[comp.compression] primer on compression methods

ted@nmsu.edu (Ted Dunning) (03/27/91)

since so many seem to have missed it, comp.sources.unix just carried
dan bernstein's collection of compression programs.  while i haven't
looked at the code yet, i have read the description in which dan does
a very creditable job of describing the LZ family of compression
algorithms.  if you want a start in finding out more about data
compression in a practical sense, you could do much worse than
starting with this package.

here is the intro from the posting:


Submitted-by: Dan Bernstein <brnstnd@nyu.edu>
Posting-number: Volume 24, Issue 73
Archive-name: yabbawhap/part01

[ The file PATENT gives a nice summary of the issues.  --r$ ]

yabba applies Y compression to its input; unyabba decompresses the
result. whap applies AP compression to its input; unwhap decompresses
the result. whap and unwhap run at about the same speed as UNIX compress
and uncompress, which use LZW coding; yabba and unyabba are two to three
times slower. AP and Y compression are typically 10-20% more effective
than LZW compression in the same amount of memory. Y coding, unlike LZW
coding and AP coding, is unpatented. It should be possible to use these
programs on any reasonable C platform, though they were originally
designed on a BSD UNIX system.