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Zstd, short for Zstandard, is a new lossless compression algorithm, which provides both good compression ratio and speed for your standard compression needs. "Standard" translates into everyday situations which neither look for highest possible ratio nor extreme speeds.s
It is provided as a BSD-license package, hosted on Github.
| Branch | Status |
|---|---|
| master |  |
| dev |  |
For a taste of its performance, here are a few benchmark numbers, completed on a Core i7-5600U @ 2.6 GHz, using fsbench 0.14.3, an open-source benchmark program by m^2.
| Name | Ratio | C.speed | D.speed |
|---|---|---|---|
| MB/s | MB/s | ||
| zlib 1.2.8 -6 | 3.099 | 21 | 320 |
| zstd | 2.871 | 250 | 650 |
| zlib 1.2.8 -1 | 2.730 | 70 | 300 |
| LZ4 HC r131 | 2.720 | 25 | 2100 |
| QuickLZ 1.5.1b6 | 2.237 | 370 | 415 |
| LZO 2.06 | 2.106 | 400 | 580 |
| Snappy 1.1.0 | 2.091 | 330 | 1100 |
| LZ4 r131 | 2.084 | 450 | 2100 |
| LZF 3.6 | 2.077 | 200 | 560 |
An interesting feature of zstd is that it can qualify as both a reasonably strong compressor and a fast one.
Zstd delivers high decompression speed, at more than >600 MB/s per core. Obviously, your exact mileage will vary depending on your target system.
Zstd compression speed will be configurable to fit different situations. The first version offered is the fast one, at ~250 MB/s per core, which is suitable for a few real-time scenarios. But similar to LZ4, zstd can offer derivatives trading compression time for compression ratio, keeping decompression properties intact. "Offline compression", where compression time is of little importance because the content is only compressed once and decompressed many times, is therefore within scope.
Note that high compression derivatives still have to be developed. It's a complex area which will require time and benefit from contributions.
Another property zstd is developed for is configurable memory requirement, with the objective to fit into low-memory configurations, or servers handling many connections in parallel.
Zstd entropy stage is provided by Huff0 and FSE, of Finite State Entrop library.
Zstd is still considered experimental at this stage. Specifically, it doesn't guarantee yet that its current stream/file format will remain supported in future versions of the library. Therefore, only use Zstd in environments where you can control the availability of the decompression library. "Stable" status, including official documented format format and long-term support commitment, is projected sometimes early 2016.
Branch Policy
The "dev" branch is the one where all contributions will be merged before reaching "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.