(See Compression Formats and Standards for formats and Compression Software Implementations for codecs) In computer science and information theory, data compression or source coding is the process of encoding information using fewer bits (or other information-bearing units) than an unencoded representation would use through use of specific encoding schemes. ... Lossless data compression is a class of data compression algorithms that allows the exact original data to be reconstructed from the compressed data. ... A bundle of optical fiber. ... Claude Shannon In information theory, the Shannon entropy or information entropy is a measure of the uncertainty associated with a random variable. ... In computer science, the Kolmogorov complexity (also known as descriptive complexity, Kolmogorov-Chaitin complexity, stochastic complexity, algorithmic entropy, or program-size complexity) of an object such as a piece of text is a measure of the computational resources needed to specify the object. ... Redundancy in information theory is the number of bits used to transmit a message minus the number of bits of actual information in the message. ... In information theory an entropy encoding is a data compression scheme that assigns codes to symbols so as to match code lengths with the probabilities of the symbols. ... In computer science and information theory, Huffman coding is an entropy encoding algorithm used for lossless data compression. ... Adaptive Huffman coding is an adaptive coding technique based on Huffman coding, building the code as the symbols are being transmitted, having no initial knowledge of source distribution, that allows one-pass encoding and adaptation to changing conditions in data. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ... In the field of data compression, Shannon-Fano coding is a technique for constructing a prefix code based on a set of symbols and their probabilities (estimated or measured). ... Range encoding is a form of arithmetic coding, a data compression method, that is believed to be free from arithmetic coding related patents. ... Golomb coding is a form of entropy encoding invented by Solomon W. Golomb that is optimal for alphabets following geometric distributions, that is, when small values are vastly more common than large values. ... An Exponential-Golomb code (or just Exp-Golomb code) of order is a type of universal code, parameterized by a whole number . ... In data compression, a universal code for integers is a prefix-free code that maps the positive integers onto self-delimiting binary codewords, with the additional property that whatever the true probability distribution on integers, the lengths of the codewords are within a constant factor of the lengths that the... Elias gamma code is a universal code encoding the positive integers. ... The Fibonacci code is a universal code which encodes positive integers into binary code words. ... A dictionary coder, also sometimes known as a substitution coder, is any of a number of data compression algorithms which operate by searching for matches between the text to be compressed and a set of strings contained in a data structure (called the dictionary) maintained by the encoder. ... LZ77 and LZ78 are the names for the two lossless data compression algorithms published in papers by Abraham Lempel and Jacob Ziv in 1977 and 1978. ... LZW (Lempel-Ziv-Welch) is a lossless data compression algorithm. ... Lempel-Ziv-Oberhumer (LZO) is a data compression algorithm that is focused on decompression speed. ... DEFLATE is a lossless data compression algorithm that uses a combination of the LZ77 algorithm and Huffman coding. ... Lempel-Ziv-Markov chain-Algorithm (LZMA) is a data compression algorithm in development since 1998 and used in the 7z format of the 7-Zip archiver. ... LZX is the name of an LZ77 family compression algorithm. ... Run-length encoding (RLE) is a very simple form of data compression in which runs of data (that is, sequences in which the same data value occurs in many consecutive data elements) are stored as a single data value and count, rather than as the original run. ... The Burrows-Wheeler transform (BWT, also called block-sorting compression), is an algorithm used in data compression techniques such as bzip2. ... PPM is an adaptive statistical data compression technique based on context modeling and prediction. ... Dynamic Markov Compression (DMC) is a lossless data compression algorithm developed by Gordon Cormack and Nigel Horspool [1]. It uses predictive arithmetic coding similar to prediction by partial matching (PPM), except that the input is predicted one bit at a time (rather than one byte at a time). ... Audio compression is a form of data compression designed to reduce the size of audio files. ... Acoustics is a branch of physics and is the study of sound (mechanical waves in gases, liquids, and solids). ... In mathematics and, in particular, functional analysis, convolution is a mathematical operator which takes two functions f and g and produces a third function that