PAQ
PAQ is a compression program for compressed archiving of files , which compared to other formats usually has the highest data compression rate, at the expense of very long runtimes and high storage requirements. PAQ is a command line program that is open source , but does not yet have its own GUI . Such is the PAQCompress project on Github , FrontPAQ (development discontinued) or z. B. PeaZip is available on Windows and Linux .
PAQ was originally developed as PAQAR by Matt Mahoney and has been improved by various authors since then.
Properties of the PAQ packer
PAQ-8 uses context mixing which uses single bit predictions from a number of models combined with a neural network and arithmetic coding . Before that, the data is subjected to text preprocessing, using seven library files (included), which can be supplemented by other languages. The treatment of JPEG files is noteworthy , the Huffman coding of which is replaced by a more powerful compression algorithm, whereby JPEG files can be further compressed without loss.
ZPAQ
Up to PAQ9, many different PAQ versions were developed that were incompatible with each other. On March 12, 2009, the ZPAQ Level 1 standard was passed and version 1.00 was published. Future versions should remain compatible with it.
Individual evidence
- ↑ Large Text Compression Benchmark , July 19, 2016
- ↑ Current versions of PAQ break archive compatibility with each compression improvement. ZPAQ is intended to fix that. ; Matt Mahoney: Data Compression Programs , accessed January 4, 2010.