Lempel-Ziv-Oberhumer
1108891
210078606
2008-05-04T10:14:07Z
137.204.103.3
{{Importance|date=February 2008}}
{{Citations missing|date=February 2008}}
'''Lempel-Ziv-Oberhumer''' ('''LZO''') is a [[lossless]] [[data compression]] [[algorithm]] that is focused on decompression speed.
A [[free software]] tool which implements it is [[lzop]]. The original library was written in [[ANSI C]], and it has been made available under the [[GNU General Public License]]. Versions of LZO are available for the [[Perl]], [[Python (programming language)|Python]] and [[Java (programming language)|Java]] languages. The [[copyright]] for the code is owned by Markus F. X. J. Oberhumer.
The LZO library implements a number of algorithms with the following features:
* Compression is comparable in speed to [[deflate]] compression.
* Decompression is ''very'' fast, in non-trivial cases able to exceed the speed of a straight memory-to-memory copy due to the reduced memory-reads.
* Requires an additional buffer during compression (of size 8 kB or 64 kB, depending on compression level).
* Requires no additional memory for decompression other than the source and destination buffers.
* Allows the user to adjust the balance between compression quality and compression speed, without affecting the speed of decompression.
LZO supports overlapping compression and in-place decompression.
LZO is a block compression algorithm — it compresses and decompresses a block of data. Block size must be the same for compression and decompression.
LZO compresses a block of data into ''matches'' (a sliding dictionary) and ''runs'' of non-matching literals to produce good results on highly redundant data and deals acceptably with non-compressible data, only expanding uncompressible data by a maximum of 1/64th of the original size when measured over a block size of at least 1kB.
Various LZO implementations are reported to work under [[Win32]], [[IBM AIX (operating system)|AIX]], ConvexOS, [[IRIX]], [[Mac OS]], [[Palm OS]], PS1 ([[Sony PlayStation]]), [[Solaris (operating system)|Solaris]], [[SunOS]], TOS (Atari ST), [[Linux]] and [[VxWorks]].
==External links==
*[http://www.oberhumer.com/opensource/lzo/ www.oberhumer.com LZO source page]
*[http://www.lzop.de/ LZO/LZOP binary downloads]
{{Compression Methods}}
[[Category:Lossless compression algorithms]]
[[Category:Free data compression software]]
[[Category:C libraries]]
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