3.6 KiB
Zstd, short for Zstandard, is a fast lossless compression algorithm, targeting real-time compression scenarios at zlib-level compression ratio.
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 from a number of compression codecs suitable for real-time. The test was 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 | ||
| zstd 0.3 | 2.858 | 280 | 670 |
| zlib 1.2.8 -1 | 2.730 | 70 | 300 |
| QuickLZ 1.5.1b6 | 2.237 | 370 | 415 |
| LZO 2.06 | 2.106 | 400 | 580 |
| LZ4 r131 | 2.101 | 450 | 2100 |
| Snappy 1.1.0 | 2.091 | 330 | 1100 |
| LZF 3.6 | 2.077 | 200 | 560 |
Zstd can also offer stronger compression ratio at the cost of compression speed, but preserving its decompression speed. In the following test, a few compressors suitable for this scenario are selected (they offer very asymetric performance, useful when compression time has little importance). The test was completed on a Core i7-5600U @ 2.6 GHz, using benchmark 0.6.1, an open-source benchmark program by inikep.
| Name | Ratio | C.speed | D.speed |
|---|---|---|---|
| MB/s | MB/s | ||
| brotli -9 | 3.729 | 4 | 340 |
| zstd 0.3 -9 | 3.447 | 30 | 640 |
| zlib 1.2.8 -9 | 3.133 | 10 | 300 |
| LZO 2.06 -999 | 2.790 | 1 | 560 |
| LZ4 r131 -9 | 2.720 | 25 | 2100 |
Zstd compression speed is highly configurable, by small increment, to fit different situations. Its memory requirement can also be configured to fit into low-memory hardware configurations, or servers handling multiple connections/contexts in parallel.
Zstd entropy stage is provided by Huff0 and FSE, from Finite State Entrop library.
Zstd has not yet reached "stable" status. Specifically, it doesn't guarantee yet that its current compressed format will remain stable and supported in future versions. It may still change to adapt further optimizations still being investigated. That being said, the library is now pretty robust, able to withstand hazards situations, including invalid input. The library reliability has been tested using Fuzz Testing, with both internal tools and external ones. Therefore, it's now safe to test Zstandard even within production environments.
"Stable Format" 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.