in a sense represents the amount of overlap between f and a reversed and translated version of g. ... In signal processing, sampling is the reduction of a continuous signal to a discrete signal. ... The Nyquist–Shannon sampling theorem is a fundamental result in the field of information theory, in particular telecommunications and signal processing. ... An audio codec is a computer program that compresses/decompresses digital audio data according to a given audio file format or streaming audio format. ... It has been suggested that this article or section be merged with Code Excited Linear Prediction. ... Log Area Ratios (LAR) can be used to represent Reflection Coefficients (another from for Linear Prediction Coefficients) for transmission over a channel. ... Line Spectral Pairs (LSP) are used to represent Linear Prediction Coefficients (LPC) for transmission over a channel. ... Warped Linear Predictive Coding (Warped LPC or WLPC) is a variant of Linear predictive coding in which the spectral representation of the system is modified, for example by replacing the unit delays used in an LPC implementation with first-order allpass filters. ... CELP stands for Code Excited Linear Prediction and is a speech coding algorithm originally proposed by M.R. Schroeder and B.S. Atal in 1984. ... Algebraic Code Excited Linear Prediction or ACELP is a speech encoding algorithm where a limited set of pulses is distributed as excitation to linear prediction filter. ... Graph of μ-law & A-law algorithms An a-law algorithm is a standard companding algorithm, used in European digital communications systems to optimize, modify, the dynamic range of an analog signal for digitizing. ... In telecommunication, a mu-law algorithm (μ-law) is a standard analog signal compression or companding algorithm, used in digital communications systems of the North American and Japanese digital hierarchies, to optimize (in other words, modify) the dynamic range of an audio analog signal prior to digitizing. ... modified discrete cosine transform (MDCT) is a Fourier-related transform based on the type-IV discrete cosine transform (DCT-IV), with the additional property of being lapped: it is designed to be performed on consecutive blocks of a larger dataset, where subsequent blocks are overlapped so that the last half... In mathematics, the Fourier transform is a certain linear operator that maps functions to other functions. ... Psychoacoustics is the study of subjective human perception of sounds. ... Audio level compression, also called dynamic range compression, volume compression, compression, limiting, or DRC (often seen in DVD player settings) is a process that manipulates the dynamic range of an audio signal. ... Speech coding is the compression of speech (into a code) for transmission with speech codecs that use audio signal processing and speech processing techniques. ... Sub-band coding is any form of transform coding that breaks a signal into a number of different frequency bands and encodes each one independently. ... A comparison of different color spaces. ... This example shows an image with a portion greatly enlarged, in which the individual pixels are rendered as little squares and can easily be seen. ... In digital image processing, chroma subsampling is the use of lower resolution for the colour (chroma) information in an image than for the brightness (intensity or luma) information. ... A compression artifact (or artefact) is the result of an aggressive data compression scheme applied to an image, audio, or video that discards some data which is determined by an algorithm to be of lesser importance to the overall content but which is nonetheless discernible and objectionable to the user. ... Run-length encoding (RLE) is a very simple form of data compression in which runs of data (that is, sequences in which the same data value occurs in many consecutive data elements) are stored as a single data value and count, rather than as the original run. ... Fractal compression is a lossy compression method used to compress images using fractals. ... Wavelet compression is a form of data compression well suited for image compression (sometimes also video compression and audio compression). ... Set Partitioning in Hierarchical Trees (SPIHT) is an image compression algorithm that exploits the inherent similarities across subbands in a wavelet decomposition of an image. ... 