1.
Software developer
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A software developer is a person concerned with facets of the software development process, including the research, design, programming, and testing of computer software. Other job titles which are used with similar meanings are programmer, software analyst. According to developer Eric Sink, the differences between system design, software development, and programming are more apparent, even more so that developers become systems architects, those who design the multi-leveled architecture or component interactions of a large software system. In a large company, there may be employees whose sole responsibility consists of one of the phases above. In smaller development environments, a few people or even an individual might handle the complete process. The word software was coined as a prank as early as 1953, before this time, computers were programmed either by customers, or the few commercial computer vendors of the time, such as UNIVAC and IBM. The first company founded to provide products and services was Computer Usage Company in 1955. The software industry expanded in the early 1960s, almost immediately after computers were first sold in mass-produced quantities, universities, government, and business customers created a demand for software. Many of these programs were written in-house by full-time staff programmers, some were distributed freely between users of a particular machine for no charge. Others were done on a basis, and other firms such as Computer Sciences Corporation started to grow. The computer/hardware makers started bundling operating systems, systems software and programming environments with their machines, new software was built for microcomputers, so other manufacturers including IBM, followed DECs example quickly, resulting in the IBM AS/400 amongst others. The industry expanded greatly with the rise of the computer in the mid-1970s. In the following years, it created a growing market for games, applications. DOS, Microsofts first operating system product, was the dominant operating system at the time, by 2014 the role of cloud developer had been defined, in this context, one definition of a developer in general was published, Developers make software for the world to use. The job of a developer is to crank out code -- fresh code for new products, code fixes for maintenance, code for business logic, bus factor Software Developer description from the US Department of Labor
2.
Software release life cycle
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Usage of the alpha/beta test terminology originated at IBM. As long ago as the 1950s, IBM used similar terminology for their hardware development, a test was the verification of a new product before public announcement. B test was the verification before releasing the product to be manufactured, C test was the final test before general availability of the product. Martin Belsky, a manager on some of IBMs earlier software projects claimed to have invented the terminology, IBM dropped the alpha/beta terminology during the 1960s, but by then it had received fairly wide notice. The usage of beta test to refer to testing done by customers was not done in IBM, rather, IBM used the term field test. Pre-alpha refers to all activities performed during the project before formal testing. These activities can include requirements analysis, software design, software development, in typical open source development, there are several types of pre-alpha versions. Milestone versions include specific sets of functions and are released as soon as the functionality is complete, the alpha phase of the release life cycle is the first phase to begin software testing. In this phase, developers generally test the software using white-box techniques, additional validation is then performed using black-box or gray-box techniques, by another testing team. Moving to black-box testing inside the organization is known as alpha release, alpha software can be unstable and could cause crashes or data loss. Alpha software may not contain all of the features that are planned for the final version, in general, external availability of alpha software is uncommon in proprietary software, while open source software often has publicly available alpha versions. The alpha phase usually ends with a freeze, indicating that no more features will be added to the software. At this time, the software is said to be feature complete, Beta, named after the second letter of the Greek alphabet, is the software development phase following alpha. Software in the stage is also known as betaware. Beta phase generally begins when the software is complete but likely to contain a number of known or unknown bugs. Software in the phase will generally have many more bugs in it than completed software, as well as speed/performance issues. The focus of beta testing is reducing impacts to users, often incorporating usability testing, the process of delivering a beta version to the users is called beta release and this is typically the first time that the software is available outside of the organization that developed it. Beta version software is useful for demonstrations and previews within an organization
3.
Operating system
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An operating system is system software that manages computer hardware and software resources and provides common services for computer programs. All computer programs, excluding firmware, require a system to function. Operating systems are found on many devices that contain a computer – from cellular phones, the dominant desktop operating system is Microsoft Windows with a market share of around 83. 3%. MacOS by Apple Inc. is in place, and the varieties of Linux is in third position. Linux distributions are dominant in the server and supercomputing sectors, other specialized classes of operating systems, such as embedded and real-time systems, exist for many applications. A single-tasking system can run one program at a time. Multi-tasking may be characterized in preemptive and co-operative types, in preemptive multitasking, the operating system slices the CPU time and dedicates a slot to each of the programs. Unix-like operating systems, e. g. Solaris, Linux, cooperative multitasking is achieved by relying on each process to provide time to the other processes in a defined manner. 16-bit versions of Microsoft Windows used cooperative multi-tasking, 32-bit versions of both Windows NT and Win9x, used preemptive multi-tasking. Single-user operating systems have no facilities to distinguish users, but may allow multiple programs to run in tandem, a distributed operating system manages a group of distinct computers and makes them appear to be a single computer. The development of networked computers that could be linked and communicate with each other gave rise to distributed computing, distributed computations are carried out on more than one machine. When computers in a work in cooperation, they form a distributed system. The technique is used both in virtualization and cloud computing management, and is common in large server warehouses, embedded operating systems are designed to be used in embedded computer systems. They are designed to operate on small machines like PDAs with less autonomy and they are able to operate with a limited number of resources. They are very compact and extremely efficient by design, Windows CE and Minix 3 are some examples of embedded operating systems. A real-time operating system is a system that guarantees to process events or data by a specific moment in time. A real-time operating system may be single- or multi-tasking, but when multitasking, early computers were built to perform a series of single tasks, like a calculator. Basic operating system features were developed in the 1950s, such as resident monitor functions that could run different programs in succession to speed up processing
4.
Audio codec
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An audio codec is a device or computer program capable of coding or decoding a digital data stream of audio. In software, a codec is a computer program implementing an algorithm that compresses and decompresses digital audio data according to a given audio file or streaming media audio coding format. The objective of the algorithm is to represent the high-fidelity audio signal with minimum number of bits while retaining the quality and this can effectively reduce the storage space and the bandwidth required for transmission of the stored audio file. Most codecs are implemented as libraries which interface to one or more multimedia players, in hardware, audio codec refers to a single device that encodes analog audio as digital signals and decodes digital back into analog. In other words, it both an analog-to-digital converter and digital-to-analog converter running off the same clock. This is used in cards that support both audio in and out, for instance. Comparison of audio formats List of codecs Open source codecs and containers Transcoding Video codec
5.
