DEFLATE – Standard algorithm based on 32 kB LZ77 and Huffman coding.
PPMd – Dmitry Shkarin's 2002 PPMdH (PPMII/cPPMII) with small changes: PPMII is an improved version of the 1984 PPM compression algorithm (prediction by partial matching).Bzip2 uses two reversible transformations BWT, then Move to front with Huffman coding for symbol reduction (the actual compression element). Bzip2 – The standard Burrows–Wheeler transform algorithm.LZMA2 – modified version of LZMA providing better multithreading support and less expansion of incompressible data.The LZ stage is followed by entropy coding using a Markov chain-based range coder and binary trees. LZMA – A variation of the LZ77 algorithm, using a sliding dictionary up to 4 GB in length for duplicate string elimination.The following compression methods are currently defined: The format's open architecture allows additional future compression methods to be added to the standard.
#MAC 7Z ENCODING ARCHIVE#
to re-assemble an archive from a set of multi-part component files).
There have been additional third-party attempts at writing more concrete documentation based on the released code.
#MAC 7Z ENCODING CODE#
The specification can be found in plain text format in the 'doc' sub-directory of the source code distribution. The official, informal 7z file format specification is distributed with 7-Zip's source code since 2015. The latest stable version of 7-Zip and LZMA SDK is version 21.06. The LZMA SDK 4.62 was placed in the public domain in December 2008. The 7-Zip program is publicly available under the terms of the GNU Lesser General Public License. The 7z format initially appeared as implemented by the 7-Zip archiver. 7z is a compressed archive file format that supports several different data compression, encryption and pre-processing algorithms.