2-D DCT compared to the DFT The discrete cosine transform (DCT) is a Fourier-related transform similar to the discrete Fourier transform (DFT), but using only real numbers. ... In statistics, principal components analysis (PCA) is a technique that can be used to simplify a dataset; more formally it is a linear transformation that chooses a new coordinate system for the data set such that the greatest variance by any projection of the data set comes to lie on... In telecommunications and computing, bit rate (sometimes written bitrate) is the frequency at which bits are passing a given (physical or metaphorical) point. It is quantified using the bit per second (bit/s) unit. ... In order to intuitively test the effects of an image-processing algorithm on a natural picture a number of test images are in common use in the image-processing field. ... The phrase peak signal-to-noise ratio, often abbreviated PSNR, is an engineering term for the ratio between the maximum possible power of a signal and the power of corrupting noise that affects the fidelity of its representation. ... Quantization, involved in image processing. ... Video compression refers to making a digital video signal use less data, without noticeably reducing the quality of the picture. ... This article does not cite any references or sources. ... It has been suggested that video frame be merged into this article or section. ... The three major picture types found in typical video compression designs are I(ntra) pictures, P(redicted) pictures, and B(i-predictive) pictures (or B(i-directional) pictures). ... Video quality is a characteristic of video passed through a video processing system. ... A video codec is a device or software module that enables video compression or decompression for digital video. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ... 2-D DCT compared to the DFT The discrete cosine transform (DCT) is a Fourier-related transform similar to the discrete Fourier transform (DFT), but using only real numbers. ... Quantized signal Digital signal In digital signal processing, quantization is the process of approximating a continuous range of values (or a very large set of possible discrete values) by a relatively-small set of discrete symbols or integer values. ... A video codec is a device or software module that enables video compression or decompression for digital video. ... Rate distortion theory is the branch of information theory addressing the problem of determining the minimal amount of entropy (or information) R that should be communicated over a channel such that the source (input signal) can be reconstructed at the receiver (output signal) with given distortion D. As such, rate... Constant bit rate (CBR) is a term used in telecommunications, relating to the quality of service. ... Average bit rate refers to the average amount of data transferred per second. ... Variable bit rate (VBR) is a term used in telecommunications and computing that relates to sound or video quality. ... A timeline of events related to information theory, data compression, error correcting codes and related subjects. ...

(See Compression Methods for methods and Compression Software Implementations for codecs) ... In computer science and information theory, data compression or source coding is the process of encoding information using fewer bits (or other information-bearing units) than an unencoded representation would use through use of specific encoding schemes. ... Video compression refers to making a digital video signal use less data, without noticeably reducing the quality of the picture. ... This article does not cite any references or sources. ... The International Electrotechnical Commission (IEC) is an international standards organization dealing with electrical, electronic and related technologies. ... Motion JPEG (M-JPEG) is an informal name for multimedia formats where each video frame or interlaced field of a digital video sequence is separately compressed as a JPEG image. ... MPEG-1 defines a group of Audio and Video (AV) coding and compression standards agreed upon by MPEG (Moving Picture Experts Group). ... MPEG-2 is a standard for the generic coding of moving pictures and associated audio information [1]. It is widely used around the world to specify the format of the digital television signals that are broadcast by terrestrial (over-the-air), cable, and direct broadcast satellite TV systems. ... MPEG-4 Part 2 is a video compression technology developed by MPEG. It belongs to the MPEG-4 ISO/IEC standard (ISO/IEC 14496-2). ... H.264 is a standard for video compression. ... The ITU Telecommunication Standardization Sector (ITU-T) coordinates standards for telecommunications on behalf of the International Telecommunication Union (ITU) and is based in Geneva, Switzerland. ... H.261 is an 1990 ITU video coding standard originally designed for transmission over ISDN lines on which data rates are multiples of 64 kbit/s. ... H.262 is an ITU-T digital video coding standard. ... H.263 is a video codec designed by the ITU-T as a low-bitrate encoding solution for videoconferencing. ... H.264 is a standard for video compression. ... The Peoples Republic of China government is supporting an effort to develop own standard for compressing digital audio and video, to assert its technological independence from the rest of the world. ... Bink is a video file format (extension . ... Dirac is a prototype algorithm for the encoding and decoding (see codec) of raw video. ... Indeo Video (commonly known now simply as Indeo) is a video codec developed by Intel in 1992. ... Motion JPEG (M-JPEG) is an informal name for multimedia formats where each video frame