Save disk space for ISOs

ISOs are faithful software recreations of game disks. However, at 700 MB (CD) / 1.4 GB (GC Mini-DVD) / 4.7 GB (single-layered DVD) / 25 GB (Blu-Ray), they can get pretty taxing to disk storage, as newer generations of consoles come.

It wouldn't be so bad if not for the fact that the actually useful game data is often only a fraction of that data size - for instance, the Mario 25th Anniversary Wii disk is a 4.7GB game with only a single SNES rom and nothing else (12 MB of useful data, to be precise). So naturally, one would want to trim the extra fat as much as possible. This is what this improved version of a previous guide aims to help for.

How does one lighten ISO / ROM dumps?

There are many ways. Some alter the dump copy forever. Some are playable on only some specific emulators. And many light dumps are unplayable on real hardware (though a bunch are). All depending on the method and the console. So you might want to consider all of this before.

Audio-CD

Sega-CD, PC-Engine, PlayStation, Sega Saturn... what did these have in common was their reliance on the regular CD format. Game developers stored often orchestrated/Redbook music and occasionally voice acting, using the Audio-CD format. Of course, the CD contained also game data.

But it was terribly inefficient when it comes to disk storage. Even a 700 MB CD containing nothing but Audio-CD data can hold at most around 80 minutes worth of sound data.

That's why devs no longer used it, preferring custom audio formats included in the "game data" part of the disk. By the time the PS1 gen came, the Audio-CD part was just used for messages like "Don't put this in a CD player, dumb user!" and little else (exceptions exist, of course!)

• Full Dump:

BIN/ISO + CUE
BIN/ISO is the full disk data, including Audio-CD sound data and game data
CUE is the datasheet file

• Light Dump:

ISO + MP3/WAV + CUE
ISO is the disk data with only the game data
MP3/WAV is the sound data from the Audio-CD, but these formats take much less disk space
CUE is the datasheet file

• Gain: Several hundreds of MBs to just a few dozen, depending on how much this specific game relies on the Audio-CD sound format
• Tools Used: Load the BIN+CUE using a virtual drive, then use a CD dumping tool
• Can be reverted? Yes, just burn the ISO+MP3/WAV+CUE again using a CD burner tool (ImgBurner) either to a physical disk, or as a ISO+BIN file.
• Playable on Hardware? No, but can be reverted to be
• Playable on Emulators? Yes (use virtual drive if needed). Some aren't compatible with MP3 so convert to WAV with MP32WAV if that's the case. You may need Sega Cue Maker.

Examples:

• Princess Crown (SAT): 574 MB >

Padding

Devs often have their games much, much bigger than they need to be. They put garbage data in the disk. Garbage data isn't game data and just bloats the disk size. It's either a sequence of 00/FF (you know what's inside a file if you open it with a hex editor) or randomized garbage data.

Its purpose can be to fill in some spots in the disk so that specific parts of game data are in specific areas of the disk (like the borders) and hence the drive's reading speed is quick enough in these spots for the game to work properly. It's in the best of your interests not to mess with this data arrangement (referred to as LBA and TOC in the case of GC/Wii/PS2/PSP) or else the game might not even work in some cases (it might in others though).

BUT-- the most common bar none use for this is to screw with pirates and people who download ISOs off online sharing websites, by making the ISO bigger and harder to download. Some go a little step further and make that garbage data not just a sequence of 00/FF to make the ISO much, much harder to compress using regular archive formats like zip/7zip/rar... You might be overjoyed to learn this has become the industry standard nowadays.

Of course, there are also the devs who don't merely use garbage data, but also bloat in-game data. For instance, Tengai Makyou IV PSP has a specific FMV movie duplicated a dozen times, and the Megaman Collection on GC stores its sound data using an uncompressed format bringing the size of that portion alone to 1GB. In many of these cases, there's just not much you can do about it without destructively altering game data, so these cases won't be addressed here.

Let's go back to normal padding then, and how to remove it:

GameCube

Dolphin can't play game dumps off compressed archives.

People used to resort to WiiScrubber (Wii) and GCM Utility (GC) to scrub/trim games to end up with dumps that while they had no immediate size change, their randomized garbage data (like "dummy", "padding" or "znull") was still there but zeroed out making archived dumps using zip/7zip/rar formats have stunning gains (from 1.4GB uncompressed to 26MB zipped for Animal Crossing for example!). Of course the file still needed to be uncompressed to its full size everytime you wanted to play it.

However compressed formats incorporating the "padding zeroing" part were made since then, and Dolphin supports them! (Of course, if you're into modding/rom-hacking games, the previous tools might be of interest to you, but this is a story for another time...)

GCZ (Dolphin native archive format) - GC/Wii

• Gain: Immediate (ISO dump size lowers). Considerable, depending on game.
• Tools Used: Dolphin emulator

You need to add the games in your game list under Dolphin (Configuration/Paths).
Select game in game list (you can hold Shift and select multiple ones).
Right-click and choose "Compress selected ISOs". Choose a directory.
It saves a compressed GCZ copy. You might want to delete the original uncompressed ISO.

• Can be reverted? Yes. You can right-click on the GCZ-compressed (in blue) ISOs in Dolphin and choose "Uncompress selected ISOs". Garbage data is still there but zeroed out, which has no effect since it's randomized anyways.
• Playable on Hardware? No
• Playable on Emulators? Only Dolphin.

WBFS - Wii-only

• Gain: Immediate (ISO dump size lowers). Considerable, depending on game.
• Tools Used: Wii Backup Manager

Under the "Files" section, choose "Add" then choose the ISO file you're converting.
Tool is compatible with ISO, CSO (aka CISO) and WBFS disk dumps. When you're done, select the ISO files you added.
Under "Transfer", use the destination format. So, in our case, WBFS. Choose the directory to save it.
It saves a copy in the WFBS format. You might want to delete the original uncompressed ISO.

• Can be reverted? Yes. You "Add" the WBFS disk dump and "Transfer" it to the "ISO" format. Garbage data is still there but zeroed out, which has no effect since it's randomized anyways.
• Playable on Hardware? Yes!! WBFS dumps are playable on Wii.
• Playable on Emulators? Yes - Dolphin

CSO (aka CISO) - Wii-only

• Gain: Immediate (ISO dump size lowers). Less than WBFS.
• Tools Used: Wii Backup Manager. Same as above, but "Transfer" to "CISO".
• Can be reverted? Yes. You "Add" the CSO disk dump and "Transfer" it to the "ISO" format. Garbage data is still there but zeroed out, which has no effect since it's randomized anyways.
• Playable on Hardware? No
• Playable on Emulators? Yes - Dolphin