About 7-Zip Format

Description

For further information, please visit http://www.7-zip.org

7z is an archive format, providing high compression ratio, by Igor Pavlov. Main features of the 7z format:

  • Open architecture

  • High compression ratio

  • Strong AES-256 encryption

  • Ability to use any compression, conversion or encryption method

  • Supporting files with sizes up to 16000000000 GB

  • Unicode file names

  • Solid compressing

  • Archive headers compressing

7z has open architecture, so it can support any new compression methods.

The following methods are integrated into 7z:

MethodDescription
LZMAImproved and optimized version of LZ77 algorithm
LZMA2LZMA-based compression method. It provides better multithreading support than LZMA.
PPMDDmitry Shkarin’s PPMdH with small changes
BCJConverter for 32-bit x86 executables
BCJ2Converter for 32-bit x86 executables
BZip2Standard BWT algorithm
DeflateStandard LZ77-based algorithm

LZMA is the default and general compression method of 7z format. Main features of LZMA method:

  • High compression ratio

  • Variable dictionary size (up to 4 GB)

  • Compressing speed: about 1 MB/s on 2 GHz CPU

  • Decompressing speed: about 10-20 MB/s on 2 GHz CPU

  • Small memory requirements for decompressing (depend from dictionary size)

  • Small code size for decompressing: about 5 KB

  • Supporting multi-threading and P4’s hyper-threading

LZMA compression algorithm is very suitable for embedded applications. If you want to use LZMA code, you can ask for consultations, custom code programming, and required developer licenses at 7-zip.org.

External links for developers:

Technical Notes

7-Zip compression system of Paquet Builder is based on 7-Zip and LZMA SDK 16.02.

7-Zip Self-Extractors made with Paquet Builder do not support BZip2 nor Deflate methods because LZMA2, LZMA, BCJ/BCJ2 and PPMD are enough to achieve good compression ratios.

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