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documentation: rename Methods.txt to Methods.md

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- so the markdown is nice viewable with browsers
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Tino Reichardt
2017-05-19 21:17:26 +02:00
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DOC/Methods-Extern.txt → DOC/Methods-Extern.md
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@@ -1,197 +1,236 @@
7-Zip external method IDs, that are not included to 7-Zip
---------------------------------------------------------
History of this document
------------------------
- 7-Zip Version 15.01, initial release
Overview of defined ID ranges
-----------------------------
F7 0x xx - reserved
F7 10 xx - LZHAM by Rich Geldreich
F7 11 01 - ZStandard by Yann Collet, Tino Reichardt
F7 11 04 - LZ4 by Yann Collet, Tino Reichardt
F7 11 05 - LZ5 by Przemyslaw Skibinski, Tino Reichardt
Range F7 10 xx - LZHAM
-----------------------
Description:
Lossless data compression codec with LZMA-like ratios but 1.5x-8x faster
decompression speed, C/C++
License:
LZHAM library is provided as open source software using a MIT license.
7-Zip Container Header:
Byte _ver;
Byte _dict_size;
Byte _level;
Byte _flags;
Byte _reserved[1];
Algorithm author: Rich Geldreich
Algorithm Homepage: https://github.com/richgel999/lzham_codec
Source code: https://github.com/richgel999/lzham_codec
Codec plugin author: Rich Geldreich
Codec Homepage: http://richg42.blogspot.com/2015/11/lzham-custom-codec-plugin-for-7-zip.html
Source Code: https://github.com/richgel999/lzham_codec_devel
Range F7 11 01, ZStandard
-------------------------
Description:
Zstandard is a real-time compression algorithm, providing high compression
ratios. It offers a very wide range of compression / speed trade-off, while
being backed by a very fast decoder (see benchmarks below). It also offers a
special mode for small data, called dictionary compression, and can create
dictionaries from any sample set.
License:
Zstandard library is provided as open source software using a BSD license.
7-Zip Container Header:
Byte _ver_major; // currently 1
Byte _ver_minor; // currently 1
Byte _level; // currently 1..22
Byte _reserved[2];
- this header holds some information about the version, which was
used for creating that 7-Zip container data
- _ver_major should contain the major release of zstd
- _ver_minor should contain the major release of zstd
- _level should contain the level, the data is packed with
- the other two bytes should be set to zero currently and are
reserved for future use
Algorithm author: Yann Collet
Algorithm Homepage: https://facebook.github.io/zstd/
Source code: https://github.com/facebook/zstd
Codec plugin author: Tino Reichardt
Codec Homepage: https://mcmilk.de/projects/7-Zip-zstd/
Source Code: https://github.com/mcmilk/7-Zip-zstd
Modes:
- threading is supported through skippable frame id 0x184D2A50U
- all levels are supported (1..22)
- future versions of zstd will support multithreading out of the box
-> this new format is fully compatible with the one within this codec
- the codec is used as archiv handler also, see ZstdHandler.cpp
- this handler is does not use any additional headers, it supports the plain
zstd v1.0 format (this covers all current v1.x implemetations)
- when compiled with ZSTD_LEGACY_SUPPORT, then support is increased to these
addtional version numbers of zstd: v0.1 up v0.7
- future formats of this algorithm will be fully compatible with release v1.0 of
ZStandard (ZStandard 0.8 == ZStandard 1.0)
- one ID should be okay for this codec
Versions:
The 7-Zip codec will be kept in sync with the current releases of ZStandard.
Range F7 11 04, LZ4
-------------------
Description:
LZ4 is lossless compression algorithm, providing compression speed at 400 MB/s
per core (0.16 Bytes/cycle). It features an extremely fast decoder, with speed
in multiple GB/s per core (0.71 Bytes/cycle). A high compression derivative,
called LZ4_HC, is available, trading customizable CPU time for compression
ratio. LZ4 library is provided as open source software using a BSD license.
License:
LZ4 library is provided as open source software using a BSD license.
7-Zip Container Header:
Byte _ver_major; // currently 1
Byte _ver_minor; // currently 7
Byte _level; // 1..16
Byte _reserved[2];
- this header holds some information about the version, which was
used for creating that 7-Zip container data
- _ver_major should contain the major release of LZ4
- _ver_minor should contain the major release of LZ4
- _level should contain the level, the data is packed with
- the other two bytes should be set to zero currently and are
reserved for future use
Algorithm author: Yann Collet
Algorithm Homepage: https://lz4.github.io/lz4/
Source code: https://github.com/lz4/lz4
Codec plugin author: Tino Reichardt
Codec Homepage: https://mcmilk.de/projects/7-Zip-zstd/
Source Code: https://github.com/mcmilk/7-Zip-zstd
Modes:
- threading is supported through skippable frame id 0x184D2A50U
- all levels of LZ4 v1.7.4 are supported (1..16)
- the codec is used as archiv handler also, see Lz4Handler.cpp
- this handler is does not use any additional headers, it supports the plain
lz4 v1.7.4 format (this covers all current lz4 implemetations)
- future formats of this algorithm should be fully compatible with current
release
- one ID should be okay for this codec
Versions:
The 7-Zip codec will be kept in sync with the current releases of LZ4.
