Digital audio is sound, recorded in, or converted into, digital form. In digital audio, the sound wave of the audio signal is encoded as numerical samples in continuous sequence. For example, in CD audio, samples are taken 44100 times per second each with 16 bit sample depth. Digital audio is the name for the entire technology of sound recording and reproduction using audio signals that have been encoded in digital form. Following significant advances in digital audio technology during the 1970s, it replaced analog audio technology in many areas of audio engineering and telecommunications in the 1990s and 2000s. In a digital audio system, an analog electrical signal representing the sound is converted with an analog-to-digital converter into a digital signal using pulse-code modulation; this digital signal can be recorded, edited and copied using computers, audio playback machines, other digital tools. When the sound engineer wishes to listen to the recording on headphones or loudspeakers, a digital-to-analog converter performs the reverse process, converting a digital signal back into an analog signal, sent through an audio power amplifier and to a loudspeaker.
Digital audio systems may include compression, storage and transmission components. Conversion to a digital format allows convenient manipulation, storage and retrieval of an audio signal. Unlike analog audio, in which making copies of a recording results in generation loss and degradation of signal quality, digital audio allows an infinite number of copies to be made without any degradation of signal quality. Digital audio technologies are used in the recording, mass-production, distribution of sound, including recordings of songs, instrumental pieces, sound effects, other sounds. Modern online music distribution depends on digital recording and data compression; the availability of music as data files, rather than as physical objects, has reduced the costs of distribution. Before digital audio, the music industry distributed and sold music by selling physical copies in the form of records and cassette tapes. With digital-audio and online distribution systems such as iTunes, companies sell digital sound files to consumers, which the consumer receives over the Internet.
An analog audio system converts physical waveforms of sound into electrical representations of those waveforms by use of a transducer, such as a microphone. The sounds are stored on an analog medium such as magnetic tape, or transmitted through an analog medium such as a telephone line or radio; the process is reversed for reproduction: the electrical audio signal is amplified and converted back into physical waveforms via a loudspeaker. Analog audio retains its fundamental wave-like characteristics throughout its storage, transformation and amplification. Analog audio signals are susceptible to noise and distortion, due to the innate characteristics of electronic circuits and associated devices. Disturbances in a digital system do not result in error unless the disturbance is so large as to result in a symbol being misinterpreted as another symbol or disturb the sequence of symbols, it is therefore possible to have an error-free digital audio system in which no noise or distortion is introduced between conversion to digital format, conversion back to analog.
A digital audio signal may optionally be encoded for correction of any errors that might occur in the storage or transmission of the signal. This technique, known as channel coding, is essential for broadcast or recorded digital systems to maintain bit accuracy. Eight-to-fourteen modulation is a channel code used in the audio compact disc. A digital audio system starts with an ADC; the ADC converts at a known bit resolution. CD audio, for example, has a sampling rate of 44.1 kHz, has 16-bit resolution for each stereo channel. Analog signals that have not been bandlimited must be passed through an anti-aliasing filter before conversion, to prevent the aliasing distortion, caused by audio signals with frequencies higher than the Nyquist frequency. A digital audio signal may be transmitted. Digital audio can be stored on a CD, a digital audio player, a hard drive, a USB flash drive, or any other digital data storage device; the digital signal may be altered through digital signal processing, where it may be filtered or have effects applied.
Sample-rate conversion including upsampling and downsampling may be used to conform signals that have been encoded with a different sampling rate to a common sampling rate prior to processing. Audio data compression techniques, such as MP3, Advanced Audio Coding, Ogg Vorbis, or FLAC, are employed to reduce the file size. Digital audio can be carried over digital audio interfaces such as AES3 or MADI. Digital audio can be carried over a network using audio over Ethernet, audio over IP or other streaming media standards and systems. For playback, digital audio must be converted back to an analog signal with a DAC which may use oversampling. Pulse-code modulation was invented by British scientist Alec Reeves in 1937 and was used in telecommunications applications long before its first use in commercial broadcast and recording. Commercial digital recording was pioneered in Japan by NHK and Nippon Columbia and their Denon brand, in the 1960s; the first commercial digital recordings were released in 1971.
