Experimental dictionary-based data compressor.
The x3 uses a dictionary and encodes various code-stream events using an arithmetic coding. Details are given here.
The table below gives compression ratios on the Silesia corpus.
| Compressor | lz4 | gzip | xz | zstd | brotli | x3 |
|---|---|---|---|---|---|---|
| dickens | 2.2948 | 2.6461 | 3.6000 | 3.5765 | 3.6044 | 3.7168 |
| mozilla | 2.3176 | 2.6966 | 3.8292 | 3.3769 | 3.6922 | 2.7432 |
| mr | 2.3472 | 2.7138 | 3.6231 | 3.2132 | 3.5317 | 4.0364 |
| nci | 9.1071 | 11.2311 | 23.1519 | 20.7925 | 22.0780 | 19.1103 |
| ooffice | 1.7349 | 1.9907 | 2.5346 | 2.3587 | 2.4818 | 2.0668 |
| osdb | 2.5290 | 2.7138 | 3.5456 | 3.2855 | 3.5812 | 3.6151 |
| reymont | 3.1345 | 3.6396 | 5.0374 | 4.9060 | 4.9747 | 5.1010 |
| samba | 3.5122 | 3.9950 | 5.7778 | 5.5267 | 5.7367 | 4.1871 |
| sao | 1.2639 | 1.3613 | 1.6386 | 1.4479 | 1.5812 | 1.5042 |
| webster | 2.9554 | 3.4372 | 4.9540 | 4.8970 | 4.9188 | 4.9685 |
| xml | 6.9277 | 8.0709 | 12.2910 | 11.8004 | 12.4145 | 9.2249 |
| x-ray | 1.1798 | 1.4035 | 1.8868 | 1.6457 | 1.8096 | 1.9649 |
The following options were used:
lz4 -9gzip --bestxz -9 -ezstd --ultra -22brotli -q 11- The
x3parameters have been optimized for each file individually.
The files come from the Silesia compression corpus.
./x3 [arguments] [input-file] [output-file]
Arguments :
-d: force decompression-z: force compression-f: overwrite existing output file-k: keep (don't delete) input file (default)-t NUM: maximum number of matches (affects compression ratio and speed)-w NUM: window size (in kilobytes, affects compression ratio and speed)
- David Barina, ibarina@fit.vutbr.cz
This project is licensed under the MIT License. See the LICENSE.md file for details.
- David Barina, Experimental lossless data compressor, Microprocessors and Microsystems, Volume 98, 2023, 104803. https://doi.org/10.1016/j.micpro.2023.104803