zzip

Zzip, a new compression tool still under development, can compress files with a very high compression ratio. Compared to WinZip 7.0, you can gain, at least, 15 %. Zzip has a lot of useful features (like support for file integrity tests, built-in multimedia detection/compression...).

With Zzlib, you can also use Zzip as a library (dll) in one of your program.

Source code of Zzip/Zzlib is released under the GNU LGPL.

Zzip compression algorithm is mainly based on the Burrows-Wheeler Transform method developed by Mike Burrows and David Wheeler. Here are the different steps :

• RLE packing if necessary
• some transformations for text, multimedia and win32 binary files (eol coding, delta-encoding,...)
• Burrows-Wheeler Transformation, it's a suffix sorting (Bentley-Sedgewick ternary sorting with initial bucket sorting)
• MTF like transformation
• arithmetic coding (two groups, ternary sequence & structured model)

  Switch picks:

• -... Block size (e.g. -3m,-3072k) + block size of 1 Mb : -1m + block size of 2347 kb : -2347k
• -a Adaptive block size reduction
• -mx MaXimum compression
• -mm MultiMedia compression

-mx gives the best compression ratio but compression is 15% slower

-a is useful with binary or tar files, it reduces the block size adaptively to give a better compression ratio, but compression is 5% slower

-mm enables a special algorithm for image and wav files, use it only for multimedia files since it can give a worse compression ratio for regular files

The program has following filters (quotes from the source code):

* Some phrase replacements.

* some ASCII transformations: alphabet reordering, carriage-return tagging, upper-case letter tagging

The compressor is featured in the BWT comparison.

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