, CHD, RVZ, WBFS, GCZ, CSO, or ZSO: that image, when supported by the emulator.

• Multi-disc set with a prepared M3U: M3U, when supported by the emulator.

• Complete MAME set: use the dedicated MAME full-set importer rather than archive extraction.

How the ROM importer chooses files

When you import a folder, LaunchBox groups files that appear to belong to the same game or track set and consults the applicable extensions recorded for emulators that support the selected platform. If CUE is applicable and a matching CUE is present, LaunchBox prioritizes it over same-group track files. Other candidates follow the platform's recorded extension order.

This selection is a convenience, not proof that the chosen emulator supports or can read every detected file. Carefully inspect the Ready to Import page. Remove accidental track, checksum, text, installer, firmware, or unrelated entries before finishing. If a folder's naming is unusual, select the intended descriptor file directly or correct the game path after import.

Configure extraction in LaunchBox

Go to Tools > Manage > Emulators and edit the emulator:

• On Details, Extract ROM archives before running changes the setting across the emulator's associated platform rows.

• On Associated Platforms, the Extract ROMs column lets you control extraction separately for each platform.

When enabled and the game path ends in ZIP, 7Z, or RAR, LaunchBox extracts the archive beneath LaunchBox\ThirdParty\7-Zip\Temp. It then looks first for a recognized launch target: eboot.bin, default.xbe, CUE, MDS, M3U, GDI, or RPX. If none is found, it passes the first file reported from the archive to the emulator.

After the game exits, LaunchBox attempts to remove the files it extracted. The original archive remains unchanged. Extraction happens again on a later launch, so large archives can noticeably delay startup and use considerable temporary disk space.

When extraction is useful

• The emulator does not open ZIP, 7Z, or RAR directly but accepts the contained ROM.

• The archive has one unambiguous game, or contains one of LaunchBox's recognized descriptors.

• The extracted data is reasonably small.

• The emulator does not need to write persistent data beside the extracted game files.

When extraction is a poor choice

• The emulator already supports the archive.

• The archive contains a large disc image that would be unpacked each launch.

• The game or emulator writes saves, patches, or configuration beside the launched file.

• The archive contains multiple unrelated games or an unrecognized launch descriptor.

• The set relies on named parents, clones, BIOS, device archives, or CHDs, as MAME sets do.

Moving and converting safely

1. Keep a recoverable copy of the complete source set.

2. Verify descriptor references and source integrity.

3. Use the emulator project's recommended conversion tool.

4. Test the result directly in the emulator, including audio and disc changes.

5. Edit the LaunchBox game's application path or re-import intentionally.

6. Only remove the source after the replacement and your backup have been verified.

Common problems

• Every BIN or track became a separate game: keep the descriptor entry and remove only the duplicate LaunchBox records. Do not delete the referenced track files.

• CUE game launches without music: a BIN is missing, renamed, or referenced incorrectly, or the image was converted to a format that lost the track layout.

• Archive extracts but the wrong file launches: use a one-game archive, import a supported descriptor, or permanently extract and select the correct file.

• Launch is slow: disable LaunchBox extraction and use a format the emulator can read directly, or permanently extract the game.

• CHD is rejected: confirm platform support, emulator/core version, CHD integrity and version compatibility, and any required companion ROM or parent CHD.

• Game stopped working after a move: update paths inside CUE, GDI, M3U, or other descriptors, or restore the original relative arrangement.

• MAME reports missing files: check MAME/set version compatibility and required parent, BIOS, device, and CHD dependencies; do not unpack the ROM set through LaunchBox.

• The folder importer selected an unexpected file: correct the application path or import the intended descriptor directly, then verify the emulator's supported extensions.

Beginner recommendation

Use one verified format that the selected emulator supports directly. Import descriptors instead of their individual track files, keep companion files together, leave MAME archives untouched, and enable LaunchBox extraction only for simple ZIP, 7Z, or RAR archives that contain a clear launch target.