mirror of
https://github.com/Xevion/easy7zip.git
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f98edef556
- add the "fast compression levels" of zstd via "fast" option (fast=1..64) - change the 7-Zip property sizes of LZ4, LZ5 and Zstandard to 3 - 3 and 5 byte header are valid now (default is 3) - update the Methods-Extern.md file, to reflect the property changes
307 lines
11 KiB
Markdown
307 lines
11 KiB
Markdown
7-Zip external method IDs, that are not included to 7-Zip
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---------------------------------------------------------
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History of this document
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------------------------
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- see https://github.com/mcmilk/7-Zip-zstd/commits/master/DOC/Methods-Extern.md
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Overview of defined ID ranges
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-----------------------------
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ID | Codec, Author | 7-Zip Plugin Author
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---------|------------------------------|----------------------
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F7 0x xx | reserved |
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F7 10 xx | LZHAM, Rich Geldreich | Rich Geldreich
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F7 11 01 | Zstandard, Yann Collet | Tino Reichardt
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F7 11 02 | Brotli, Google | Tino Reichardt
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F7 11 04 | LZ4, Yann Collet | Tino Reichardt
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F7 11 05 | LZ5, Przemyslaw Skibinski | Tino Reichardt
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F7 11 06 | Lizard, Przemyslaw Skibinski | Tino Reichardt
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Range F7 10 xx - LZHAM
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-----------------------
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Description:
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Lossless is a data compression codec with LZMA-like ratios but 1.5x-8x faster
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decompression speed.
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License:
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LZHAM library is provided as open source software using the MIT license.
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7-Zip Container Header:
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``` C
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Byte _ver;
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Byte _dict_size;
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Byte _level;
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Byte _flags;
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Byte _reserved[1];
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```
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Algorithm author: Rich Geldreich
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- Homepage: https://github.com/richgel999/lzham_codec
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- Source: https://github.com/richgel999/lzham_codec
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Codec plugin author: Rich Geldreich
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- Homepage: http://richg42.blogspot.com/2015/11/lzham-custom-codec-plugin-for-7-zip.html
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- Source: https://github.com/richgel999/lzham_codec_devel
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Range F7 11 01, Zstandard
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-------------------------
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Description:
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Zstandard is a real-time compression algorithm, providing high compression
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ratios. It offers a very wide range of compression / speed trade-off, while
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being backed by a very fast decoder.
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License:
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Zstandard library is provided as open source software using the BSD license.
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7-Zip Container Header:
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This header is mandatory and must be exact 3 or 5 bytes. The data within that header
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is for informational purposes only and not used by the decoder. If the header
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is not there, or has another size, the decoder will not decompress the content.
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``` C
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Byte _ver_major; // currently 1
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Byte _ver_minor; // currently 2
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Byte _level; // currently 1..22 or 33..MaxFastLevel
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Byte _reserved[2]; // not given in 3 byte header
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```
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- this header holds some information about the version, which was
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used for creating that 7-Zip container data
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- _ver_major should contain the major release of zstd
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- _ver_minor should contain the major release of zstd
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- _level should contain the level, the data is packed with
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- negative fast level values are stored as fastlevel+32 (33 = fastlevel 1 and so on..)
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- the other two bytes, if present, should be set to zero currently and are reserved for future use
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Algorithm author: Yann Collet
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- Homepage: https://facebook.github.io/zstd/
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- Source: https://github.com/facebook/zstd
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Codec plugin author: Tino Reichardt
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- Homepage: https://mcmilk.de/projects/7-Zip-zstd/
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- Source: https://github.com/mcmilk/7-Zip-zstd
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Modes:
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- threading is supported through skippable frame id 0x184D2A50U
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- all levels are supported (1..22)
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- future versions of zstd will support multithreading out of the box
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- this new format is fully compatible with the one within this codec
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- the codec is used as archiv handler also, see ZstdHandler.cpp
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- this handler is does not use any additional headers, it supports the plain
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zstd v1.0 format
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- when compiled with ZSTD_LEGACY_SUPPORT, then support is increased to these
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addtional version numbers of zstd: v0.1 up v0.7
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- future formats of this algorithm will be fully compatible with release v1.0
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of Zstandard (Zstandard 0.8 == Zstandard 1.0)
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- one ID should be okay for this codec
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Versions:
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The 7-Zip codec will be kept in sync with the current releases of Zstandard.