Range F7 11 05, LZ5
-------------------
Description:
LZ5 is a modification of LZ4 which gives a better ratio at cost of slower
compression and decompression.
License:
LZ5 library is provided as open source software using a BSD license.
7-Zip Container Header:
Byte _ver_major; // currently 1
Byte _ver_minor; // currently 5
Byte _level; // 1..16
Byte _reserved[2];
- this header holds some information about the version, which was
used for creating that 7-Zip container data
- _ver_major should contain the major release of LZ5
- _ver_minor should contain the major release of LZ5
- _level should contain the level, the data is packed with
- the other two bytes should be set to zero currently and are
reserved for future use
Algorithm author: Przemyslaw Skibinski
Algorithm Homepage: https://github.com/inikep/lz5
Source code: https://github.com/inikep/lz5
Codec plugin author: Tino Reichardt
Codec Homepage: https://mcmilk.de/projects/7-Zip-zstd/
Source Code: https://github.com/mcmilk/7-Zip-zstd
Modes:
- threading is supported through skippable frame id 0x184D2A50U
- all levels of v1.5 are supported (1..16)
- the codec is used as archiv handler also, see Lz5Handler.cpp
- this handler is does not use any additional headers, it supports the plain
lz5 v1.5 format
- future formats of this algorithm may not be compatible with current release,
this codec is very experimental
- one ID should be okay for this codec
Versions:
The 7-Zip codec will be kept in sync with the current releases of LZ5.
The current codec plugin supports version v1.5. Version 2.0 will follow, when it
seems to be stable.
---
End of document
Tino Reichardt, 2016-12-28
7-Zip external method IDs, that are not included to 7-Zip
---------------------------------------------------------
History of this document
------------------------
- see https://github.com/mcmilk/7-Zip-zstd/commits/master/DOC/Methods-Extern.txt
Overview of defined ID ranges
-----------------------------
ID | Codec, Author | 7-Zip Plugin Author
---------+------------------------------+----------------------
F7 0x xx | reserved |
F7 10 xx | LZHAM, Rich Geldreich | Rich Geldreich
F7 11 01 | ZStandard, Yann Collet | Tino Reichardt
F7 11 02 | Brotli, Google | Tino Reichardt
F7 11 04 | LZ4, Yann Collet | Tino Reichardt
F7 11 05 | LZ5, Przemyslaw Skibinski | Tino Reichardt
F7 11 06 | Lizard, Przemyslaw Skibinski | Tino Reichardt
Range F7 10 xx - LZHAM
-----------------------
Description:
Lossless is a data compression codec with LZMA-like ratios but 1.5x-8x faster
decompression speed.
License:
LZHAM library is provided as open source software using the MIT license.
7-Zip Container Header:
Byte _ver;
Byte _dict_size;
Byte _level;
Byte _flags;
Byte _reserved[1];
Algorithm author: Rich Geldreich
- Homepage: https://github.com/richgel999/lzham_codec
- Source: https://github.com/richgel999/lzham_codec
Codec plugin author: Rich Geldreich
- Homepage: http://richg42.blogspot.com/2015/11/lzham-custom-codec-plugin-for-7-zip.html
- Source: https://github.com/richgel999/lzham_codec_devel
Range F7 11 01, ZStandard
-------------------------
Description:
Zstandard is a real-time compression algorithm, providing high compression
ratios. It offers a very wide range of compression / speed trade-off, while
being backed by a very fast decoder.
License:
Zstandard library is provided as open source software using the BSD license.
7-Zip Container Header:
Byte _ver_major; // currently 1
Byte _ver_minor; // currently 1
Byte _level; // currently 1..22
Byte _reserved[2];
- this header holds some information about the version, which was
used for creating that 7-Zip container data
- _ver_major should contain the major release of zstd
- _ver_minor should contain the major release of zstd
- _level should contain the level, the data is packed with
- the other two bytes should be set to zero currently and are
reserved for future use
Algorithm author: Yann Collet
- Homepage: https://facebook.github.io/zstd/
- Source: https://github.com/facebook/zstd
Codec plugin author: Tino Reichardt
- Homepage: https://mcmilk.de/projects/7-Zip-zstd/
- Source: https://github.com/mcmilk/7-Zip-zstd
Modes:
- threading is supported through skippable frame id 0x184D2A50U
- all levels are supported (1..22)
- future versions of zstd will support multithreading out of the box
- this new format is fully compatible with the one within this codec
- the codec is used as archiv handler also, see ZstdHandler.cpp
- this handler is does not use any additional headers, it supports the plain
zstd v1.0 format
- when compiled with ZSTD_LEGACY_SUPPORT, then support is increased to these
addtional version numbers of zstd: v0.1 up v0.7
- future formats of this algorithm will be fully compatible with release v1.0
of ZStandard (ZStandard 0.8 == ZStandard 1.0)
- one ID should be okay for this codec
Versions:
The 7-Zip codec will be kept in sync with the current releases of ZStandard.