Software license
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A software license is a legal instrument governing the use or redistribution of software. Under United States copyright law all software is copyright protected, in code as also object code form. The only exception is software in the public domain, most distributed software can be categorized according to its license type. Two common categories for software under copyright law, and therefore with licenses which grant the licensee specific rights, are proprietary software and free, unlicensed software outside the copyright protection is either public domain software or software which is non-distributed, non-licensed and handled as internal business trade secret. Contrary to popular belief, distributed unlicensed software is copyright protected. Examples for this are unauthorized software leaks or software projects which are placed on public software repositories like GitHub without specified license. As voluntarily handing software into the domain is problematic in some international law domains, there are also licenses granting PD-like rights. Therefore, the owner of a copy of software is legally entitled to use that copy of software. Hence, if the end-user of software is the owner of the respective copy, as many proprietary licenses only enumerate the rights that the user already has under 17 U. S. C. §117, and yet proclaim to take away from the user. Proprietary software licenses often proclaim to give software publishers more control over the way their software is used by keeping ownership of each copy of software with the software publisher. The form of the relationship if it is a lease or a purchase, for example UMG v. Augusto or Vernor v. Autodesk. The ownership of goods, like software applications and video games, is challenged by licensed. The Swiss based company UsedSoft innovated the resale of business software and this feature of proprietary software licenses means that certain rights regarding the software are reserved by the software publisher. Therefore, it is typical of EULAs to include terms which define the uses of the software, the most significant effect of this form of licensing is that, if ownership of the software remains with the software publisher, then the end-user must accept the software license. In other words, without acceptance of the license, the end-user may not use the software at all, one example of such a proprietary software license is the license for Microsoft Windows. The most common licensing models are per single user or per user in the appropriate volume discount level, Licensing per concurrent/floating user also occurs, where all users in a network have access to the program, but only a specific number at the same time. Another license model is licensing per dongle which allows the owner of the dongle to use the program on any computer, Licensing per server, CPU or points, regardless the number of users, is common practice as well as site or company licenses
6.
Data compression
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In signal processing, data compression, source coding, or bit-rate reduction involves encoding information using fewer bits than the original representation. Compression can be 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, the process of reducing the size of a data file is referred to as data compression. In the context of data transmission, it is called coding in opposition to channel coding. Compression is useful because it reduces resources required to store and transmit data, computational resources are consumed in the compression process and, usually, in the reversal of the process. Data compression is subject to a space–time complexity trade-off, Lossless data compression algorithms usually exploit statistical redundancy to represent data without losing any information, so that the process is reversible. Lossless compression is possible because most real-world data exhibits statistical redundancy, for example, an image may have areas of color that do not change over several pixels, instead of coding red pixel, red pixel. The data may be encoded as 279 red pixels and this is a basic example of run-length encoding, there are many schemes to reduce file size by eliminating redundancy. The Lempel–Ziv compression methods are among the most popular algorithms for lossless storage, DEFLATE is a variation on LZ optimized for decompression speed and compression ratio, but compression can be slow. DEFLATE is used in PKZIP, Gzip, and PNG, LZW is used in GIF images. LZ methods use a table-based compression model where table entries are substituted for repeated strings of data, for most LZ methods, this table is generated dynamically from earlier data in the input. The table itself is often Huffman encoded, current LZ-based coding schemes that perform well are Brotli and LZX. LZX is used in Microsofts CAB format, the best modern lossless compressors use probabilistic models, such as prediction by partial matching. The Burrows–Wheeler transform can also be viewed as a form of statistical modelling. The basic task of grammar-based codes is constructing a context-free grammar deriving a single string, sequitur and Re-Pair are practical grammar compression algorithms for which software is publicly available. In a further refinement of the use of probabilistic modelling. Arithmetic coding is a more modern coding technique that uses the mathematical calculations of a machine to produce a string of encoded bits from a series of input data symbols
7.
Compact disc
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Compact disc is a digital optical disc data storage format released in 1982 and co-developed by Philips and Sony. The format was developed to store and play only sound recordings but was later adapted for storage of data. The first commercially available Audio CD player, the Sony CDP-101, was released October 1982 in Japan, standard CDs have a diameter of 120 millimetres and can hold up to about 80 minutes of uncompressed audio or about 700 MiB of data. The Mini CD has various diameters ranging from 60 to 80 millimetres, they are used for CD singles, storing up to 24 minutes of audio. At the time of the introduction in 1982, a CD could store much more data than a personal computer hard drive. By 2010, hard drives commonly offered as much space as a thousand CDs. In 2004, worldwide sales of audio CDs, CD-ROMs and CD-Rs reached about 30 billion discs, by 2007,200 billion CDs had been sold worldwide. In 2014, revenues from digital music services matched those from physical format sales for the first time. American inventor James T. Russell has been credited with inventing the first system to record information on an optical transparent foil that is lit from behind by a high-power halogen lamp. Russells patent application was first filed in 1966, and he was granted a patent in 1970, following litigation, Sony and Philips licensed Russells patents in the 1980s. The compact disc is an evolution of LaserDisc technology, where a laser beam is used that enables the high information density required for high-quality digital audio signals. Prototypes were developed by Philips and Sony independently in the late 1970s, although originally dismissed by Philips Research management as a trivial pursuit, the CD became the primary focus for Philips as the LaserDisc format struggled. In 1979, Sony and Philips set up a joint task force of engineers to design a new audio disc. After a year of experimentation and discussion, the Red Book CD-DA standard was published in 1980, after their commercial release in 1982, compact discs and their players were extremely popular. Despite costing up to $1,000, over 400,000 CD players were sold in the United States between 1983 and 1984, by 1988 CD sales in the United States surpassed those of vinyl LPs, and by 1992 CD sales surpassed those of prerecorded music cassette tapes. The success of the disc has been credited to the cooperation between Philips and Sony, who came together to agree upon and develop compatible hardware. The unified design of the disc allowed consumers to purchase any disc or player from any company. In 1974, L. However, due to the performance of the analog format
8.