The BBC began to experiment with digital audio in the 1960s. By the early 1970s, it had developed a 2-channel recorder
An integrated circuit or monolithic integrated circuit is a set of electronic circuits on one small flat piece of semiconductor material, silicon. The integration of large numbers of tiny transistors into a small chip results in circuits that are orders of magnitude smaller and faster than those constructed of discrete electronic components; the IC's mass production capability and building-block approach to circuit design has ensured the rapid adoption of standardized ICs in place of designs using discrete transistors. ICs are now used in all electronic equipment and have revolutionized the world of electronics. Computers, mobile phones, other digital home appliances are now inextricable parts of the structure of modern societies, made possible by the small size and low cost of ICs. Integrated circuits were made practical by mid-20th-century technology advancements in semiconductor device fabrication. Since their origins in the 1960s, the size and capacity of chips have progressed enormously, driven by technical advances that fit more and more transistors on chips of the same size – a modern chip may have many billions of transistors in an area the size of a human fingernail.
These advances following Moore's law, make computer chips of today possess millions of times the capacity and thousands of times the speed of the computer chips of the early 1970s. ICs have two main advantages over discrete circuits: performance. Cost is low because the chips, with all their components, are printed as a unit by photolithography rather than being constructed one transistor at a time. Furthermore, packaged ICs use much less material than discrete circuits. Performance is high because the IC's components switch and consume comparatively little power because of their small size and close proximity; the main disadvantage of ICs is the high cost to fabricate the required photomasks. This high initial cost means. An integrated circuit is defined as: A circuit in which all or some of the circuit elements are inseparably associated and electrically interconnected so that it is considered to be indivisible for the purposes of construction and commerce. Circuits meeting this definition can be constructed using many different technologies, including thin-film transistors, thick-film technologies, or hybrid integrated circuits.
However, in general usage integrated circuit has come to refer to the single-piece circuit construction known as a monolithic integrated circuit. Arguably, the first examples of integrated circuits would include the Loewe 3NF. Although far from a monolithic construction, it meets the definition given above. Early developments of the integrated circuit go back to 1949, when German engineer Werner Jacobi filed a patent for an integrated-circuit-like semiconductor amplifying device showing five transistors on a common substrate in a 3-stage amplifier arrangement. Jacobi disclosed cheap hearing aids as typical industrial applications of his patent. An immediate commercial use of his patent has not been reported; the idea of the integrated circuit was conceived by Geoffrey Dummer, a radar scientist working for the Royal Radar Establishment of the British Ministry of Defence. Dummer presented the idea to the public at the Symposium on Progress in Quality Electronic Components in Washington, D. C. on 7 May 1952.
He gave many symposia publicly to propagate his ideas and unsuccessfully attempted to build such a circuit in 1956. A precursor idea to the IC was to create small ceramic squares, each containing a single miniaturized component. Components could be integrated and wired into a bidimensional or tridimensional compact grid; this idea, which seemed promising in 1957, was proposed to the US Army by Jack Kilby and led to the short-lived Micromodule Program. However, as the project was gaining momentum, Kilby came up with a new, revolutionary design: the IC. Newly employed by Texas Instruments, Kilby recorded his initial ideas concerning the integrated circuit in July 1958 demonstrating the first working integrated example on 12 September 1958. In his patent application of 6 February 1959, Kilby described his new device as "a body of semiconductor material … wherein all the components of the electronic circuit are integrated." The first customer for the new invention was the US Air Force. Kilby won the 2000 Nobel Prize in Physics for his part in the invention of the integrated circuit.
His work was named an IEEE Milestone in 2009. Half a year after Kilby, Robert Noyce at Fairchild Semiconductor developed a new variety of integrated circuit, more practical than Kilby's implementation. Noyce's design was made of silicon. Noyce credited Kurt Lehovec of Sprague Electric for the principle of p–n junction isolation, a key concept behind the IC; this isolation allows each transistor to operate independently despite being part of the same piece of silicon. Fairchild Semiconductor was home of the first silicon-gate IC technology with self-aligned gates, the basis of all modern CMOS integrated circuits; the technology was developed by Italian physicist Federico Faggin in 1968. In 1970, he joined Intel in order to develop the first single-chip central processing unit microprocessor, the Intel 4004, for which he received the National Medal of Technology and Innovation in 2010; the 4004 was designed by Busicom's Masatoshi Shima and Intel's Ted Hoff in 1969, but it was Faggin's improved design in 1970 that made it a reality.
