[Setup]: Compression

Valid values:	`zip` `zip/1` through `zip/9` `bzip` `bzip/1` through `bzip/9` `lzma` `lzma/fast` `lzma/normal` `lzma/max` `lzma/ultra` (read warning below before using `ultra`) `none`
Default value:	`lzma`

Description:

This specifies the method of compression to use on the files, and optionally the level of compression. Higher levels compress better but take longer doing so, and may also require more memory while compressing/decompressing.

zip is the method of compression employed by .zip files ("deflate"). It is fast in both compression and decompression, and has very low memory requirements (less than 1 MB for both compression and decompression at level 9), but generally does not compress nearly as well as the other supported methods. zip has one unique property, though: unlike the other methods, it will not expand uncompressible data (e.g., files that are already compressed). If a compression level isn't specified, it defaults to 7.

bzip is the method of compression employed by the bzip2 [external link] compressor. It almost always compresses better than zip but is usually slower in both compression and decompression. Up to 4 MB of memory is required during decompression, and up to 8 MB during compression. If a compression level isn't specified, it defaults to 9.

lzma is the method of compression employed by the 7-Zip LZMA [external link] compressor. It typically compresses significantly better than the zip and bzip methods. However, depending on the compression level used, it can be significantly slower at compressing, and consume a lot more memory. The following table summarizes the approximate memory requirements for each of the supported lzma compression levels. If a compression level isn't specified, it defaults to max.

	Decompression	Compression
`fast`	3 MB	3 MB
`normal`	4 MB	27 MB
`max` (default)	10 MB	84 MB
`ultra`	34 MB	369 MB <-- that's not a typo; be careful!

none specifies that no compression be used.

See also:
SolidCompression