Hertz
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The hertz is the unit of frequency in the International System of Units and is defined as one cycle per second. It is named for Heinrich Rudolf Hertz, the first person to provide proof of the existence of electromagnetic waves. Hertz are commonly expressed in SI multiples kilohertz, megahertz, gigahertz, kilo means thousand, mega meaning million, giga meaning billion and tera for trillion. Some of the units most common uses are in the description of waves and musical tones, particularly those used in radio-. It is also used to describe the speeds at which computers, the hertz is equivalent to cycles per second, i. e. 1/second or s −1. In English, hertz is also used as the plural form, as an SI unit, Hz can be prefixed, commonly used multiples are kHz, MHz, GHz and THz. One hertz simply means one cycle per second,100 Hz means one hundred cycles per second, and so on. The unit may be applied to any periodic event—for example, a clock might be said to tick at 1 Hz, the rate of aperiodic or stochastic events occur is expressed in reciprocal second or inverse second in general or, the specific case of radioactive decay, becquerels. Whereas 1 Hz is 1 cycle per second,1 Bq is 1 aperiodic radionuclide event per second, the conversion between a frequency f measured in hertz and an angular velocity ω measured in radians per second is ω =2 π f and f = ω2 π. This SI unit is named after Heinrich Hertz, as with every International System of Units unit named for a person, the first letter of its symbol is upper case. Note that degree Celsius conforms to this rule because the d is lowercase. — Based on The International System of Units, the hertz is named after the German physicist Heinrich Hertz, who made important scientific contributions to the study of electromagnetism. The name was established by the International Electrotechnical Commission in 1930, the term cycles per second was largely replaced by hertz by the 1970s. One hobby magazine, Electronics Illustrated, declared their intention to stick with the traditional kc. Mc. etc. units, sound is a traveling longitudinal wave which is an oscillation of pressure. Humans perceive frequency of waves as pitch. Each musical note corresponds to a frequency which can be measured in hertz. An infants ear is able to perceive frequencies ranging from 20 Hz to 20,000 Hz, the range of ultrasound, infrasound and other physical vibrations such as molecular and atomic vibrations extends from a few femtoHz into the terahertz range and beyond. Electromagnetic radiation is described by its frequency—the number of oscillations of the perpendicular electric and magnetic fields per second—expressed in hertz. Radio frequency radiation is measured in kilohertz, megahertz, or gigahertz
9.
Pulse-code modulation
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Pulse-code modulation is a method used to digitally represent sampled analog signals. It is the form of digital audio in computers, compact discs, digital telephony. In a PCM stream, the amplitude of the signal is sampled regularly at uniform intervals. Linear pulse-code modulation is a type of PCM where the quantization levels are linearly uniform. This is in contrast to PCM encodings where quantization levels vary as a function of amplitude, though PCM is a more general term, it is often used to describe data encoded as LPCM. Early electrical communications started to sample signals in order to interlace samples from multiple telegraphy sources, the American inventor Moses G. Farmer conveyed telegraph time-division multiplexing as early as 1853. Electrical engineer W. M. Miner, in 1903, used an electro-mechanical commutator for time-division multiplexing multiple telegraph signals and he obtained intelligible speech from channels sampled at a rate above 3500–4300 Hz, lower rates proved unsatisfactory. This was TDM, but pulse-amplitude modulation rather than PCM, in 1920 the Bartlane cable picture transmission system, named after its inventors Harry G. Bartholomew and Maynard D. In 1926, Paul M. Rainey of Western Electric patented a machine which transmitted its signal using 5-bit PCM. The machine did not go into production, british engineer Alec Reeves, unaware of previous work, conceived the use of PCM for voice communication in 1937 while working for International Telephone and Telegraph in France. He described the theory and advantages, but no practical application resulted, Reeves filed for a French patent in 1938, and his US patent was granted in 1943. By this time Reeves had started working at the Telecommunications Research Establishment, the first transmission of speech by digital techniques, the SIGSALY encryption equipment, conveyed high-level Allied communications during World War II. In 1943 the Bell Labs researchers who designed the SIGSALY system became aware of the use of PCM binary coding as already proposed by Alec Reeves. In 1949 for the Canadian Navys DATAR system, Ferranti Canada built a working PCM radio system that was able to transmit digitized radar data over long distances, PCM in the late 1940s and early 1950s used a cathode-ray coding tube with a plate electrode having encoding perforations. The plate collected or passed the beam, producing current variations in binary code, rather than natural binary, the grid of Goodalls later tube was perforated to produce a glitch-free Gray code, and produced all bits simultaneously by using a fan beam instead of a scanning beam. Patent 2,801,281 filed in 1946 and 1952, another patent by the same title was filed by John R. Pierce in 1945, and issued in 1948, U. S. The three of them published The Philosophy of PCM in 1948, PCM is the method of encoding generally used for uncompressed audio, although there are other methods such as pulse-density modulation. The 4ESS switch introduced time-division switching into the US telephone system in 1976, LPCM is used for the lossless encoding of audio data in the Compact disc Red Book standard, introduced in 1982
10.
FLAC
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FLAC is an audio coding format for lossless compression of digital audio, and is also the name of the reference codec implementation. Digital audio compressed by FLACs algorithm can typically be reduced to 50–60% of its original size, FLAC is an open format with royalty-free licensing and a reference implementation which is free software. FLAC has support for metadata tagging, album art. Development was started in 2000 by Josh Coalson, the bit-stream format was frozen when FLAC entered beta stage with the release of version 0.5 of the reference implementation on 15 January 2001. Version 1.0 was released on 20 July 2001, on 29 January 2003, the Xiph. Org Foundation and the FLAC project announced the incorporation of FLAC under the Xiph. org banner. Xiph. org is behind other free compression formats such as Vorbis, Theora, Speex and Opus. Version 1.3.0 was released on 26 May 2013, at which point development was moved to the Xiph. org git repository. flac files, the reference implementation is free software. The source code for libFLAC and libFLAC++ is available under the BSD license, and the sources for flac, metaflac, in its stated goals, the FLAC project encourages its developers not to implement copy prevention features of any kind. FLAC supports only fixed-point samples, not floating-point and it can handle any PCM bit resolution from 4 to 32 bits per sample, any sampling rate from 1 Hz to 655,350 Hz in 1 Hz increments, and any number of channels from 1 to 8. Channels can be grouped in some cases, for stereo and 5.1 channel surround. FLAC uses CRC checksums for identifying corrupted frames when used in a streaming protocol, FLAC allows for a Rice parameter between 0 and 16. FLAC uses linear prediction to convert the audio samples, there are two steps, the predictor and the error coding. The predictor can be one of four types, the difference between the predictor and the actual sample data is calculated and is known as the residual. The residual is stored efficiently using Golomb-Rice coding and it also uses run-length encoding for blocks of identical samples, such as silent passages. For tagging, FLAC uses the system as Vorbis comments. The libFLAC API is organized into streams, seekable streams, most FLAC applications will generally restrict themselves to encoding/decoding using libFLAC at the file level interface. LibFLAC uses a compression level parameter that varies from 0 to 8, the compressed files are always perfect, lossless representations of the original data. Although the compression process involves a tradeoff between speed and size, the process is always quite fast and not very dependent on the level of compression
11.