or interlaced field of a digital video sequence is separately compressed as a JPEG image. ... RealVideo is a proprietary video format developed by RealNetworks. ... Theora is a video codec being developed by the Xiph. ... VC-1 is the informal name of the SMPTE 421M video codec standard initially developed by Microsoft. ... TrueMotion VP6 is a video codec developed by On2 Technologies as a successor to earlier efforts such as VP3 and VP5. ... TrueMotion VP7 is a video codec developed by On2 Technologies as a successor to earlier efforts such as VP3, VP5 and TrueMotion VP6. ... Windows Media Video (WMV) is a generic name for the set of video codec technologies developed by Microsoft. ... Audio compression is a form of data compression designed to reduce the size of audio files. ... This article does not cite any references or sources. ... The International Electrotechnical Commission (IEC) is an international standards organization dealing with electrical, electronic and related technologies. ... MPEG-1 Audio Layer 3, more commonly referred to as MP3, is an audio encoding format. ... MPEG-1 Audio Layer II (MP2, sometimes Musicam) is an audio codec defined by ISO/IEC 11172-3. ... MPEG-1 Audio Layer I, commonly abbreviated to MP1, is one of three audio codecs included in the MPEG-1 standard. ... Advanced Audio Coding (AAC) is a standardized, lossy compression and encoding scheme for digital audio. ... High Efficiency AAC (HE-AAC) is a lossy data compression scheme for digital audio. ... High Efficiency AAC (HE-AAC) is a lossy data compression scheme for digital audio. ... High Efficiency AAC (HE-AAC) is a lossy data compression scheme for digital audio. ... The ITU Telecommunication Standardization Sector (ITU-T) coordinates standards for telecommunications on behalf of the International Telecommunication Union (ITU) and is based in Geneva, Switzerland. ... G.711 is an ITU-T standard for audio companding. ... G.722 is a ITU-T standard wideband speech codec operating at 32-64 kbit/s. ... G.722. ... Adaptive Multi Rate - WideBand or AMR-WB is a speech coding standard developed after the AMR using same technology like ACELP. The codec provides excellent speech quality due to wider speech bandwidth of 50 - 7000 Hz compared to narrowband speech codecs which in general are optimized for POTS wireline quality... This article is in need of attention from an expert on the subject. ... G.723. ... G.726 is ITU-T speech codec operating at bit rates of 16-40 kbit/s. ... G.728 is a ITU-T standard for speech coding operating at 16 kbit/s. ... G.729 is an audio data compression algorithm for voice that compresses voice audio in chunks of 10 milliseconds. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ... G.729 is an audio data compression algorithm for voice that compresses voice audio in chunks of 10 milliseconds. ... Dolby Digital is the marketing name for a series of lossy audio compression technologies by Dolby Laboratories. ... Apple Lossless (also known as Apple Lossless Encoder, ALE, or Apple Lossless Audio Codec, ALAC) is an audio codec developed by Apple Inc. ... Adaptive Transform Acoustic Coding (ATRAC) is a family of proprietary audio compression algorithms developed by Sony. ... Free Lossless Audio Codec (FLAC) is a popular file format for audio data compression. ... internet Low Bit Rate Codec (iLBC) is a royalty free narrowband speech codec, developed by Global IP Sound (GIPS). ... Monkey’s Audio is a lossless audio compression codec. ... In telecommunication, a mu-law algorithm (μ-law) is a standard analog signal compression or companding algorithm, used in digital communications systems of the North American and Japanese digital hierarchies, to optimize (in other words, modify) the dynamic range of an audio analog signal prior to digitizing. ... Musepack or MPC is an open source lossy audio codec, specifically optimized for transparent compression of stereo audio at bitrates of 160-180 kbit/s. ... This is a single-channel (mono) format optimized for low-bitrate transmission of speech. ... RealAudio is a proprietary audio format developed by RealNetworks. ... SHN (Shorten) is a file format used to losslessly compress CD-quality audio files (44. ... Speex is a free software speech codec that claims to be unencumbered by patent restrictions. ... Vorbis is an open source, lossy audio codec project headed by the Xiph. ... WavPack is a free, open source lossless audio compression format developed by David Bryant. ... Windows Media Audio (WMA) is brand name for several technically distinct proprietary compressed audio file formats developed by Microsoft. ... TAK (Toms lossless Audio Kompressor) is a lossless audio compressor which promises compression performance similar to Monkeys Audio High and decompression speed similar to FLAC. The codec also supports streaming (necessary headers for decompressing the audio are written to the stream every 2 seconds), error tolerance (single bit... This article does not cite any references or sources. ... The International Electrotechnical Commission (IEC) is an international standards organization dealing with electrical, electronic and related technologies. ... The ITU Telecommunication Standardization Sector (ITU-T) coordinates standards for telecommunications on behalf of the International Telecommunication Union (ITU) and is based in Geneva, Switzerland. ... In computing, JPEG (pronounced JAY-peg; IPA: ) is a commonly used standard method of compression for photographic images. ... JPEG 2000 is a wavelet-based image compression standard. ... The Joint Photographic Experts Group, in addition to their well-known lossy image compression techniques, JPEG and JPEG 2000, also have three standards for lossless compression (of which JPEG-LS has a lossy mode): Lossless JPEG was developed as a late addition to JPEG in 1993, using a completely different... JBIG is a lossless image compression standard from the Joint Bi-level Image Experts Group, standardized as ISO/IEC standard 11544 and as ITU-T recommendation T.82. ... JBIG2 is an image compression standard for bi-level images, developed by the Joint Bi-level Image Experts Group. ... PNG (Portable Network Graphics) is a bitmapped image format that employs lossless data compression. ... Wireless Application Protocol Bitmap Format (shortened to Wireless Bitmap and with file extension . ... The APNG (Animated Portable Network Graphics) file format is an extension to the Portable Network Graphics (PNG) specification proposed by Stuart Parmenter and Vladimir Vukicevic of the Mozilla Corporation. ... ICER is a wavelet-based image compression file format used by the NASA Mars Rovers. ... Multiple-image Network Graphics (MNG) (IPA pronunciation: ) is a public graphics file format for animated images. ... .BMP or . ... An example of a GIF image. ... ILBM is a subtype of the Interchange File Format used for storing picture data. ... PCX is an image file format that uses a simple form of run-length encoding (a type of lossless compression algorithm). ... PGF (Progressive Graphics File) is a wavelet-based bitmapped image format that employs lossless and lossy data compression. ... Truevisions (now Pinnacle Systems) TGA File Format, often referred to as TARGA File Format, is a raster graphics file format. ... “TIFF” redirects here. ... HD Photo (formerly Windows Media Photo) is a still image compression algorithm and file format for continuous tone photographic images, developed by Microsoft as a part of the Windows Media family. ... A container format is a computer file format that can contain various types of data, compressed by means of standardized codecs. ... 3GP is a multimedia container format defined by the Third Generation Partnership Project (3GPP) for use on 3G mobile phones. ... Advanced Systems Format (formerly Advanced Streaming Format) is Microsofts proprietary digital audio/digital video container format, especially meant for streaming media. ... // Audio-Video Interleaved, known by its acronym AVI, is a multimedia container format introduced by Microsoft in November 1992 as part of its Video for Windows technology. ... DivX is a video codec created by DivX, Inc. ... DPX, the short form of Digital Picture Exchange, is a common file format for digital film work and is an ANSI/SMPTE standard (268M-2003). ... Flash Video (FLV) is a proprietary file format used to deliver video over the Internet using Adobe Flash Player (formerly known as Macromedia Flash Player) version 6, 7, 8, or 9. ... The Matroska Multimedia Container is an open standard free multimedia container format that can hold an unlimited [1] number of video, audio, picture or subtitle tracks inside a single file. ... MPEG-4 Part 14, formally ISO/IEC 14496-14:2003, is a multimedia container format standard specified as a part of MPEG-4. ... Material eXchange Format (MXF) is a container format for professional digital video and audio media defined by a set of SMPTE standards. ... NUT is a patent-free, multimedia container format originally conceived by a few MPlayer and FFmpeg developers that were dissatisfied with the limitations of all currently available multimedia container formats such as AVI or Matroska. ... Ogg is an open standard for a free container format for digital multimedia, unrestricted by software patents and designed for efficient streaming and manipulation. ... Ogg Media (OGM), meaning Ogg Media File, is a container format (for video, audio and subtitle streams). ... QuickTime is a multimedia framework developed by Apple Inc. ... RealMedia is a multimedia container format created by RealNetworks. ... A VOB file (DVD-Video Object or Versioned Object Base) is a container format contained in DVD-Video media. ... Audio Interchange File Format (AIFF) is an audio file format standard used for storing sound data on personal computers. ... The Au file format is a simple audio file format that consists of a header of 6 32-bit words and then the data (high-order byte comes first). ... WAV (or WAVE), short for Waveform audio format, is a Microsoft and IBM audio file format standard for storing audio on PCs. ...