Last updated: 08FEB2023 (see Changelog for details)

Organizing your ROM library can be confusing and tedious, and so in this guide I will show you how I use CHD, PBP, and RVZ files to optimize my collection.

For this guide I will focus on CD-based games, as they often pose the most issues when it comes to compatibility. (Secret tip: for cartridge-based systems like NES, you can generally just use zip files or leave them uncompressed).

Note that the video guide is made with Windows PCs in mind, but I have included Mac instructions where applicable below.

CHD files

CHD (“Compressed Hunks of Data”) files are compressed data files that can be used on most CD-based systems. They are in a lossless compression format, meaning that they perfectly preserve all game data while reducing file sizes. CHDs were originally developed for MAME to compress CD-based arcade games, but now the are compatible with a variety emulators and CD-based consoles.

CHD files are compatible with most emulators for the following systems:

The most common file type to convert to CHD are BIN/CUE files. If you happen to have only BIN files without their corresponding CUE file, use this tool to easily generate CUE files.

Windows instructions:

The MAME-developed tool for CHD conversion is called CHDman, which works well but requires some knowledge of command line to get working. If you would like to try your hand at it, here is a pretty good guide. Luckily, there is now a program that uses a graphical user interface (GUI) to navigate CHDman, and it is called namDHC. That’s what we are going to use in this guide.

Linux instructions:

Check out this handy tool called the tochd converter.

Mac instructions:

Converting game files to CHD format on a Mac is tricky, but very possible. This code is written for bin/cue files but you could do the same with ISO files (see the bottom of the instructions).

Some notes for Mac users:

PBP files (PS1)

Many PS1 games came in multiple discs, and there is a special tool that will let you convert multi-disc PS1 games into one single PBP file. It will also compress the game files to reduce file size, but bear in mind that this is a lossy compression, meaning that you cannot go back to a different file type after converting to PBP (for example, you can switch back and forth with CHD files). There is also some concern that game data is lost in this conversion process, and so if you want to maintain pristine files this may not be the format for you. But for my own use case I haven’t ever ran into issues with PBP files and I prefer the single-file solution they bring.

One downside for PBP files is that they are not compatible with RetroAchievements (more info here). So if you want to earn achievements for your PS1 games, you will need to stick with CHD files and use m3u playlists for multi-disc games.

Note that this conversion tool is only available on Windows, but it is possible for Mac users to run this application via Wine.

PBP conversion instructions (Windows only):

If you have a multi-disc game that uses multiple BIN files, creating a PBP file can be a challenge since it only will load the first BIN file. To get around this limitation, you can combine the BIN files using an app called CDMage. This tool is only available on Windows, but can be run via Wine on Mac too.

m3u playlist files (multi-disc games)

The PBP method above only works for PS1 games, so if you have other systems with multi-disc games, I recommend trying m3u playlists. This method is also great for Mac users who don’t want to deal with using workarounds like Wine to create PBP files for PSX games.

This will effectively hide your .chd files from the emulator menu, but still allow you to launch your games via the m3u playlist.

RVZ files (GameCube and Wii)

When using the Dolphin emulator for GameCube and Wii emulation, you can take advantage of a special compressed format known as RVZ. Converting to this file is super easy, as it can be done in the Dolphin GUI. Note that in order for this to work you need to use Dolphin 5.0-12188 or later. This can be done on Windows or Mac versions of Dolphin.

Note: While in the video above I mention that you have to convert the files one at a time, I have since learned that you can multi-click on the games within the Dolphin window, and then right-click and select “Convert Selected Files” to batch convert them.

CSO files (PSP)

Typical PSP files will come in ISO format, but they are easy to compress into .cso files. I would expect a ~20% reduction in file size with this method. This process is done using a Windows-based tool called UMDGen, but it may be possible to run this app via Wine on Mac, too.

Note that CSO files are currently not compatible with RetroAchievements, and so if you want to earn achievements (for now) you must use the original .iso format. There are multiple user requests with the RetroAchievements team to add CSO binaries to their code, and so this may be resolved in the future.

WUA files (Wii U)

Another file type that is super handy are .wua files, which are compressed files that will work within the Cemu (Wii U) emulator. These will compress everything together into a single file: the base game, DLC, updates, etc.

To get started, you need to be running Cemu 1.27 or later. You also need to load your games, updates, and DLC into the emulator beforehand.

Changelog

12APR2023– added tochd converter as a Linux option

08FEB2023– added PSP (cso) section by request

07FEB2023– added Wii U (wua) section by request

06FEB2023– published guide– added CDMage instructions for consolidating multiple BIN files into a single BIN file, to aid in PBP conversion process.– added m3u section– added note about RetroAchievements not working with PBP files