Rockbox
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Rockbox is a free and open-source software replacement for the OEM firmware in various forms of digital audio players with an original kernel. It offers an alternative to the operating system, in many cases without removing the original firmware. Enhancements include personal digital assistant functions, applications, utilities, Rockbox can also retrofit video playback functions on players first released in mid-2000. Rockbox includes a voice-driven user-interface suitable for operation by visually impaired users and these devices have relatively weak main central processing units, and instead offload music playback to dedicated hardware MP3 decoding chips. Rockbox was unable to alter playback abilities. Instead, it offered an improved user interface and added plug-in functions absent in the factory firmware. Rockbox can be flashed into flash memory on the Archos devices. Versions of Rockbox have since produced for more sophisticated devices. Rockbox is run from the drive or flash memory after being started with a custom boot loader, so to upgrade Rockbox, users need only copy the files onto the players drive. Reflashing is only needed when changing the boot loader, and on platforms is not needed at all. The first of ports, beginning in late 2004, was for the ColdFire-powered devices manufactured by iriver. About one year later, a port for the H3xx series became functional, in late 2005, work began on a port of Rockbox to Apples iPod portable players based on CPUs from ARM Ltd. incorporated into systems on a chip sold by PortalPlayer. Throughout 2006, Rockbox ports were available for a variety of iPod models. During this time, extensive work was conducted optimizing open source audio decoders for each of the ARM series processors, in 2008, porting began to processors based on the MIPS architecture. In 2010, work began on supporting hosted architectures where Rockbox runs as an application inside of more complex operating system, to date, all Rockbox ports have been accomplished by reverse engineering with little or no manufacturer assistance. As free software, many Rockbox developers and supporters hope to see official manufacturer support for new ports. Only a few companies have expressed interest in Rockbox, and none have officially contributed code to the project or included it with their hardware. The Sansa e200v1 port is the first to be started at the request of the hardware manufacturer, Rockbox is continuously developed, with new Git builds being released after every source change, and stable releases every 4 months for targets deemed sufficiently mature
12.
Nero Burning ROM
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Nero Burning ROM, commonly called Nero, is an optical disc authoring program from Nero AG. The software is part of the Nero Multimedia Suite but is available as a stand-alone product. It is used for burning and copying optical discs such as CDs, DVDs, the program also supports label printing technologies LightScribe and LabelFlash and can be used to convert audio files into other audio formats. Nero Burning ROM is a pun in reference to Roman Emperor Nero, the emperor allegedly fiddled while the city of Rome burned. Also, Rome in German is spelled Rom, the softwares logo features a burning Colosseum, although this is an anachronism as it was not built until after Neros death. Nero Burning ROM is only available for Microsoft Windows, a Linux-compatible version was available from 2005 to 2012, but it has since been discontinued. In newer versions, media can be added to compilations via the Nero MediaBrowser, Nero AirBurn, a new feature in Nero 2015, enables users to burn media straight from their mobile devices. The latest Version is Nero Burning ROM2017 released in October 2016 including SecurDisc 4.0 with 256-bit encryption, depending on the version, additional image formats may be supported. To use non-natively supported formats such as lossless FLAC, Wavpack, the modules are also known as plug-ins and codecs and are usually free, although Nero AG sells some proprietary video and audio plug-ins. Standard CD images created by Nero products have the filename extension. NRG, Nero Burning ROM is integrated in the Nero Multimedia Suite and is also available as a downloadable standalone product. It is also a part of Nero Essentials – a slimmed-down version of Nero Multimedia Suite – that comes bundled with OEM computers, note, Although Nero AG appears to no longer maintain a history of older versions on their website, release notes are archived by several third-party sites. InCD – drag and drop packet-writing software from Nero AG Nero Digital – a suite of MPEG-4 codecs developed by Nero AG List of optical disc authoring software Official website
13.
