1 LZ4 - Extremely fast compression 2 ================================ 3 4 LZ4 is lossless compression algorithm, 5 providing compression speed at 400 MB/s per core, 6 scalable with multi-cores CPU. 7 It features an extremely fast decoder, 8 with speed in multiple GB/s per core, 9 typically reaching RAM speed limits on multi-core systems. 10 11 Speed can be tuned dynamically, selecting an "acceleration" factor 12 which trades compression ratio for more speed up. 13 On the other end, a high compression derivative, LZ4_HC, is also provided, 14 trading CPU time for improved compression ratio. 15 All versions feature the same decompression speed. 16 17 LZ4 library is provided as open-source software using BSD 2-Clause license. 18 19 20 |Branch |Status | 21 |------------|---------| 22 |master | [![Build Status][travisMasterBadge]][travisLink] [![Build status][AppveyorMasterBadge]][AppveyorLink] [![coverity][coverBadge]][coverlink] | 23 |dev | [![Build Status][travisDevBadge]][travisLink] [![Build status][AppveyorDevBadge]][AppveyorLink] | 24 25 [travisMasterBadge]: https://travis-ci.org/lz4/lz4.svg?branch=master "Continuous Integration test suite" 26 [travisDevBadge]: https://travis-ci.org/lz4/lz4.svg?branch=dev "Continuous Integration test suite" 27 [travisLink]: https://travis-ci.org/lz4/lz4 28 [AppveyorMasterBadge]: https://ci.appveyor.com/api/projects/status/jc2yhgwyc7qqtsko/branch/master?svg=true "Windows test suite" 29 [AppveyorDevBadge]: https://ci.appveyor.com/api/projects/status/jc2yhgwyc7qqtsko/branch/dev?svg=true "Windows test suite" 30 [AppveyorLink]: https://ci.appveyor.com/project/YannCollet/lz4-1lndh 31 [coverBadge]: https://scan.coverity.com/projects/4735/badge.svg "Static code analysis of Master branch" 32 [coverlink]: https://scan.coverity.com/projects/4735 33 34 > **Branch Policy:** 35 36 > - The "master" branch is considered stable, at all times. 37 > - The "dev" branch is the one where all contributions must be merged 38 before being promoted to master. 39 > + If you plan to propose a patch, please commit into the "dev" branch, 40 or its own feature branch. 41 Direct commit to "master" are not permitted. 42 43 Benchmarks 44 ------------------------- 45 46 The benchmark uses [lzbench], from @inikep 47 compiled with GCC v6.2.0 on Linux 64-bits. 48 The reference system uses a Core i7-3930K CPU @ 4.5GHz. 49 Benchmark evaluates the compression of reference [Silesia Corpus] 50 in single-thread mode. 51 52 [lzbench]: https://github.com/inikep/lzbench 53 [Silesia Corpus]: http://sun.aei.polsl.pl/~sdeor/index.php?page=silesia 54 55 | Compressor | Ratio | Compression | Decompression | 56 | ---------- | ----- | ----------- | ------------- | 57 | memcpy | 1.000 | 7300 MB/s | 7300 MB/s | 58 |**LZ4 fast 8 (v1.7.3)**| 1.799 |**911 MB/s** | **3360 MB/s** | 59 |**LZ4 default (v1.7.3)**|**2.101**|**625 MB/s** | **3220 MB/s** | 60 | LZO 2.09 | 2.108 | 620 MB/s | 845 MB/s | 61 | QuickLZ 1.5.0 | 2.238 | 510 MB/s | 600 MB/s | 62 | Snappy 1.1.3 | 2.091 | 450 MB/s | 1550 MB/s | 63 | LZF v3.6 | 2.073 | 365 MB/s | 820 MB/s | 64 | [Zstandard] 1.1.1 -1 | 2.876 | 330 MB/s | 930 MB/s | 65 | [Zstandard] 1.1.1 -3 | 3.164 | 200 MB/s | 810 MB/s | 66 | [zlib] deflate 1.2.8 -1| 2.730 | 100 MB/s | 370 MB/s | 67 |**LZ4 HC -9 (v1.7.3)** |**2.720**| 34 MB/s | **3240 MB/s** | 68 | [zlib] deflate 1.2.8 -6| 3.099 | 33 MB/s | 390 MB/s | 69 70 [zlib]: http://www.zlib.net/ 71 [Zstandard]: http://www.zstd.net/ 72 73 LZ4 is also compatible and well optimized for x32 mode, for which it provides +10% speed performance. 74 75 76 Documentation 77 ------------------------- 78 79 The raw LZ4 block compression format is detailed within [lz4_Block_format]. 80 81 To compress an arbitrarily long file or data stream, multiple blocks are required. 82 Organizing these blocks and providing a common header format to handle their content 83 is the purpose of the Frame format, defined into [lz4_Frame_format]. 84 Interoperable versions of LZ4 must respect this frame format. 85 86 [lz4_Block_format]: doc/lz4_Block_format.md 87 [lz4_Frame_format]: doc/lz4_Frame_format.md 88 89 90 Other source versions 91 ------------------------- 92 93 Beyond the C reference source, 94 many contributors have created versions of lz4 in multiple languages 95 (Java, C#, Python, Perl, Ruby, etc.). 96 A list of known source ports is maintained on the [LZ4 Homepage]. 97 98 [LZ4 Homepage]: http://www.lz4.org 99