RedLZ77 | SuperCollider 3.13.0 Help

Description

See http://michael.dipperstein.com/lzss/ and http://www.binaryessence.com/dct/en000138.htm

A dictionary look-up compressor that performs best with very long repeating patterns e.g. [0, 1, 2, 3, 0, 1, 2, 3, 0, 1, 2, 3, 0, 1, 2, 3, 0, 1, 2, 3, 0, 1, 2, 3]. Use RedLZSS for better albeit slower compression.

NOTE: Works with Integer, Float and Symbol. Can also take a String instead of an Array.

Class Methods

.compress

Returns an array with length, distance and value...

.decompress

Returns an array.

.window

Maximum sliding window size. The default is 4096.

.length

Maximum length for matching pattern. The default is 32.

Examples

a= [0, 1, 2, 3, 0, 1, 2, 3, 0, 1, 2, 3, 0, 1, 2, 3, 0, 1, 2, 3, 0, 1, 2, 3];
b= RedLZ77.compress(a);
b.size/a.size;  //compressed to 58%
c= RedLZ77.decompress(b);
a==c

a= "AABCBBABC";  //string instead of array
b= RedLZ77.compress(a);
c= RedLZ77.decompress(b);
a==c.join;

a= "abracadabra".ascii;
b= RedLZ77.compress(a);
c= RedLZ77.decompress(b);
a==c

a= "JOEYNJOEYNJOEYJOEYNJOEYNJOEYJOEYNJOEYNJOEYJOEYNJOEYNJOEY".ascii;
b= RedLZ77.compress(a);
b.size/a.size;  //compressed to 41%
c= RedLZ77.decompress(b);
a==c

a= "Man is distinguished, not only by his reason, but by this singular passion from other animals, which is a lust of the mind, that by a perseverance of delight in the continued and indefatigable generation of knowledge, exceeds the short vehemence of any carnal pleasure.".ascii;
b= RedLZ77.compress(a);
b.size/a.size;  //expanded to 117%
c= RedLZ77.decompress(b);
c.collect{|x| x.asAscii}.join;
a==c

a= {|i| [0, 0, 0, 0.1].choose}.dup(5000);
RedLZ77.window= 512;  //decrease window and length to speed up compression
RedLZ77.length= 16;
b= RedLZ77.compress(a);  //very slow to compress large arrays
b.size/a.size;  //compressed to around 24% (20% with default window and length values)
c= RedLZ77.decompress(b);  //fast to decompress
c.size
a==c

helpfile source: HelpSource/Classes/RedLZ77.schelp
link::redSys/Classes/RedLZ77::

RedLZ77Extension