Winamp
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Since version 2 it has been sold as freemium and supports extensibility with plug-ins and skins, and features music visualization, playlist and a media library, supported by a large online community. Version 1 of Winamp was released in 1997, and grew popular with over 3 million downloads. Winamp 2.0 was released on September 8,1998, the 2. x versions were widely used and made Winamp one of the most downloaded Windows applications. By 2000, Winamp had over 25 million registered users, a poor reception to the 2002 rewrite, Winamp3, was followed by the release of Winamp 5 in 2003, and a later release of version 5.5 in 2007. Playback formats Winamp supports music playback using MP3, MIDI, MOD, MPEG-1 audio layers 1 and 2, AAC, M4A, FLAC, WAV, Winamp was one of the first widely used music players on Windows to support playback of Ogg Vorbis by default. It supports gapless playback for MP3 and AAC and ReplayGain for volume leveling across tracks, CD support includes playing and importing music from audio CDs, optionally with CD-Text, and burning music to CDs. The standard version limits maximum speed and datarate, the Pro version removes these limitations. Winamp supports playback of Windows Media Video and Nullsoft Streaming Video, for MPEG Video, AVI, and other unsupported video types, Winamp uses Microsofts DirectShow API for playback, allowing playback of most of the video formats supported by Windows Media Player. 5.1 Surround sound is supported where formats and decoders allow, Media Library At installation, Winamp scans the users system for media files to add to the Media Library database. It supports full Unicode filenames and Unicode metadata for media files, in the Media Library user interface pane, under Local Media, several selectors permit display of subsets of media files with greater detail. Adding album art and track tags Get Album Art permits retrieval of cover art, autotagging analyzes a tracks audio using the Gracenote service and retrieves the songs ID2 and ID3 metadata. Podcatcher Winamp can also be used as an RSS media feeds aggregator capable of displaying articles, downloading, SHOUTcast Wire provides a directory and RSS subscription system for podcasts. Media Monitor Winamp Media Monitor allows web-based browsing and bookmarking music blog websites, the Media Monitor is preloaded with music blog URLs. Winamp Remote Winamp Remote allows remote playback of unprotected media files on the users PC via the Internet, Remote adjusts bitrate based on available bandwidth, and can be controlled by web interface, Wii, PlayStation 3, Xbox 360, and mobile phones. Plug-ins In February 1998, Winamp was rewritten as an audio player with a plug-in architecture. This feature was received well by reviewers, development was early, diverse, and rapid,66 plugins were published by November 1998. The Winamp software development kit allows developers to create seven different types of plug-ins. Input. Output, sends data to devices or files
14.
FFmpeg
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FFmpeg is a free software project that produces libraries and programs for handling multimedia data. FFmpeg is published under the GNU Lesser General Public License 2. 1+ or GNU General Public License 2+, the name of the project is inspired by the MPEG video standards group, together with FF for fast forward. The logo uses a pattern that shows how MPEG video codecs handle entropy encoding. The project was started by Fabrice Bellard in 2000, and was led by Michael Niedermayer from 2004 until 2015, some FFmpeg developers were also part of the MPlayer project. The project publishes a new release every three months on average, on January 10,2014, two Google employees announced that over 1000 bugs had been fixed in FFmpeg during the previous two years by means of fuzz testing. Two video coding formats with corresponding codecs and one container format have been created within the FFmpeg project so far, the two video codecs are the lossless FFV1, and the lossless and lossy Snow codec. Development of Snow has stalled, while its bit-stream format has not been finalized yet, the multimedia container format called NUT is no longer being actively developed, but still maintained. In summer 2010, Fiona Glaser, Ronald Bultje, and David Conrad of the FFmpeg Team announced the ffvp8 decoder, through testing, they determined that ffvp8 was faster than Googles own libvpx decoder. Starting with version 0.6, FFmpeg also supported WebM, in October 2013, a native VP9 and the OpenHEVC decoder, an open source High Efficiency Video Coding decoder, were added to FFmpeg. In 2016 the native AAC encoder was considered stable, removing support for the two external AAC encoders from VisualOn and FAAC, FFmpeg 3.0 retained build support for the Fraunhofer FDK AAC encoder. Ffmpeg is a tool that converts audio or video formats. It can also capture and encode in real-time from various hardware and software such as a TV capture card. Ffserver is an HTTP and RTSP multimedia streaming server for live and it can also be used to time shift live broadcasts. Ffplay is a media player utilizing SDL and the FFmpeg libraries. Ffprobe is a tool to display media information, see also Mediainfo. Libswresample is a library containing audio resampling routines, libavresample is a library containing audio resampling routines from the Libav project, similar to libswresample from ffmpeg. Libavcodec is a library containing all of the native FFmpeg audio/video encoders and decoders, most codecs were developed from scratch to ensure best performance and high code reusability. Libavformat is a library containing demuxers and muxers for audio/video container formats, libavutil is a helper library containing routines common to different parts of FFmpeg
15.
Libav
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Libav is a free software project, forked from FFmpeg in 2011, that produces libraries and programs for handling multimedia data. Libav is developed for many operating systems, including GNU/Linux, the BSDs, macOS, Microsoft Windows, AmigaOS and it supports most common instruction set architectures, including IA-32, x86-64, PowerPC, ARM, DEC Alpha, SPARC, and MIPS. The Libav project is a fork of the FFmpeg project which was started by Fabrice Bellard. The Libav project was announced on March 13,2011 by a group of FFmpeg developers, the maintainer of the FFmpeg packages for Debian and Ubuntu, being one of the group of developers who forked FFmpeg, switched the packages to this fork in 2011. Hence, most software on these systems that depended on FFmpeg automatically switched to Libav, in July 8,2015, Debian announced it would return to FFmpeg for various, technical reasons. FFmpeg first had a record of responding to vulnerabilities than Libav. Finally, the gap between FFmpeg and Libav, with FFmpeg supporting a far wider variety of codecs and containers than Libav does. It has been suggested to merge the two back into each other but this has not happened. With Debian and Ubuntu no longer using Libav, its future might be compromised, at the beginning of this fork, Libav and FFmpeg separately developed their own versions of the ffmpeg command. Libav then renamed their ffmpeg to avconv to distance themselves from the FFmpeg project, during the transition period, when a Libav user typed ffmpeg, there was a message telling the user that the ffmpeg command was deprecated and avconv has to be used instead. This confused some users into thinking that FFmpeg was dead and this message was removed upstream when ffmpeg was finally removed from the Libav sources. In June 2012, on Ubuntu 12.04, the message was re-worded, starting with Ubuntu 15.04 Vivid, FFmpegs ffmpeg is back in the repositories again. To further complicate matters, Libav chose a name that was used by FFmpeg to refer to its libraries, for example, the libav-user mailing list, for questions and discussions about using the FFmpeg libraries, is unrelated to the Libav project. Debian followed Libav when it was announced, and announced it would return to FFmpeg for Debian Stretch, gentoo users are free to choose between FFmpeg and Libav by the way they install their virtual FFmpeg. MPlayer2, a fork of MPlayer, used Libav exclusively. GStreamer can however support Mplayer and Mplayer2 through different plugins, Libav contains more than 100 codecs. Many codecs that compress information have been claimed by patent holders, the Libav logo uses a zigzag pattern that references how MPEG video codecs handle entropy encoding. It was previously the logo of the FFmpeg project until Libav was forked from it, following the fork, in 2011 one of the Libav developers Måns Rullgård claimed copyright over the logo and requested FFmpeg cease and desist from using it
