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When audio files are to be processed, either by further compression or for editing, it is desirable to work from an unchanged original (uncompressed or losslessly compressed). Processing of a lossily compressed file for some purpose usually produces a final result inferior to the creation of the same compressed file from an uncompressed original.
Files compressed by compress are typically given the extension ".Z" (modeled after the earlier pack program which used the extension ".z"). Most tar programs will pipe their data through compress when given the command line option "-Z". (The tar program in its own does not compress; it just stores multiple files within one tape archive.)
7-Zip is a free and open-source file archiver, a utility used to place groups of files within compressed containers known as "archives". It is developed by Igor Pavlov and was first released in 1999. [2] 7-Zip has its own archive format called 7z introduced in 2001, [12] but can read and write several others.
7z is a compressed archive file format that supports several different data compression, encryption and pre-processing algorithms. The 7z format initially appeared as implemented by the 7-Zip archiver.
For example, it may use Bzip2 to compress .txt files, while using Deflate for files with a .exe extention. For .com or .sys files, ALZip uses the ALZ algorithm. The ALZ algorithm is slower but has a high compression ratio. It has a faster compression rate than the Deflate algorithm used in the ZIP format, and is comparable to the LZMA algorithm ...
In fact, if we consider files of length N, if all files were equally probable, then for any lossless compression that reduces the size of some file, the expected length of a compressed file (averaged over all possible files of length N) must necessarily be greater than N. [citation needed] So if we know nothing about the properties of the data ...
The file that is produced by lzip is usually given .lz as its filename extension, and the data is described by the media type application/lzip. The lzip suite of programs was written in C++ and C by Antonio Diaz Diaz and is being distributed as free software under the terms of version 2 or later of the GNU General Public License (GPL).
Archiving various uncompressed files via tar and then compressing yields a compressed archive: a .tar.gz file – this is solid compression. A rough graphical representation: In this example, three files each have a common part with the same information, a unique part with information not in the other files, and an "air" part with low-entropy ...