Advances in IC technology smaller features and la
The XLR connector is a style of electrical connector found on professional audio and stage lighting equipment. The connectors have between three and seven pins, they are most associated with balanced audio interconnection, including AES3 digital audio, but are used for lighting control, low-voltage power supplies, other applications. XLR connectors are available from a number of manufacturers and are covered by an international standard for dimensions, IEC 61076-2-103, they are superficially similar to the smaller DIN connector range, but are not physically compatible with them. A smaller version, the Mini XLR Connector, is used on smaller equipment; the XLR connector was invented by James H. Cannon, founder of Cannon Electric in Los Angeles and for this reason it was sometimes colloquially known as a Cannon plug or Cannon connector. Manufactured as the Cannon X series, by 1950 a latching mechanism was added and by 1955 a version surrounding the female contacts with a synthetic rubber polychloroprene insulation using the part number prefix XLR.
There was an XLP series which used a hard plastic insulation, but was otherwise the same. ITT Cannon manufactured XLR connectors in two locations Kanagawa and Melbourne, Australia; the Australian operation was sold to Alcatel Components in 1992 and acquired by Amphenol in 1998. ITT Cannon continues to manufacture XLR connectors in Japan; the Switchcraft corporation started manufacturing compatible connectors, followed by Neutrik. Neutrik made a number of improvements to the connector and its second-generation design had just four parts for the cable connector and eliminated the small screws used by both Cannon and Switchcraft, which were prone to working loose, falling out and becoming lost. XLR connectors are available in male and female versions in both cable and chassis mounting designs, a total of four styles; this is unusual as many other connector designs omit one of the styles. The female XLR connectors are designed to first connect pin 1, before the other pins make contact, when a male XLR connector is inserted.
With the ground connection established before the signal lines are connected, the insertion of XLR connectors in live equipment is possible without picking up external signals. The number of pins varies; as of 2016, XLR connectors are available with up to 10 pins, mini XLR connectors with up to eight. XLR connectors from different manufacturers will intermate, with the exception of six-pin models, which are available in two incompatible designs; the older Switchcraft 6 pin design adds a center pin to the standard 5 pin design, whereas the newer Neutrik design is a different pattern. The Switchcraft 6 pin female will accept a standard 5 pin male plug whereas the Neutrik 6 pin design will not. Neutrik offers connectors in both 6 pin designs; the terminology for labelling the corresponding members of a pair of mating connectors follows the usual rules for the gender of connectors: a'male' connector is the one with pins on the smallest element,'female' has corresponding receptacles. A'plug' connector enters the'socket' connector, judged by the largest element.
For most XLR, plugs are male and sockets are female. XLR are unusual as, at least in audio applications, all four combinations of male and female and sockets are common. A common misnomer is that'plugs' are free connectors and'sockets' are panel-mounted, but XLR uses many free female sockets and panel-mounted male plugs. There is a loose convention for audio work that signals are generated by equipment with male pins and transmitted to that with female receptacles. Three-pin XLR connectors are by far the most common style, are an industry standard for balanced audio signals; the great majority of professional microphones use the XLR connector. In previous years, they were used for loudspeaker connections, for instance by Trace Elliot in its bass enclosures; the XLR could accept 14 AWG wire with a current-carrying capacity of 15 amps, suitable for most loudspeakers, but they have been superseded by the Speakon connector for professional loudspeakers. The Speakon connector accepts larger wire and carries more current, it provides a better shield for the contacts, which may carry dangerous voltages when connected to an amplifier.
Three-pin XLR connectors are used to interconnect powered speakers with line-level signals. This use is seen in PA system applications and seems to be growing more common. Rechargeable devices exist; these can be found on electric powered mobility scooters. The connectors carry from 2 to 10 amps at 24 volts. An obsolete use for three-pin XLR connectors was for MIDI data on some Octave-Plateau synthesizers including the Voyetra-8; the three-pin XLR connector is used for DMX512, on lighting and related control equipment. At the budget / DJ end of the market. However, using three-pin XLR connectors for DMX512 is prohibited by section 7.1.2 of the DMX512 standard. Use of the three-pin XLR in this context firstly presents a risk of damage to the lighting equipment should an audio cable carrying 48 volt phantom power be accidentally connected, secondly encourages the use of cable following analogue audio specifications for DMX, which can lead to signal degradation and unreliable operation of the DMX network.