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Multimedia
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Multimedia is content that uses a combination of different content forms such as text, audio, images, animations, video and interactive content. Multimedia contrasts with media that use only rudimentary computer displays such as text-only or traditional forms of printed or hand-produced material, Multimedia devices are electronic media devices used to store and experience multimedia content. Multimedia is distinguished from mixed media in art, for example. The term rich media is synonymous with interactive multimedia, the term multimedia was coined by singer and artist Bob Goldstein to promote the July 1966 opening of his LightWorks at LOursin show at Southampton, Long Island. Goldstein was perhaps aware of an American artist named Dick Higgins, two years later, in 1968, the term multimedia was re-appropriated to describe the work of a political consultant, David Sawyer, the husband of Iris Sawyer—one of Goldsteins producers at LOursin. In the intervening forty years, the word has taken on different meanings, in the late 1970s, the term referred to presentations consisting of multi-projector slide shows timed to an audio track. However, by the 1990s multimedia took on its current meaning, in the 1993 first edition of Multimedia, Making It Work, Tay Vaughan declared Multimedia is any combination of text, graphic art, sound, animation, and video that is delivered by computer. When you allow the user – the viewer of the project – to control what, when you provide a structure of linked elements through which the user can navigate, interactive multimedia becomes hypermedia. The German language society Gesellschaft für deutsche Sprache recognized the words significance, the institute summed up its rationale by stating has become a central word in the wonderful new media world. In common usage, multimedia refers to an electronically delivered combination of media including video, still images, audio, much of the content on the web today falls within this definition as understood by millions. That era saw also a boost in the production of educational multimedia CD-ROMs, the term video, if not used exclusively to describe motion photography, is ambiguous in multimedia terminology. Video is often used to describe the format, delivery format. Multiple forms of content are often not considered modern forms of presentation such as audio or video. Likewise, single forms of content with single methods of information processing are often called multimedia. Performing arts may also be considered multimedia considering that performers and props are multiple forms of content and media. Multimedia presentations may be viewed by person on stage, projected, transmitted, a broadcast may be a live or recorded multimedia presentation. Broadcasts and recordings can be analog or digital electronic media technology. Digital online multimedia may be downloaded or streamed, streaming multimedia may be live or on-demand
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International Organization for Standardization
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The International Organization for Standardization is an international standard-setting body composed of representatives from various national standards organizations. Founded on 23 February 1947, the organization promotes worldwide proprietary and it is headquartered in Geneva, Switzerland, and as of March 2017 works in 162 countries. It was one of the first organizations granted general consultative status with the United Nations Economic, ISO, the International Organization for Standardization, is an independent, non-governmental organization, the members of which are the standards organizations of the 162 member countries. It is the worlds largest developer of international standards and facilitates world trade by providing common standards between nations. Nearly twenty thousand standards have been set covering everything from manufactured products and technology to food safety, use of the standards aids in the creation of products and services that are safe, reliable and of good quality. The standards help businesses increase productivity while minimizing errors and waste, by enabling products from different markets to be directly compared, they facilitate companies in entering new markets and assist in the development of global trade on a fair basis. The standards also serve to safeguard consumers and the end-users of products and services, the three official languages of the ISO are English, French, and Russian. The name of the organization in French is Organisation internationale de normalisation, according to the ISO, as its name in different languages would have different abbreviations, the organization adopted ISO as its abbreviated name in reference to the Greek word isos. However, during the meetings of the new organization, this Greek word was not invoked. Both the name ISO and the logo are registered trademarks, the organization today known as ISO began in 1926 as the International Federation of the National Standardizing Associations. ISO is an organization whose members are recognized authorities on standards. Members meet annually at a General Assembly to discuss ISOs strategic objectives, the organization is coordinated by a Central Secretariat based in Geneva. A Council with a membership of 20 member bodies provides guidance and governance. The Technical Management Board is responsible for over 250 technical committees, ISO has formed joint committees with the International Electrotechnical Commission to develop standards and terminology in the areas of electrical and electronic related technologies. Information technology ISO/IEC Joint Technical Committee 1 was created in 1987 to evelop, maintain, ISO has three membership categories, Member bodies are national bodies considered the most representative standards body in each country. These are the members of ISO that have voting rights. Correspondent members are countries that do not have their own standards organization and these members are informed about ISOs work, but do not participate in standards promulgation. Subscriber members are countries with small economies and they pay reduced membership fees, but can follow the development of standards
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International Electrotechnical Commission
