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Solid Compression
In computing, solid compression is a method for data compression of multiple files, wherein all the uncompressed files are concatenated and treated as a single data block. Such an archive is called a solid archive. It is used natively in the 7z and RAR formats, as well as indirectly in tar-based formats such as .tar. gz and .tar. bz2. By contrast, the ZIP format is not solid because it stores separately compressed files (though solid compression can be emulated for small archives by combining the files into an uncompressed archive file and then compressing that archive file inside a second compressed ZIP file). Explanation Compressed file formats often feature both compression (storing the data in a small space) and archiving (storing multiple files and metadata in a single file). One can combine these in two natural ways: * compress the individual files, and then archive into a single file; * archive into a single data block, and then compress. The order matters (these oper ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computing
Computing is any goal-oriented activity requiring, benefiting from, or creating computer, computing machinery. It includes the study and experimentation of algorithmic processes, and the development of both computer hardware, hardware and software. Computing has scientific, engineering, mathematical, technological, and social aspects. Major computing disciplines include computer engineering, computer science, cybersecurity, data science, information systems, information technology, and software engineering. The term ''computing'' is also synonymous with counting and calculation, calculating. In earlier times, it was used in reference to the action performed by Mechanical computer, mechanical computing machines, and before that, to Computer (occupation), human computers. History The history of computing is longer than the history of computing hardware and includes the history of methods intended for pen and paper (or for chalk and slate) with or without the aid of tables. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Data Compression
In information theory, data compression, source coding, or bit-rate reduction is the process of encoding information using fewer bits than the original representation. Any particular compression is either lossy or lossless. Lossless compression reduces bits by identifying and eliminating statistical redundancy. No information is lost in lossless compression. Lossy compression reduces bits by removing unnecessary or less important information. Typically, a device that performs data compression is referred to as an encoder, and one that performs the reversal of the process (decompression) as a decoder. The process of reducing the size of a data file is often referred to as data compression. In the context of data transmission, it is called source coding: encoding is done at the source of the data before it is stored or transmitted. Source coding should not be confused with channel coding, for error detection and correction or line coding, the means for mapping data onto a sig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RAR (file Format)
RAR is a proprietary archive file format that supports data compression, error correction and file spanning. It was developed in 1993 by Russian software engineer Eugene Roshal and the software is licensed by ''win.rar GmbH''. The name ''RAR'' stands for ''Roshal Archive''. File format The filename extensions used by RAR are .rar for the data volume set and .rev for the recovery volume set. Previous versions of RAR split large archives into several smaller files, creating a "multi-volume archive". Numbers were used in the file extensions of the smaller files to keep them in the proper sequence. The first file used the extension .rar, then .r00 for the second, and then .r01, .r02, etc. RAR compression applications and libraries (including GUI based WinRAR application for Windows, console rar utility for different OSes and others) are proprietary software, to which Alexander L. Roshal, the elder brother of Eugene Roshal, holds the copyright. Version 3 of RAR is based o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tar (file Format)
In computing, tar is a shell command for combining multiple computer files into a single archive file. It was originally developed for magnetic tape storage reading and writing data for a sequential I/O device with no file system, and the name is short for the format description "tape archive". When stored in a file system, a file that tar reads and writes is often called a ''tarball''. A tarball contains metadata for the contained files including the name, ownership, timestamps, permissions and directory organization. As a file containing other files with associated metadata, a tarball is useful for software distribution and backup. POSIX abandoned ''tar'' in favor of '' pax'', yet ''tar'' continues to have widespread use. History The command was introduced to Unix in January 1979, replacing the tp program (which in turn replaced "tap"). The file structure was standardized in POSIX.1-1988 and later POSIX.1-2001, and became a format supported by most modern file arc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gzip