Four-pin XLR connectors are used in a variety of applications. They are the standard connector such as systems made by ClearCom and Telex. Two pins are
An audio engineer helps to produce a recording or a live performance and adjusting sound sources using equalization and audio effects, mixing and reinforcement of sound. Audio engineers work on the "...technical aspect of recording—the placing of microphones, pre-amp knobs, the setting of levels. The physical recording of any project is done by an engineer... the nuts and bolts." It's a creative hobby and profession where musical instruments and technology are used to produce sound for film, television and video games. Audio engineers set up, sound check and do live sound mixing using a mixing console and a sound reinforcement system for music concerts, sports games and corporate events. Alternatively, audio engineer can refer to a scientist or professional engineer who holds an engineering degree and who designs and builds audio or musical technology working under terms such as acoustical engineering, electronic/electrical engineering or signal processing. Research and development audio engineers invent new technologies and techniques, to enhance the process and art of audio engineering.
They might design acoustical simulations of rooms, shape algorithms for audio signal processing, specify the requirements for public address systems, carry out research on audible sound for video game console manufacturers, other advanced fields of audio engineering. They might be referred to as acoustic engineers. Audio engineers working in research and development may come from backgrounds such as acoustics, computer science, broadcast engineering, acoustical engineering, electrical engineering and electronics. Audio engineering courses at university or college fall into two rough categories: training in the creative use of audio as a sound engineer, training in science or engineering topics, which allows students to apply these concepts while pursuing a career developing audio technologies. Audio training courses give you a good knowledge of technologies and their application to recording studio and sound reinforcement systems, but do not have sufficient mathematical and scientific content to allow you to get a job in research and development in the audio and acoustic industry.
Audio engineers in research and development possess a bachelor's degree, master's degree or higher qualification in acoustics, computer science or another engineering discipline. They might work in acoustic consultancy. Alternatively they might work in audio companies, or other industries that need audio expertise, or carry out research in a university; some positions, such as faculty require a Doctor of Philosophy. In Germany a Toningenieur is an audio engineer who designs and repairs audio systems; the listed subdisciplines are based on PACS coding used by the Acoustical Society of America with some revision. Audio engineers develop audio signal processing algorithms to allow the electronic manipulation of audio signals; these can be processed at the heart of much audio production such as reverberation, Auto-Tune or perceptual coding. Alternatively, the algorithms might carry out echo cancellation on Skype, or identify and categorize audio tracks through Music Information Retrieval. Architectural acoustics is the engineering of achieving a good sound within a room.
For audio engineers, architectural acoustics can be about achieving good speech intelligibility in a stadium or enhancing the quality of music in a theatre. Architectural Acoustic design is done by acoustic consultants. Electroacoustics is concerned with the design of headphones, loudspeakers, sound reproduction systems and recording technologies. Examples of electroacoustic design include portable electronic devices, sound systems in architectural acoustics, surround sound and wave field synthesis in movie theater and vehicle audio. Musical acoustics is concerned with describing the science of music. In audio engineering, this includes the design of electronic instruments such as synthesizers. Psychoacoustics is the scientific study of. At the heart of audio engineering are listeners who are the final arbitrator as to whether an audio design is successful, such as whether a binaural recording sounds immersive; the production, computer processing and perception of speech is an important part of audio engineering.
Ensuring speech is transmitted intelligibly and with high quality. A variety of terms are used to describe audio engineers who install or operate sound recording, sound reinforcement, or sound broadcasting equipment, including large and small format consoles. Terms such as "audio technician," "sound technician," "audio engineer," "audio technologist," "recording engineer," "sound mixer" and "sound engineer" can be ambiguous; such terms can refer to a person working in music production.
Koninklijke Philips N. V. is a Dutch multinational technology company headquartered in Amsterdam, one of the largest electronics companies in the world focused in the area of healthcare and lighting. It was founded in Eindhoven in 1891 by Gerard Philips and his father Frederik, with their first products being light bulbs, it was once one of the largest electronic conglomerates in the world and employs around 74,000 people across 100 countries. The company gained its royal honorary title in 1998 and dropped the "Electronics" in its name in 2013. Philips is organized into two main divisions: Philips Consumer Health and Well-being and Philips Professional Healthcare; the lighting division was spun off as a separate company, Signify N. V.. The company started making electric shavers in 1939 under the Philishave brand, post-war they developed the Compact Cassette format and co-developed the Compact Disc format with Sony, as well as numerous other technologies; as of 2012, Philips was the largest manufacturer of lighting in the world as measured by applicable revenues.