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The IEC also manages three global conformity assessment systems that certify whether equipment, system or components conform to its International Standards. The first International Electrical Congress took place in 1881 at the International Exposition of Electricity, at that time the International System of Electrical and Magnetic Units was agreed to. The IEC was instrumental in developing and distributing standards for units of measurement, particularly Gauss, Hertz and it also first proposed a system of standards, the Giorgi System, which ultimately became the SI, or Système International d’unités. In 1938, it published a multilingual international vocabulary to unify terminology relating to electrical, electronic and this effort continues, and the International Electrotechnical Vocabulary remains an important work in the electrical and electronic industries. The CISPR – in English, the International Special Committee on Radio Interference – is one of the groups founded by the IEC, originally located in London, the commission moved to its current headquarters in Geneva in 1948. It has regional centres in Asia-Pacific, Latin America and North America, today, the IEC is the worlds leading international organization in its field, and its standards are adopted as national standards by its members. The work is done by some 10,000 electrical and electronics experts from industry, government, academia, test labs, IEC standards have numbers in the range 60000–79999 and their titles take a form such as IEC60417, Graphical symbols for use on equipment. Following the Dresden Agreement with CENELEC the numbers of older IEC standards were converted in 1997 by adding 60000, for example IEC27 became IEC60027. Standards of the 60000 series are also preceded by EN to indicate that the IEC standard is also adopted by CENELEC as a European standard. The IEC cooperates closely with the International Organization for Standardization and the International Telecommunication Union, Standards developed jointly with ISO such as ISO/IEC26300, ISO/IEC27001, and CASCO ISO/IEC17000 series, carry the acronym of both organizations. The use of the ISO/IEC prefix covers publications from ISO/IEC Joint Technical Committee 1 - Information Technology, as well as conformity assessment standards developed by ISO CASCO, other standards developed in cooperation between IEC and ISO are assigned numbers in the 80000 series, such as IEC 82045-1. IEC standards are also being adopted by other certifying bodies such as BSI, CSA, UL & ANSI/INCITS, SABS, SAI, SPC/GB, IEC standards adopted by other certifying bodies may have some noted differences from the original IEC standard. The IEC is made up of members, called national committees, national committees are constituted in different ways. Some NCs are public sector only, some are a combination of public and private sector, about 90% of those who prepare IEC standards work in industry
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MPEG-1
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MPEG-1 is a standard for lossy compression of video and audio. Today, MPEG-1 has become the most widely compatible lossy audio/video format in the world, perhaps the best-known part of the MPEG-1 standard is the MP3 audio format it introduced. The MPEG-1 standard is published as ISO/IEC11172 – Information technology—Coding of moving pictures, MPEG was formed to address the need for standard video and audio formats, and to build on H.261 to get better quality through the use of more complex encoding methods. Development of the MPEG-1 standard began in May 1988, fourteen video and fourteen audio codec proposals were submitted by individual companies and institutions for evaluation. The codecs were extensively tested for computational complexity and subjective quality and this specific bitrate was chosen for transmission over T-1/E-1 lines and as the approximate data rate of audio CDs. The codecs that excelled in testing were utilized as the basis for the standard and refined further, with additional features. The reported completion date of the MPEG-1 standard varies greatly, a complete draft standard was produced in September 1990. The draft standard was publicly available for purchase, the standard was finished with the 6 November 1992 meeting. The Berkeley Plateau Multimedia Research Group developed an MPEG-1 decoder in November 1992, due in part to the similarity between the two codecs, the MPEG-2 standard includes full backwards compatibility with MPEG-1 video, so any MPEG-2 decoder can play MPEG-1 videos. This means that MPEG-1 coding efficiency can vary depending on the encoder used. The first three parts of ISO/IEC11172 were published in August 1993, the ISO patent database lists one patent for ISO11172, US4,472,747, which expired in 2003. The near-complete draft of the MPEG-1 standard was publicly available as ISO CD11172 by December 6,1991, a May 2009 discussion on the whatwg mailing list mentioned US5,214,678 patent as possibly covering MPEG audio layer II. Filed in 1990 and published in 1993, this patent is now expired, most popular software for video playback includes MPEG-1 decoding, in addition to any other supported formats. The popularity of MP3 audio has established a massive installed base of hardware that can play back MPEG-1 Audio, virtually all digital audio devices can play back MPEG-1 Audio. Many millions have been sold to-date, before MPEG-2 became widespread, many digital satellite/cable TV services used MPEG-1 exclusively. The widespread popularity of MPEG-2 with broadcasters means MPEG-1 is playable by most digital cable and satellite set-top boxes, MPEG-1 was used for full-screen video on Green Book CD-i, and on Video CD. The Super Video CD standard, based on VCD, uses MPEG-1 audio exclusively, the DVD-Video format uses MPEG-2 video primarily, but MPEG-1 support is explicitly defined in the standard. The DVD-Video standard originally required MPEG-1 Layer II audio for PAL countries, MPEG-1 Layer II audio is still allowed on DVDs, although newer extensions to the format, like MPEG Multichannel, are rarely supported
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MPEG-2
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MPEG-2 is a standard for the generic coding of moving pictures and associated audio information. MPEG-2 is widely used as the format of television signals that are broadcast by terrestrial, cable. It also specifies the format of movies and other programs that are distributed on DVD, TV stations, TV receivers, DVD players, and other equipment are often designed to this standard. MPEG-2 was the second of several developed by the Moving Pictures Expert Group and is an international standard. Parts 1 and 2 of MPEG-2 were developed in a collaboration with ITU-T, while MPEG-2 is the core of most digital television and DVD formats, it does not completely specify them. Regional institutions can adapt it to their needs by restricting and augmenting aspects of the standard, MPEG-2 includes a Systems section, part 1, that defines two distinct, but related, container formats. Program stream exceptions are M2TS, which is used on Blu-ray discs, AVCHD on re-writable DVDs, while VOB on DVDs and Enhanced VOB on the short lived HD DVD do not waste storage space and just use the program stream. MPEG-2 Systems is formally known as ISO/IEC 13818-1 and as ITU-T Rec, ISO authorized the SMPTE Registration Authority, LLC as the registration authority for MPEG-2 format identifiers. This provision will permit the MPEG-2 transport standard to all types of data while providing for a method of unambiguous identification of the characteristics of the underlying private data. The Video section, part 2 of MPEG-2, is similar to the previous MPEG-1 standard, but also support for interlaced video. MPEG-2 video is not optimized for low bit-rates, especially less than 1 Mbit/s at standard definition resolutions, all standards-compliant MPEG-2 Video decoders are fully capable of playing back MPEG-1 Video streams conforming to the Constrained Parameters Bitstream syntax. MPEG-2/Video is formally known as ISO/IEC 13818-2 and as ITU-T Rec, with some enhancements, MPEG-2 Video and Systems are also used in some HDTV transmission systems, and is the standard format for over-the-air ATSC digital television.1 multichannel. This method is backwards-compatible, allowing MPEG-1 audio decoders to decode the two main components of the presentation. MPEG-2 part 3 also defined additional bit rates and sample rates for MPEG-1 Audio Layer I, MPEG-2 BC low bitrate encoding with halved sampling rate multichannel encoding with up to 5.1 channels, a. k. a. MPEG Multichannel Part 7 of the MPEG-2 standard specifies a rather different, Part 7 is referred to as MPEG-2 AAC. AAC is more efficient than the previous MPEG audio standards, and is in some ways less complicated than its predecessor, MPEG-1 Audio, Layer 3, in that it does not have the hybrid filter bank. It supports from 1 to 48 channels at sampling rates of 8 to 96 kHz, with multichannel, multilingual, advanced Audio is also defined in Part 3 of the MPEG-4 standard. MPEG-2 NBC MPEG-2 AAC multichannel encoding with up to 48 channels MPEG-2 standards are published as parts of ISO/IEC13818, each part covers a certain aspect of the whole specification
