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List:       freebsd-hackers
Subject:    bzip vs gzip
From:       Julian Assange <proff () suburbia ! net>
Date:       1996-09-26 13:47:44
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[http://www.cs.man.ac.uk/arch/people/j-seward/index.html]

   BZIP compresses the usual 14 files from the Calgary Corpus to an
   average of 2.340 bits per byte, which is within about 5% of the best
   known results, and considerably better than the more widespread
   LZ77/LZ78-based compressors [of which Gzip seems to be amongst the
   best]. Memory consumption is controllable, never exceeding 8,100 k
   for compression, and 5,400 k for decompression, even for very long
   files. You can tell BZIP to use less memory via command-line flags,
   giving minimum uses of 1200 k for compression and 600 k for
   decompression. This makes it usable on 8 meg and even 4 meg machines;
   compression is still better than Gzip. For some kinds of
   highly-redundant files, Bzip has been observed to do strikingly (3
   times) better than Gzip.

   BZIP is an infinite-context statistical compressor, using preliminary
   run-length coding of the input, the Burrows-Wheeler block-sorting
   transformation, Fenwick's structured coding model, run-length coding
   of zeroes in the MTF codes, and a DCC95-style arithmetic coder.

   BZIP is distributed under the GNU General Public License, version 2,
   which means you can copy, use and redistribute it freely. It should
   run on any 32-bit platform with an ANSI C compiler; I myself have
   made successful builds, without modifying the sources, on:
   i386/i486-Linux1.2, i386/i486-Linux2.0, i386/i486-Windows95,
   Sparc-SunOS4, Sparc-Solaris2, SGI-Irix, HP-HPUX and HP-NetBSD. In
   practice BZIP should work without modification on any 32-bit
   GNU-supported target. I have also heard that an earlier version runs
   ok on Alphas; successful builds are also reported for a Mac
   Powerbook, and an Acorn R260 running RISC iX.

   BZIP has been heavily tested: the volume of data compressed in the
   final validation tests exceeds 1700 megabytes in 41000 files, with
   the longest file 425 megabytes long. This version, 0.21, is
   completely compatible with the .bz files created by version 0.15 --
   0.21 differs only in being faster, more portable and offering the
   "-c" flag.

-- 
"Of all tyrannies a tyranny sincerely  exercised for the good of its victims  
 may be the most  oppressive.  It may be better to live under  robber barons  
 than  under  omnipotent  moral busybodies,  The robber baron's  cruelty may  
 sometimes sleep,  his cupidity may at some point be satiated; but those who  
 torment us for own good  will torment us  without end,  for they do so with 
 the approval of their own conscience."    -   C.S. Lewis, _God in the Dock_ 
+---------------------+--------------------+----------------------------------+
|Julian Assange RSO   | PO Box 2031 BARKER | Secret Analytic Guy Union        |
|proff@suburbia.net   | VIC 3122 AUSTRALIA | finger for PGP key hash ID =     |
|proff@gnu.ai.mit.edu | FAX +61-3-98199066 | 0619737CCC143F6DEA73E27378933690 |
+---------------------+--------------------+----------------------------------+

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