Philips has a primary listing on the Euronext Amsterdam stock exchange and is a component of the Euro Stoxx 50 stock market index. It has a secondary listing on the New York Stock Exchange. Acquisitions include that of Magnavox, they have had a sports club since 1913 called PSV Eindhoven. The Philips Company was founded by Gerard Philips and his father Frederik Philips. Frederik, a banker based in Zaltbommel, financed the purchase and setup of an empty factory building in Eindhoven, where the company started the production of carbon-filament lamps and other electro-technical products in 1892; this first factory is used as a museum. In 1895, after a difficult first few years and near bankruptcy, the Philipses brought in Anton, Gerard's younger brother by sixteen years. Though he had earned a degree in engineering, Anton started work as a sales representative. With Anton's arrival, the family business began to expand resulting in the founding of Philips Metaalgloeilampfabriek N. V. in Eindhoven in 1908, followed in 1912, by the foundation of Philips Gloeilampenfabrieken N.
V.. After Gerard and Anton Philips changed their family business by founding the Philips corporation, they laid the foundations for the electronics multinational. In the 1920s, the company started to manufacture other products, such as vacuum tubes. In 1939, they introduced the Philishave; the "Chapel" is a radio with built-in loudspeaker, designed during the early 1930s. On 11 March 1927, Philips went on the air with shortwave radio station PCJJ, joined in 1929 by sister station PHOHI. PHOHI broadcast in Dutch to the Dutch East Indies while PCJJ broadcast in English and German to the rest of the world; the international program on Sundays commenced in 1928, with host Eddie Startz hosting the Happy Station show, which became the world's longest-running shortwave program. Broadcasts from the Netherlands were interrupted by the German invasion in May 1940; the Germans commandeered the transmitters in Huizen to use for pro-Nazi broadcasts, some originating from Germany, others concerts from Dutch broadcasters under German control.
Philips Radio was absorbed shortly after liberation when its two shortwave stations were nationalised in 1947 and renamed Radio Netherlands Worldwide, the Dutch International Service. Some PCJ programs, such as Happy Station, continued on the new station. Philips was instrumental in the revival of the Stirling engine when, in the early 1930s, the management decided that offering a low-power portable generator would assist in expanding sales of its radios into parts of the world where mains electricity was unavailable and the supply of batteries uncertain. Engineers at the company's research lab carried out a systematic comparison of various power sources and determined that the forgotten Stirling engine would be most suitable, citing its quiet operation and ability to run on a variety of heat sources, they were aware that, unlike steam and internal combustion engines no serious development work had been carried out on the Stirling engine for many years and asserted that modern materials and know-how should enable great improvements.
Encouraged by their first experimental engine, which produced 16 W of shaft power from a bore and stroke of 30 mm × 25 mm, various development models were produced in a program which continued throughout World War II. By the late 1940s, the'Type 10' was ready to be handed over to Philips's subsidiary Johan de Witt in Dordrecht to be produced and incorporated into a generator set as planned; the result, rated at 180/200 W electrical output from a bore and stroke of 55 mm × 27 mm, was designated MP1002CA. Production of an initial batch of 250 began in 1951, but it became clear that they could not be made at a competitive price, besides with the advent of transistor radios with their much lower power requirements meant that the original rationale for the set was disappearing. 150 of these sets were produced. In parallel with the generator set, Philips developed experimental Stirling engines for a wide variety of applic
Composite video is an analog video transmission that carries standard definition video at 480i or 576i resolution as a single channel. Video information is encoded on one channel, unlike the higher-quality S-video and the higher-quality component video. In all of these video formats, audio is carried on a separate connection. Composite video is known by the initials CVBS for composite video baseband signal or color, video and sync, or is referred to as SD video for the standard-definition television signal it conveys. There are three dominant variants of composite video: NTSC, PAL, SECAM. A composite video signal combines, on one wire, the video information required to recreate a color picture, as well as line and frame synchronization pulses; the color video signal is a linear combination of the luminance of the picture and a modulated subcarrier which carries the chrominance or color information, a combination of hue and saturation. Details of the combining process vary between the PAL and SECAM systems.
The frequency spectrum of the modulated color signal overlaps that of the baseband signal, separation relies on the fact that frequency components of the baseband signal tend to be near harmonics of the horizontal scanning rate, while the color carrier is selected to be an odd multiple of half the horizontal scanning rate. In other words, the combination of luma and chroma is indeed a frequency-division technique, but it is much more complex than typical frequency-division multiplexing systems like the one used to multiplex analog radio stations on both the AM and FM bands. A gated and filtered signal derived from the color subcarrier, called the burst or colorburst, is added to the horizontal blanking interval of each line as a synchronizing signal and amplitude reference for the chrominance signals; the burst signal is inverted in phase from the reference subcarrier. Composite video can be directed to any broadcast channel by modulating the proper RF carrier wave with it. Most home analog video equipment record a signal in composite format: LaserDiscs store a true composite signal, while consumer videotape formats and lesser commercial and industrial tape formats use modified composite signals.
