This is the command bzz that can be run in the OnWorks free hosting provider using one of our multiple free online workstations such as Ubuntu Online, Fedora Online, Windows online emulator or MAC OS online emulator
PROGRAM:
NAME
bzz - DjVu general purpose compression utility.
SYNOPSIS
Encoding:
bzz -e[blocksize] inputfile outputfile
Decoding:
bzz -d inputfile outputfile
DESCRIPTION
The first form of the command line (option -e) compresses the data from file inputfile and
writes the compressed data into outputfile. The second form of the command line (option
-d) decompressed file inputfile and writes the output to outputfile.
OPTIONS
-d Decoding mode.
-e[blocksize]
Encoding mode. The optional argument blocksize specifies the size of the input
file blocks processed by the Burrows-Wheeler transform expressed in kilobytes. The
default block sizes is 2048 KB. The maximal block size is 4096 KB. Specifying a
larger block size usually produces higher compression ratios and increases the
memory requirements of both the encoder and decoder. It is useless to specify a
block size that is larger than the input file.
ALGORITHMS
The Burrows-Wheeler transform is performed using a combination of the Karp-Miller-
Rosenberg and the Bentley-Sedgewick algorithms. This is comparable to (Sadakane, DCC 98)
with a slightly more flexible ranking scheme. Symbols are then ordered according to a
running estimate of their occurrence frequencies. The symbol ranks are then coded using a
simple fixed tree and the ZP binary adaptive coder (Bottou, DCC 98).
The Burrows-Wheeler transform is also used in the well known compressor bzip2. The
originality of bzz is the use of the ZP adaptive coder. The adaptation noise can cost up
to 5 percent in file size, but this penalty is usually offset by the benefits of
adaptation.
PERFORMANCE
The following table shows comparative results (in bits per character) on the Canterbury
Corpus ( http://corpus.canterbury.ac.nz ). The very good bzz performance on the
spreadsheet file excl puts the weighted average ahead of much more sophisticated
compressors such as fsmx.
┌─────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
├─────────────────────────────────────────────────────────────────────────────────────────────────────────────┤
│ fsmx 2.10 0.79 1.89 1.48 2.52 1.84 2.21 2.24 2.29 2.91 2.35 1.63 2.06 │
│ bzz 2.25 0.76 2.13 0.78 2.67 2.00 2.40 2.52 2.60 3.19 2.52 1.44 2.16 │
└─────────────────────────────────────────────────────────────────────────────────────────────────────────────┘
Note that DjVu contributors have several entries in this table. Program compress was
written some time ago by Joe Orost. Program ppmd is an improvement of the PPM-C method
invented by Paul Howard.
CREDITS
Program bzz was written by Léon Bottou <[email protected]> and was then improved
by Andrei Erofeev <[email protected]>, Bill Riemers <[email protected]> and
many others.
Use bzz online using onworks.net services
