PAQ file types
PAQ is a family lossless
file compression algorithms, top ranking in data compression contests
like Hutter Prize and holding several records for maximum compressio
ratio in those competitions.
PAQ algorithm family is based on multiple stategies to reduce
redundancies in data, including neural networks, and aims to reduce
compressed size of the data as near as possible to the quantity of
information enthropy contained in the input - which cannot be further
reduced without loss of information.
LPAQ file types
LPAQ is a related project form same author, Matt Mahoney, and provides
less computing-intensive faster compression, roughly one order of
magnitude, at the cost of inferior compression compated to PAQ, but
still comparable or superior to mainstream compression formats like 7Z,
ARC, RAR, ZIPX at maximum copression settings.
LPAQ is a pure compression format, unlike paq and zpaq, so multiple
files needs to be consolidated in a single TAR container before lpaq
compression, creating a .tar.lpaq archive.
ZPAQ file format
ZPAQ designates the current evolution of PAQ/LPAQ project, providing a
backward compatible standard format supporting incremental archiving
and journaling, and AES256 encryption.
ZPAQ executable is multi threaded, and features a more flexible
compression
mechanism, ranging from speed / compression ratio tradeoff similar to
Deflate for lower compression settings up to better than PAQ for
highest compression settings.
See file compression
benchmark, and maximum
compression benchmark pages to see how ZPAQ compares for
compression ratio and
speed to strongest compressor algorithms, as LZMA/PPMD employed in 7Z, ARC,
RAR and ZIPX formars.
Scopes of PAQ, LPAQ,
ZPAQ file formats
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When is PAQ
compression
recommended
PAQ family is unrivaled in the field of maximum compression, but it is
very computing intensive; those formats are recommended when it is
desired to effectively reach the best possibile copression ratio.
ZPAQ, being also capable of faster and lighter compression, in the
range of Deflate-based formats (ZIP, GZip) is more eclectic and is
suitable to be used as general purpose compressor, especially for
user-level backup tasks due the built in capability of incremental
archiving / incremental backup (add newer and modified files only) and
journaling (maintaing multiple copies of modified files).
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Read more about *PAQ
project: PAQ
family
official domain , ZPAQ project, PAQ page on
Wikipedia
PeaZip supports creation
and
extraction of paq, lpaq, and zpaq files: create, open, browse,
test, and
extract *paq
archives, optionally extract all revision of files contained in the
archive, convert any supported archive to paq and zpaq format and
vice-versa.
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.ZPAQ
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Author
Matt Mahoney, 2009
2^32 max number of files
250 TB bytes max input size
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SPEED 
ZPAQ is extremely flexible in terms of speed.
The algorithm is very computing intensive as compression level
increases, but multithreading support, and several optimizations over
its PAQ predecessor, makes it usable for general purpose at least at
medium compression levels on current generation machines.
At lower compression settings speed / compression tradeoff is quite
similar to Deflate, making it compete with fast archiving formats.
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COMPRESSION
RATIO 
ZPAQ compression algorithm provides state of art compression ratio,
outperforming even high compression formats like 7Z, RAR, and ZIPX at
maximum compression settings
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ADVANCED
OPTIONS 
ZPAQ format natively supports journaling and incremental archiving /
incremental backup, and natively supports AES256 encryption,
Error recovery is currently not supported.
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Synopsis: What is PAQ file compression format and how does it compare
to 7z, arc, rar, zipx. What is PAQ family,
which provides maximum compression ratio, with ZPAQ format implementing
strongest compression algorithm currently available. *PAQ format family
extensions: paq, lpaq, and zpaq file types.
Topics: PAQ file extension
specs, lpaq and zpaq file format
PeaZip > FAQ
> PAQ, LPAQ, ZPAQ file extensions
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