gzip is a file format and a software application used for file compression and decompression. The program was created by Jean-loup Gailly and Mark Adler as a free software replacement for the compress program used in early Unix systems, and intended for use by GNU (from which the "g" of gzip is derived). Version 0.1 was first publicly released on 31 October 1992, and version 1.0 followed in February 1993. The decompression of the ''gzip'' format can be implemented as a streaming algorithm, an important feature for Web protocols, data interchange and ETL (in standard pipes) applications. File format gzip is based on the DEFLATE algorithm, which is a combination of LZ77 and Huffman coding. DEFLATE was intended as a replacement for LZW and other patent-encumbered data compression algorithms which, at the time, limited the usability of the compress utility and other popular archivers. "gzip" also refers to the gzip file format (described in the table below). In sho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bzip2
bzip2 is a free and open-source file compression program that uses the Burrows–Wheeler algorithm. It only compresses single files and is not a file archiver. It relies on separate external utilities such as tar for tasks such as handling multiple files, and other tools for encryption, and archive splitting. bzip2 was initially released in 1996 by Julian Seward. It compresses most files more effectively than older LZW and Deflate compression algorithms but is slower. bzip2 is particularly efficient for text data, and decompression is relatively fast. The algorithm uses several layers of compression techniques, such as run-length encoding (RLE), Burrows–Wheeler transform (BWT), move-to-front transform (MTF), and Huffman coding. bzip2 compresses data in blocks between 100 and 900 kB and uses the Burrows–Wheeler transform to convert frequently recurring character sequences into strings of identical letters. The move-to-front transform and Huffman coding are then ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ZIP (file Format)
ZIP is an archive file format that supports lossless compression, lossless data compression. A ZIP file may contain one or more files or directories that may have been compressed. The ZIP file format permits a number of Data compression, compression algorithms, though DEFLATE is the most common. This format was originally created in 1989 and was first implemented in PKWARE, Inc.'s PKZIP utility, as a replacement for the previous ARC (file format), ARC compression format by Thom Henderson. The ZIP format was then quickly supported by many software utilities other than PKZIP. Microsoft has included built-in ZIP support (under the name "compressed folders") in versions of Microsoft Windows since 1998 via the "Plus! 98" addon for Windows 98. Native support was added as of the year 2000 in Windows ME. Apple has included built-in ZIP support in macOS, Mac OS X 10.3 (via BOMArchiveHelper, now Archive Utility) and later. Most :Free software operating systems, free operating s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
File Archiver
In computing, a file archiver is utility software that combines computer file, files into a single archive file or in less common cases, multiple files. A minimally designed archiver might concatenate the content of files along with file file name, name and length. A more advanced archiver stores additional metadata, such as the Timestamping (computing), timestamps, file attributes and access control information. An archiver might lossless data compression, compress input file content to reduce the size of the resulting archive. The process of making an archive file is called ''archiving'' or ''packing''. Reconstructing the original files from an archive is called ''unarchiving'', ''unpacking'' or ''extracting''. Multics In the early days of computing, Multics provided the command a basic archiver without compression that descended from the Compatible Time-Sharing System, CTSS command of the same name. Multics also provided a magnetic tape archiver command, , which was perha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Commutativity
In mathematics, a binary operation is commutative if changing the order of the operands does not change the result. It is a fundamental property of many binary operations, and many mathematical proofs depend on it. Perhaps most familiar as a property of arithmetic, e.g. or , the property can also be used in more advanced settings. The name is needed because there are operations, such as division and subtraction, that do not have it (for example, ); such operations are ''not'' commutative, and so are referred to as noncommutative operations. The idea that simple operations, such as the multiplication and addition of numbers, are commutative was for many centuries implicitly assumed. Thus, this property was not named until the 19th century, when new algebraic structures started to be studied. Definition A binary operation * on a set ''S'' is ''commutative'' if x * y = y * x for all x,y \in S. An operation that is not commutative is said to be ''noncommutative''. One says ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
File Format
A file format is a Computer standard, standard way that information is encoded for storage in a computer file. It specifies how bits are used to encode information in a digital storage medium. File formats may be either proprietary format, proprietary or open format, open. Some file formats are designed for very particular types of data: Portable Network Graphics, PNG files, for example, store Raster graphics, bitmapped Graphics file format, images using lossless data compression. Other file formats, however, are designed for storage of several different types of data: the Ogg format can act as a container format (digital), container for different types of multimedia including any combination of sound, audio and video, with or without text (such as subtitles), and metadata. A text file can contain any stream of characters, including possible control characters, and is encoded in one of various Character encoding, character encoding schemes. Some file formats, such as HTML, sca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