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Range F7 11 02, Brotli
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----------------------
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Description:
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Brotli is a generic-purpose lossless compression algorithm that compresses
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data using a combination of a modern variant of the LZ77 algorithm, Huffman
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coding and 2nd order context modeling, with a compression ratio comparable to
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the best currently available general-purpose compression methods. It is
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similar in speed with deflate but offers more dense compression.
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License:
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The Brotli library is provided as open source software using the MIT license.
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7-Zip Container Header (3 bytes):
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This header is mandatory and must be exact 3 bytes. The data within that header
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is for informational purposes only and not used by the decoder. If the header
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is not there, or has another size, the decoder will not decompress the content.
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``` C
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Byte _ver_major; // currently 0
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Byte _ver_minor; // currently 6
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Byte _level; // currently 0..11 (Brotli quality)
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```
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- this header holds some information about the version, which was
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used for creating that 7-Zip container data
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- _ver_major should contain the major release of brotli
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- _ver_minor should contain the major release of brotli
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- _level should contain the level, the data is packed with
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Algorithm author: Google Staff
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- Homepage: https://brotli.org/
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- Source: https://github.com/google/brotli
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Codec plugin author: Tino Reichardt
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- Homepage: https://mcmilk.de/projects/7-Zip-zstd/
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- Source: https://github.com/mcmilk/7-Zip-zstd
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Modes:
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- threading is supported through skippable frame id 0x184D2A50U
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- all levels are supported (1..11)
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- one ID should be okay for this codec
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Versions:
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The 7-Zip codec will be kept in sync with the current releases of Brotli.
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Range F7 11 04, LZ4
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-------------------
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Description:
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LZ4 is lossless compression algorithm, providing compression speed at 400 MB/s
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per core (0.16 Bytes/cycle). It features an extremely fast decoder, with speed
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in multiple GB/s per core (0.71 Bytes/cycle). A high compression derivative,
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called LZ4_HC, is available, trading customizable CPU time for compression
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ratio.
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License:
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LZ4 library is provided as open source software using the BSD license.
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7-Zip Container Header:
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This header is mandatory and must be exact 3 or 5 bytes. The data within that header
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is for informational purposes only and not used by the decoder. If the header
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is not there, or has another size, the decoder will not decompress the content.
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``` C
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Byte _ver_major; // currently 1
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Byte _ver_minor; // currently 7
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Byte _level; // 1..12
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Byte _reserved[2]; // not given in 3 byte header
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```
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- this header holds some information about the version, which was
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used for creating that 7-Zip container data
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- _ver_major should contain the major release of LZ4
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- _ver_minor should contain the major release of LZ4
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- _level should contain the level, the data is packed with
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- the other two bytes, if present, should be set to zero currently and are reserved for future use
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Algorithm author: Yann Collet
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- Homepage: https://lz4.github.io/lz4/
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- Source: https://github.com/lz4/lz4
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Codec plugin author: Tino Reichardt
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- Homepage: https://mcmilk.de/projects/7-Zip-zstd/
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- Source: https://github.com/mcmilk/7-Zip-zstd
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Modes:
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- threading is supported through skippable frame id 0x184D2A50U
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- all levels of LZ4 v1.7.4 are supported (1..16)
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- the codec is used as archiv handler also, see Lz4Handler.cpp
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- this handler is does not use any additional headers
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- it supports the plain LZ4 v1.7.4 format (this covers all current lz4
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implemetations)
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- future formats of this algorithm should be fully compatible with current
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release
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- one ID should be okay for this codec
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Versions:
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The 7-Zip codec will be kept in sync with the current releases of LZ4.
