ACE (file format)
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ACE is a file format for lossless data compression and archiving of files in electronic data processing. It stands out compared to the ZIP file format by a higher degree of compression at the same time moderate compression speed.
At Ace a LZ77 dictionary compressor with up to four megabytes, similar to the classic Deflate, used to size of the dictionary in conjunction with Huffman entropy coding. Since version 2 content specific pre-filter for PCM audio files, raster graphics files and executable ( Windows ) Program files can be used in addition.
The developer of the format sells a paid Windows program ( WinAce ), with the open, create, and can be changed archives. For the pure Dekomprimiervorgang the manufacturer offers a free unpacker in versions for DOS, Mac OS and Linux. The unpacking of ACE archives but is also supported by many other programs that can deal with multiple formats.
Since ACE is not a free or publicly documented file format like 7z and no reconstructions have been published, only pre-compiled implementations are available. There is an older free version ( 1.2) of the official Kommandozeilenentpackers " unace " which has been released by WinAce -author Marcel Lemke under the GPL. This, however, can not open a newer ACE archives ( 2.0 and higher). Apart from that, in contrast to other proprietary formats such as RAR not disclosed and the decompression algorithm when ACE format.
The Ace format was developed by Marcel Lemke and later bought by e -merge GmbH the rights to it. It was introduced with WinAce, from the developer versions have been published since 1997 and in July 1999 reached version 1.0. On 7 July 2000 was introduced with version 2 of WinAce a new file format that can be used with the specific content prefilter. In the period from 1999 to 2001, the ACE format with the packer WinAce became increasingly known as the Pack rates often higher than those of RAR were slightly lower. Was used the format, especially for the exchange of files and the proliferation of so-called " releases" of black copies of various commercial products such as movies, software and music via newsgroups, and other platforms. Eventually, however, came in a loss of meaning, as the RAR format has been improved from version 2.90 and achieved since then in most cases higher compression rates.