LZO
Encyclopedia
Lempel-Ziv-Oberhumer is a lossless data compression
algorithm
that is focused on decompression speed.
LZO supports overlapping compression and in-place decompression. It 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.
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
and Java
languages. The copyright
for the code is owned by Markus F. X. J. Oberhumer. It was originally published in 1996. Various LZO implementations are reported to work under Win32, AIX, ConvexOS, IRIX
, Mac OS
, Palm OS
, PlayStation
, Nintendo 64
, Wii
, Solaris, SunOS
, TOS
(Atari ST), Linux
and VxWorks
.
Data compression
In computer science and information theory, data compression, source coding or bit-rate reduction is the process of encoding information using fewer bits than the original representation would use....
algorithm
Algorithm
In mathematics and computer science, an algorithm is an effective method expressed as a finite list of well-defined instructions for calculating a function. Algorithms are used for calculation, data processing, and automated reasoning...
that is focused on decompression speed.
Design
The LZO library implements a number of algorithms with the following characteristics:- Compression is comparable in speed to deflateDEFLATEDeflate is a lossless data compression algorithm that uses a combination of the LZ77 algorithm and Huffman coding. It was originally defined by Phil Katz for version 2 of his PKZIP archiving tool and was later specified in RFC 1951....
compression. - Very fast decompression
- 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. It 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.
Implementations
A free softwareFree software
Free software, software libre or libre software is software that can be used, studied, and modified without restriction, and which can be copied and redistributed in modified or unmodified form either without restriction, or with restrictions that only ensure that further recipients can also do...
tool which implements it is lzop
Lzop
lzop is a free software file compression tool which uses LZO and is under the GPL license.Aimed at being very fast, lzop produces files a bit larger than gzip's but with less than a tenth of the CPU use. On many benchmark sites lzop is one of the fastest compressors available...
. The original library was written in ANSI C
ANSI C
ANSI C refers to the family of successive standards published by the American National Standards Institute for the C programming language. Software developers writing in C are encouraged to conform to the standards, as doing so aids portability between compilers.-History and outlook:The first...
, and it has been made available under the GNU General Public License
GNU General Public License
The GNU General Public License is the most widely used free software license, originally written by Richard Stallman for the GNU Project....
. Versions of LZO are available for the Perl
Perl
Perl is a high-level, general-purpose, interpreted, dynamic programming language. Perl was originally developed by Larry Wall in 1987 as a general-purpose Unix scripting language to make report processing easier. Since then, it has undergone many changes and revisions and become widely popular...
, Python
Python (programming language)
Python is a general-purpose, high-level programming language whose design philosophy emphasizes code readability. Python claims to "[combine] remarkable power with very clear syntax", and its standard library is large and comprehensive...
and Java
Java (programming language)
Java is a programming language originally developed by James Gosling at Sun Microsystems and released in 1995 as a core component of Sun Microsystems' Java platform. The language derives much of its syntax from C and C++ but has a simpler object model and fewer low-level facilities...
languages. The copyright
Copyright
Copyright is a legal concept, enacted by most governments, giving the creator of an original work exclusive rights to it, usually for a limited time...
for the code is owned by Markus F. X. J. Oberhumer. It was originally published in 1996. Various LZO implementations are reported to work under Win32, AIX, ConvexOS, IRIX
IRIX
IRIX is a computer operating system developed by Silicon Graphics, Inc. to run natively on their 32- and 64-bit MIPS architecture workstations and servers. It was based on UNIX System V with BSD extensions. IRIX was the first operating system to include the XFS file system.The last major version...
, Mac OS
Mac OS
Mac OS is a series of graphical user interface-based operating systems developed by Apple Inc. for their Macintosh line of computer systems. The Macintosh user experience is credited with popularizing the graphical user interface...
, Palm OS
Palm OS
Palm OS is a mobile operating system initially developed by Palm, Inc., for personal digital assistants in 1996. Palm OS is designed for ease of use with a touchscreen-based graphical user interface. It is provided with a suite of basic applications for personal information management...
, PlayStation
PlayStation
The is a 32-bit fifth-generation video game console first released by Sony Computer Entertainment in Japan on December 3, .The PlayStation was the first of the PlayStation series of consoles and handheld game devices. The PlayStation 2 was the console's successor in 2000...
, Nintendo 64
Nintendo 64
The , often referred to as N64, was Nintendo′s third home video game console for the international market. Named for its 64-bit CPU, it was released in June 1996 in Japan, September 1996 in North America, March 1997 in Europe and Australia, September 1997 in France and December 1997 in Brazil...
, Wii
Wii
The Wii is a home video game console released by Nintendo on November 19, 2006. As a seventh-generation console, the Wii primarily competes with Microsoft's Xbox 360 and Sony's PlayStation 3. Nintendo states that its console targets a broader demographic than that of the two others...
, Solaris, SunOS
SunOS
SunOS is a version of the Unix operating system developed by Sun Microsystems for their workstation and server computer systems. The SunOS name is usually only used to refer to versions 1.0 to 4.1.4 of SunOS...
, TOS
Atari TOS
TOS is the operating system of the Atari ST range of computers. This range includes the 520 and 1040ST, their STF/M/FM and STE variants and the Mega ST/STE. Later, 32-bit machines were developed using a new version of TOS, called MultiTOS, which allowed multitasking...
(Atari ST), Linux
Linux
Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...
and VxWorks
VxWorks
VxWorks is a real-time operating system developed as proprietary software by Wind River Systems of Alameda, California, USA. First released in 1987, VxWorks is designed for use in embedded systems.- History :...
.