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H.262/MPEG-2 Part 2
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H.262 or MPEG-2 Part 2 is a video coding format developed and maintained jointly by ITU-T Video Coding Experts Group and ISO/IEC Moving Picture Experts Group. It is the part of the ISO/IEC MPEG-2 standard. The ITU-T Recommendation H.262 and ISO/IEC 13818-2 documents are identical, the standard is available for a fee from the ITU-T and ISO. MPEG-2 Video is similar to MPEG-1, but also support for interlaced video. MPEG-2 video is not optimized for low bit-rates, but outperforms MPEG-1 at 3 Mbit/s, all standards-conforming MPEG-2 Video decoders are fully capable of playing back MPEG-1 Video streams. The ISO/IEC approval process was completed in November 1994, the first edition was approved in July 1995 and published by ITU-T and ISO/IEC in 1996. In 1996 it was extended by two amendments to include the Registration of Copyright Identifiers and the 4,2,2 Profile, ITU-T published these amendments in 1996 and ISO in 1997. There are also other amendments published later by ITU-T and ISO, the most recent edition of the standard was published in 2013 and incorporates all prior amendments. An HDTV camera generates a raw video stream of 149,299,200 bytes per second for 24fps video and this stream must be compressed if digital TV is to fit in the bandwidth of available TV channels and if movies are to fit on DVDs. Fortunately, video compression is practical because the data in pictures is often redundant in space, for example, the sky can be blue across the top of a picture and that blue sky can persist for frame after frame. Also, because of the way the eye works, it is possible to some data from video pictures with almost no noticeable degradation in image quality. TV cameras used in broadcasting usually generate 50 pictures a second or 59.94 pictures a second, digital television requires that these pictures be digitized so that they can be processed by computer hardware. Each picture element is represented by one luma number and two chrominance numbers. These describe the brightness and the color of the pixel, thus, each digitized picture is initially represented by three rectangular arrays of numbers. Upon reception/decoding, the two fields are displayed alternately with the lines of one field interleaving between the lines of the field, this format is called interlaced video. The typical field rate is 50 or 59.94 fields per second, if the video is not interlaced, then it is called progressive video and each picture is a frame. Another common practice to reduce the rate is to thin out or subsample the two chrominance planes. In effect, the chrominance values represent the nearby values that are deleted
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DV
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DV is a format for storing digital video. It was launched in 1995 with joint efforts of leading producers of video camera recorders, the original DV specification, known as Blue Book, was standardized within the IEC61834 family of standards. These standards define common features such as physical videocassettes, recording modulation method, magnetization, part 2 describes the specifics of 525-60 and 625-50 systems. The IEC standards are available as publications sold by IEC and ANSI, in 2003, DV was joined by a successor format HDV, which used the same tape format with a different video codec. Some cameras at the time had the ability to switch between DV and HDV recording modes, DV uses lossy compression of video while audio is stored uncompressed. An intraframe video compression scheme is used to video on a frame-by-frame basis with the discrete cosine transform. Closely following ITU-R Rec.601 standard, DV video employs interlaced scanning with the sampling frequency of 13.5 MHz. This results in 480 scanlines per complete frame for the 60 Hz system, in both systems the active area contains 720 pixels per scanline, with 704 pixels used for content and 16 pixels on the sides left for digital blanking. The same frame size is used for 4,3 and 16,9 frame aspect ratios, prior to the DCT compression stage, chroma subsampling is applied to the source video in order to reduce the amount of data to be compressed. Baseline DV uses 4,1,1 subsampling in its 60 Hz variant and 4,2,0 subsampling in the 50 Hz variant. Audio can be stored in either of two forms, 16-bit Linear PCM stereo at 48 kHz sampling rate, or four nonlinear 12-bit PCM channels at 32 kHz sampling rate. In addition, the DV specification also supports 16-bit audio at 44.1 kHz, in practice, the 48 kHz stereo mode is used almost exclusively. The audio, video, and metadata are packaged into 80-byte Digital Interface Format blocks which are multiplexed into a 150-block sequence. DIF blocks are the units of DV streams and can be stored as computer files in raw form or wrapped in such file formats as Audio Video Interleave, QuickTime. One video frame is formed from either 10 or 12 such sequences, depending on scanning rate, which results in a rate of about 25 Mbit/s for video. When written to tape, each corresponds to one complete track. This means that the sound may be +/- ⅓ frame out of sync with the video, however, this is the maximum drift of the audio/video synchronization, it is not compounded throughout the recording. Sony and Panasonic created their versions of DV, which use the same compression scheme
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Society of Motion Picture and Television Engineers
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SMPTE Membership is open to any individual or organization with interest in the subject matter. SMPTE standards documents are copyrighted and may be purchased from the SMPTE website, standard documents may be purchased by the general public. Significant standards promulgated by SMPTE include, All film and television formats and media. The society sponsors many awards, the oldest of which are the SMPTE Progress Medal, the Samuel Warner Memorial Medal, SMPTE also has a number of student Chapters and sponsors scholarships for college students in the motion imaging disciplines. A group within the standards committees has begun to work on the definition of the SMPTE 3D Home Master. SMPTE, instituted in 1999, a committee for the foundations of Digital Cinema. The SMPTE presents awards to individuals for outstanding contributions in fields of the society, James Cameron Edwin Catmull Birney Dayton Clyde D. Smith Roderick Snell Dr. Kees Immink Stanley N. Baron William C. Miller Bernard J. Lechner Ray Dolby Harold E. Edgerton Vladimir K. Zworykin John G. Frayne Walt Disney Chuck Pagano James M. DeFilippis Bernard J. Lechner Stanley N. Baron William F. Schreiber Adrian Ettlinger Joseph A. Flaherty, goldmark W. R. G. Baker Albert Rose Charles Ginsburg Robert E. Shelby Arthur V. Loughren Otto H. Recent recipients are Andrew Laszlo James MacKay Dr. Roderick T. Swartz