Range F7 11 02, Brotli
----------------------
Description:
Brotli is a generic-purpose lossless compression algorithm that compresses
data using a combination of a modern variant of the LZ77 algorithm, Huffman
coding and 2nd order context modeling, with a compression ratio comparable to
the best currently available general-purpose compression methods. It is
similar in speed with deflate but offers more dense compression.
License:
The Brotli library is provided as open source software using the MIT license.
7-Zip Container Header (3 bytes):
Byte _ver_major; // currently 0
Byte _ver_minor; // currently 6
Byte _level; // currently 1..11 (Brotli quality)
- this header holds some information about the version, which was
used for creating that 7-Zip container data
- _ver_major should contain the major release of brotli
- _ver_minor should contain the major release of brotli
- _level should contain the level, the data is packed with
Algorithm author: Google Staff
- Homepage: https://brotli.org/
- Source: https://github.com/google/brotli
Codec plugin author: Tino Reichardt
- Homepage: https://mcmilk.de/projects/7-Zip-zstd/
- Source: https://github.com/mcmilk/7-Zip-zstd
Modes:
- threading is supported through skippable frame id 0x184D2A50U
- all levels are supported (1..11)
- one ID should be okay for this codec
Versions:
The 7-Zip codec will be kept in sync with the current releases of Brotli.
Range F7 11 04, LZ4
-------------------
Description:
LZ4 is lossless compression algorithm, providing compression speed at 400 MB/s
per core (0.16 Bytes/cycle). It features an extremely fast decoder, with speed
in multiple GB/s per core (0.71 Bytes/cycle). A high compression derivative,
called LZ4_HC, is available, trading customizable CPU time for compression
ratio.
License:
LZ4 library is provided as open source software using the BSD license.
7-Zip Container Header:
Byte _ver_major; // currently 1
Byte _ver_minor; // currently 7
Byte _level; // 1..12
Byte _reserved[2];
- this header holds some information about the version, which was
used for creating that 7-Zip container data
- _ver_major should contain the major release of LZ4
- _ver_minor should contain the major release of LZ4
- _level should contain the level, the data is packed with
- the other two bytes should be set to zero currently and are
reserved for future use
Algorithm author: Yann Collet
- Homepage: https://lz4.github.io/lz4/
- Source: https://github.com/lz4/lz4
Codec plugin author: Tino Reichardt
- Homepage: https://mcmilk.de/projects/7-Zip-zstd/
- Source: https://github.com/mcmilk/7-Zip-zstd
Modes:
- threading is supported through skippable frame id 0x184D2A50U
- all levels of LZ4 v1.7.4 are supported (1..16)
- the codec is used as archiv handler also, see Lz4Handler.cpp
- this handler is does not use any additional headers
- it supports the plain LZ4 v1.7.4 format (this covers all current lz4
implemetations)
- future formats of this algorithm should be fully compatible with current
release
- one ID should be okay for this codec
Versions:
The 7-Zip codec will be kept in sync with the current releases of LZ4.
Range F7 11 05, LZ5
-------------------
Description:
LZ5 is a modification of LZ4 which gives a better ratio at cost of slower
compression and decompression.
License:
LZ5 library is provided as open source software using the BSD license.
7-Zip Container Header:
Byte _ver_major; // currently 1
Byte _ver_minor; // currently 5
Byte _level; // 1..15
Byte _reserved[2];
- this header holds some information about the version, which was used for
creating that 7-Zip container data
- _ver_major should contain the major release of LZ5
- _ver_minor should contain the major release of LZ5
- _level should contain the level, the data is packed with
- the other two bytes should be set to zero currently and are reserved for
future use
Algorithm author: Przemyslaw Skibinski
- Homepage: https://github.com/inikep/lz5
- Source: https://github.com/inikep/lz5
Codec plugin author: Tino Reichardt
- Homepage: https://mcmilk.de/projects/7-Zip-zstd/
- Source: https://github.com/mcmilk/7-Zip-zstd
Modes:
- threading is supported through skippable frame id 0x184D2A50U
- all levels of v1.5 are supported, which means: 1..15
- the codec is used as archiv handler also, see Lz5Handler.cpp
- this handler is does not use any additional headers, it supports the plain
lz5 v1.5 format
- future formats of this algorithm will not follow
- one ID should be okay for this codec
Versions:
The 7-Zip codec will be frozen to v1.5 of this codec.
---
End of document
Tino Reichardt, 2017-05-19

2
DOC/Methods.txt
View File

@@ -128,8 +128,10 @@ List of defined IDs
11 xx - reserved (Tino Reichardt)
01 - ZSTD
02 - Brotli
04 - LZ4
05 - LZ5
06 - Lizard
06.. - Crypto