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Lzip 1.3 / 1.12 RC1, компрессор данных на основе LZMA
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ph34r.gif Lzip 1.3

Lzip — компрессор данных, основанный на алгоритме LZMA, со строгой проверкой точности данных и интерфейсом, идентичным bzip2. Декомпрессия происходит со скоростью, близкой к gzip, а уровень сжатия выше, чем у bzip2.

Новая версия автоматически выбирает наименьший возможный размер словаря для каждого файла, уменьшены расходы памяти на декомпрессию.

Также добавлена поддержка декомпрессии архивов новой версии, компрессия которых будет реализована в следующей версии Lzip.

Lzip is a lossless file compressor based on the LZMA (Lempel-Ziv-Markov chain-Algorithm) algorithm designed by Igor Pavlov. The high compression of LZMA comes from combining two basic, well-proven compression ideas: sliding dictionaries (i.e. LZ77/78), and markov models (i.e. the thing used by every compression algorithm that uses a range encoder or similar order-0 entropy coder as its last stage) with segregation of contexts according to what the bits are used for.

Lzip is not a replacement for gzip or bzip2, but a complement; which one is best to use depends on user's needs. Gzip is the fastest and most widely used. Bzip2 compresses better than gzip but is slower, both compressing and decompressing. Lzip decompresses almost as fast as gzip and compresses better than bzip2, but requires more memory and time during compression. These features make lzip well suited for software distribution and data archival.

The amount of memory required for compression is about 6 times the dictionary size, for decompression is a little more than dictionary size. It is also important to appreciate that the decompression memory requirement is set at compression time by the choice of dictionary size.

Lzip has a user interface similar to the one of gzip or bzip2. It replaces every file given in the command line with a compressed version of itself, with the name "original_name.lz". Each compressed file has the same modification date, permissions, and, when possible, ownership as the corresponding original, so that these properties can be correctly restored at decompression time.

If no file names are specified, lzip compresses (or decompresses) from standard input to standard output. In this case, lzip will decline to write compressed output to a terminal, as this would be entirely incomprehensible and therefore pointless.

Lzip will correctly decompress a file which is the concatenation of two or more compressed files. The result is the concatenation of the corresponding uncompressed files. Integrity testing of concatenated compressed files is also supported.

As a self-check for your protection, lzip stores in the file trailer the 32-bit CRC of the original file and the size of the original file, to make sure that the decompressed version of the file is identical to the original. This guards against corruption of the compressed data, and against undetected bugs in lzip (hopefully very unlikely). The chances of data corruption going undetected are microscopic, less than one chance in 4000 million for each file processed. Be aware, though, that the check occurs upon decompression, so it can only tell you that something is wrong. It can't help you recover the original uncompressed data.

Home_http://www.nongnu.org/lzip/lzip.html
Downloads (~57 Kb)_http://ftp.twaren.net...zip-1.3.tar.gz
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18.03.2011 - 14:41
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Lzip 1.12 RC1

Что нового:
Цитата | Quote
· The option "-F, --recompress", which forces recompression of files whose names already have the ".lz" or ".tlz" suffix, has been added.
· The compression time of the option "-0" has been reduced by 2%.
· Prints only one status line for each multi-member file when only one "-v" is specified.
· Prints up to 6 bytes of trailing garbage when "-vvvv" is specified.
· Does not show the message "and `--stdout' was not specified" for file types that can't be read (directories, etc).
· If "--verbose" is not specified, lziprecover now only shows errors and warnings.

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