LZ4 - Extremely fast compression

LZ4 is lossless compression algorithm, providing compression speed at 400 MB/s per core, scalable with multi-cores CPU. It also features an extremely fast decoder, with speed in multiple GB/s per core, typically reaching RAM speed limits on multi-core systems.

A high compression derivative, called LZ4_HC, is also provided. It trades CPU time for compression ratio.

Branch	Status
master
dev
visual

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. Direct commit to "master" are not permitted.
• Feature branches can also exist, for dedicated tests of larger modifications before merge into "dev" branch.

Benchmarks

The benchmark uses the Open-Source Benchmark program by m^2 (v0.14.3) compiled with GCC v4.8.2 on Linux Mint 64-bits v17. The reference system uses a Core i5-4300U @1.9GHz. Benchmark evaluates the compression of reference Silesia Corpus in single-thread mode.

Compressor	Ratio	Compression	Decompression
memcpy	1.000	4200 MB/s	4200 MB/s
LZ4 fast (r129)	1.607	680 MB/s	2220 MB/s
LZ4 (r129)	2.101	385 MB/s	1850 MB/s
LZO 2.06	2.108	350 MB/s	510 MB/s
QuickLZ 1.5.1.b6	2.238	320 MB/s	380 MB/s
Snappy 1.1.0	2.091	250 MB/s	960 MB/s
zlib 1.2.8 -1	2.730	59 MB/s	250 MB/s
LZ4 HC (r129)	2.720	22 MB/s	1830 MB/s
zlib 1.2.8 -6	3.099	18 MB/s	270 MB/s

The raw LZ4 block compression format is detailed within lz4_Block_format.

Compressing an arbitrarily long file or data stream requires multiple blocks. 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 too.