| LZ4 - Extremely fast compression |
| ================================ |
| |
| LZ4 is lossless compression algorithm, |
| providing compression speed at 400 MB/s per core, |
| scalable with multi-cores CPU. |
| It features an extremely fast decoder, |
| with speed in multiple GB/s per core, |
| typically reaching RAM speed limits on multi-core systems. |
| |
| Speed can be tuned dynamically, selecting an "acceleration" factor |
| which trades compression ratio for more speed up. |
| On the other end, a high compression derivative, LZ4_HC, is also provided, |
| trading CPU time for improved compression ratio. |
| All versions feature the same decompression speed. |
| |
| LZ4 library is provided as open-source software using BSD 2-Clause license. |
| |
| |
| |Branch |Status | |
| |------------|---------| |
| |master | [![Build Status][travisMasterBadge]][travisLink] [![Build status][AppveyorMasterBadge]][AppveyorLink] [![coverity][coverBadge]][coverlink] | |
| |dev | [![Build Status][travisDevBadge]][travisLink] [![Build status][AppveyorDevBadge]][AppveyorLink] | |
| |
| [travisMasterBadge]: https://travis-ci.org/lz4/lz4.svg?branch=master "Continuous Integration test suite" |
| [travisDevBadge]: https://travis-ci.org/lz4/lz4.svg?branch=dev "Continuous Integration test suite" |
| [travisLink]: https://travis-ci.org/lz4/lz4 |
| [AppveyorMasterBadge]: https://ci.appveyor.com/api/projects/status/jc2yhgwyc7qqtsko/branch/master?svg=true "Windows test suite" |
| [AppveyorDevBadge]: https://ci.appveyor.com/api/projects/status/jc2yhgwyc7qqtsko/branch/dev?svg=true "Windows test suite" |
| [AppveyorLink]: https://ci.appveyor.com/project/YannCollet/lz4-1lndh |
| [coverBadge]: https://scan.coverity.com/projects/4735/badge.svg "Static code analysis of Master branch" |
| [coverlink]: https://scan.coverity.com/projects/4735 |
| |
| > **Branch Policy:** |
| |
| > - The "master" branch is considered stable, at all times. |
| > - The "dev" branch is the one where all contributions must be merged |
| before being promoted to master. |
| > + If you plan to propose a patch, please commit into the "dev" branch, |
| or its own feature branch. |
| Direct commit to "master" are not permitted. |
| |
| Benchmarks |
| ------------------------- |
| |
| The benchmark uses [lzbench], from @inikep |
| compiled with GCC v6.2.0 on Linux 64-bits. |
| The reference system uses a Core i7-3930K CPU @ 4.5GHz. |
| Benchmark evaluates the compression of reference [Silesia Corpus] |
| in single-thread mode. |
| |
| [lzbench]: https://github.com/inikep/lzbench |
| [Silesia Corpus]: http://sun.aei.polsl.pl/~sdeor/index.php?page=silesia |
| |
| | Compressor | Ratio | Compression | Decompression | |
| | ---------- | ----- | ----------- | ------------- | |
| | memcpy | 1.000 | 7300 MB/s | 7300 MB/s | |
| |**LZ4 fast 8 (v1.7.3)**| 1.799 |**911 MB/s** | **3360 MB/s** | |
| |**LZ4 default (v1.7.3)**|**2.101**|**625 MB/s** | **3220 MB/s** | |
| | LZO 2.09 | 2.108 | 620 MB/s | 845 MB/s | |
| | QuickLZ 1.5.0 | 2.238 | 510 MB/s | 600 MB/s | |
| | Snappy 1.1.3 | 2.091 | 450 MB/s | 1550 MB/s | |
| | LZF v3.6 | 2.073 | 365 MB/s | 820 MB/s | |
| | [Zstandard] 1.1.1 -1 | 2.876 | 330 MB/s | 930 MB/s | |
| | [Zstandard] 1.1.1 -3 | 3.164 | 200 MB/s | 810 MB/s | |
| | [zlib] deflate 1.2.8 -1| 2.730 | 100 MB/s | 370 MB/s | |
| |**LZ4 HC -9 (v1.7.3)** |**2.720**| 34 MB/s | **3240 MB/s** | |
| | [zlib] deflate 1.2.8 -6| 3.099 | 33 MB/s | 390 MB/s | |
| |
| [zlib]: http://www.zlib.net/ |
| [Zstandard]: http://www.zstd.net/ |
| |
| LZ4 is also compatible and well optimized for x32 mode, for which it provides +10% speed performance. |
| |
| |
| Documentation |
| ------------------------- |
| |
| The raw LZ4 block compression format is detailed within [lz4_Block_format]. |
| |
| To compress an arbitrarily long file or data stream, multiple blocks are required. |
| Organizing these blocks and providing a common header format to handle their content |
| is the purpose of the Frame format, defined into [lz4_Frame_format]. |
| Interoperable versions of LZ4 must respect this frame format. |
| |
| [lz4_Block_format]: doc/lz4_Block_format.md |
| [lz4_Frame_format]: doc/lz4_Frame_format.md |
| |
| |
| Other source versions |
| ------------------------- |
| |
| Beyond the C reference source, |
| many contributors have created versions of lz4 in multiple languages |
| (Java, C#, Python, Perl, Ruby, etc.). |
| A list of known source ports is maintained on the [LZ4 Homepage]. |
| |
| [LZ4 Homepage]: http://www.lz4.org |