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Range F7 11 05, LZ5
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-------------------
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Description:
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LZ5 is a modification of LZ4 which gives a better ratio at cost of slower
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compression and decompression.
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License:
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LZ5 library is provided as open source software using the BSD license.
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7-Zip Container Header:
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This header is mandatory and must be exact 3 or 5 bytes. The data within that header
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is for informational purposes only and not used by the decoder. If the header
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is not there, or has another size, the decoder will not decompress the content.
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``` C
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Byte _ver_major; // currently 1
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Byte _ver_minor; // currently 5
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Byte _level; // 1..15
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Byte _reserved[2]; // not given in 3 byte header
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```
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- this header holds some information about the version, which was used for
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creating that 7-Zip container data
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- _ver_major should contain the major release of LZ5
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- _ver_minor should contain the major release of LZ5
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- _level should contain the level, the data is packed with
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- the other two bytes, if present, should be set to zero currently and are reserved for future use
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Algorithm author: Przemyslaw Skibinski
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- Homepage: https://github.com/inikep/lz5
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- Source: https://github.com/inikep/lz5
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Codec plugin author: Tino Reichardt
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- Homepage: https://mcmilk.de/projects/7-Zip-zstd/
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- Source: https://github.com/mcmilk/7-Zip-zstd
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Modes:
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- threading is supported through skippable frame id 0x184D2A50U
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- all levels of v1.5 are supported, which means: 1..15
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- the codec is used as archiv handler also, see Lz5Handler.cpp
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- this handler is does not use any additional headers, it supports the plain
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lz5 v1.5 format
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- future formats of this algorithm will not follow
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- one ID should be okay for this codec
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Versions:
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The 7-Zip LZ5 codec will be frozen to v1.5 of this codec. No updates are planned.
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Range F7 11 06, Lizard
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----------------------
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Description:
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Lizard is an efficient compressor with very fast decompression. It achieves
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compression ratio that is comparable to zip/zlib and zstd/brotli (at low and
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medium compression levels) at decompression speed of 1000 MB/s and faster.
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License:
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Lizard library is provided as open source software using the BSD license.
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7-Zip Container Header:
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This header is mandatory and must be exact 3 bytes. The data within that header
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is for informational purposes only and not used by the decoder. If the header
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is not there, or has another size, the decoder will not decompress the content.
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``` C
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Byte _ver_major; // currently 1
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Byte _ver_minor; // currently 0
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Byte _level; // 10..49
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```
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- this header holds some information about the version, which was used for
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creating that 7-Zip container data
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- _ver_major should contain the major release of Lizard
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- _ver_minor should contain the major release of Lizard
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- _level should contain the level, the data is packed with
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Algorithm author: Przemyslaw Skibinski
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- Homepage: https://github.com/inikep/lizard
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- Source: https://github.com/inikep/lizard
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Codec plugin author: Tino Reichardt
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- Homepage: https://mcmilk.de/projects/7-Zip-zstd/
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- Source: https://github.com/mcmilk/7-Zip-zstd
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Modes:
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- threading is supported through skippable frame id 0x184D2A50U
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- all compression levels of v1.0 are supported, which means:
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1. Level 10..19
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- fastLZ4, designed to give better decompression speed than LZ4 i.e. over 2000 MB/s
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2. Level 20..29
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- LIZv1, designed to give better ratio than LZ4 keeping 75% decompression speed
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3. Level 30..39
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- fastLZ4 + Huffman, add Huffman coding to fastLZ4
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4. Level 40..49
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- LIZv1 + Huffman, give the best ratio
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- comparable to zlib and low levels of zstd/brotli
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- but also decompression speed of 1000 MB/s
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- the codec is used as archiv handler also, see LizardHandler.cpp
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- this handler is does not use any additional headers, it supports the plain lizarv v1.0 format
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- future formats of this algorithm will not follow
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- one ID should be okay for this codec
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Versions:
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The 7-Zip Lizard codec will be kept in sync with the current releases of Lizard.
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