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

RedLZ77.compress(input)

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

RedLZ77.decompress(input)

Returns an array.

RedLZ77.window

RedLZ77.window = value

Maximum sliding window size. The default is 4096.

RedLZ77.length

RedLZ77.length = value

Maximum length for matching pattern. The default is 32.

Inherited class methods

Instance Methods

Inherited instance methods

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: /home/stefan/.local/share/SuperCollider/downloaded-quarks/redSys/HelpSource/Classes/RedLZ77.schelp
link::Classes/RedLZ77::

RedLZ77 : Object Extension