Distrance said:
I don't get how the archive, and scrubbing are related, and how can you make 4.6GB file into 400MB archive file.
For some games (such as AC:CF and many others), only a little bit of actual disc space is required for the game files. Some games only use 10% of the total DVD capacity, it ranges basically from 10% to 100%. The unused portion of the disc is filled with garbage. The partition table on the disc tells the Wii where to look on the disc for actual game data. The garbage areas are ignored by the Wii, since the partition table doesn't have any entries for those areas so the Wii knows to stay away.
However due to this garbage being there, when you try to compress the ISO you'll get a marginally smaller file (perhaps 4.1gb instead of 4.3gb). The reason is, all that garbage has to be compressed as well, which is basically wasted space, time, and bandwidth.
That's where Wii Scrubber comes in. Just like the Wii, it reads the partition table to determine where the game area is, and which areas are garbage (unused). Then it overwrites the garbage areas with a uniform value (0xFF). When uncompressed, the file is still 4.3gb because it contains loads of 'filler' data, again this is garbage but now it's a type of garbage that is archive friendly.
So when you compress the ISO file (using WinRAR for example), now all of the FF's can be turned into a single value inside the RAR file that says "there are this many FF's in these positions". So instead of your computer storing all those FF's, now it just stores a copy of how many there are, and where they are. This makes the file
significantly smaller when it's compressed, instead of compressing the original ISO that has garbage data in it.
Then when you decompress the file, all those FF's are returned to their original positions and voila, the file returns to it's original size. The game should still play perfectly, since none of the data touched by Wii Scrubber is ever actually used. Of course there might be some games that run sanity checks on the garbage data for copy protection, I'm not sure.
So in the case of Animal Crossing, when the scrubbed ISO is compressed there is only 450mb or so of actual data (that isn't FF). Some games are more (say 1.8gb to 3.5gb), and believe it or not, some are less (Offroad Extreme is 226mb when scrubbed and compressed).
Most games have the game data files in the root of the ISO partition, however some games use a "Resource.rez" (or similar file like "data.big") to hold all of the data in one central file. This prevents people from extracting/changing the game, at least until the compression algorithm of the rez/big files is reverse engineered. These games are typically large (3.8gb or larger) and do not scrub well.
Just thought I'd toss out some of the info I've learned reading these forums and poking around with Trucha Signer and Wii Scrubber.
] On Guard 