On playback, these devices give the user the option to output the baseband signal or to modulate it onto a VHF or UHF frequency compatible with a TV tuner. The professional television production uncompressed digital video videocassette format known as D-2 directly records and reproduces standard NTSC composite video signals, using PCM encoding of the analog signal on the magnetic tape. In home applications, the composite video signal is connected using an RCA connector yellow, it is accompanied with red and white connectors for right and left audio channels respectively. BNC connectors and higher quality coaxial cable are used in professional television studios and post-production applications. BNC connectors were used for composite video connections on early home VCRs accompanied by either phono connectors or a 5-pin DIN connector for audio; the BNC connector, in turn post dated the PL-259 connector which featured on first generation VCRs. In Europe, SCART connections are used instead of RCA jacks, so where available, RGB is used instead of composite video with computers, video game consoles, DVD players.
Video cables are low in capacitance. Typical values run from 52 pF/m for an HDPE-foamed dielectric precision video cable to 69 pF/m for a solid PE dielectric cable; some devices that connect to a TV, such as VCRs, older video game consoles and home computers of the 1980s, output a composite signal. This may be converted to RF with an external box known as an RF modulator that generates the proper carrier. Sometimes this modulator was built into the product and sometimes it was an external unit powered by the computer or with an independent power supply. In the United States, using an external RF modulator frees the manufacturer from obtaining FCC approval for each variation of a device. Through the early 1980s, electronics that output a television channel signal were required to meet the same shielding requirements as broadcast television equipment, thus forcing manufacturers such as Apple to omit an RF modulator, Texas Instruments to have their RF modulator as an external unit, which they had certified by the FCC without mentioning they were planning to sell it with a computer.
In Europe, while most countries used the same broadcast standard, there were different modulation standards, using an external modulator allowed manufacturers to make a single product and sell it to different countries by changing the modulator. Video game consoles on the other hand were less of an issue with FCC approval because the circuitry was inexpensive enough to allow for channel 3/4 outputs. Modern day devices with analog outputs have omitted channel 3 and 4 outputs in favor of composite and S-video outputs (or have switched to using HDMI or other di
DTS (sound system)
DTS, Inc. is an American company that makes multichannel audio technologies for film and video. Based in Calabasas, the company introduced its DTS technology in 1993 as a higher-quality competitor to Dolby Laboratories, incorporating DTS in the film Jurassic Park; the DTS product is used in surround sound formats for both commercial/theatrical and consumer-grade applications. It was known as The Digital Experience until 1995. DTS licenses its technologies to consumer electronics manufacturers; the DTS brand was bought by Tessera in December 2016 Tessera changed its name to Xperi. DTS was founded by an audio engineer and Caltech graduate. Beard, speaking to a friend of a friend, was able to get in touch with Steven Spielberg to audition a remastering of Spielberg's film Close Encounters of the Third Kind mixed in DTS. Spielberg selected DTS sound for his next film, Jurassic Park and with the backing of Universal Pictures and its then-parent Matsushita Electric, over 1,000 theatres in the United States adopted the DTS system.
Work on the new audio format started in 1991, four years after Dolby Laboratories started work on its new codec, Dolby Digital. The basic and most common version of the format is a 5.1-channel system, similar to a Dolby Digital setup, which encodes the audio as five primary channels plus a special LFE channel for the subwoofer. Encoders and decoders support numerous channel combinations, stereo, four-channel, four-channel+LFE soundtracks have been released commercially on DVD, CD, Laserdisc. Other, newer DTS variants are currently available, including versions that support up to seven primary audio channels plus one LFE channel; these variants are based on DTS's core-and-extension philosophy, in which a core DTS data stream is augmented with an extension stream which includes the additional data necessary for the new variant in use. The core stream can be decoded by any DTS decoder if it does not understand the new variant. A decoder which does understand the new variant decodes the core stream, modifies it according to the instructions contained in the extension stream.
This method allows backward compatibility. DTS's main competitors in multichannel theatrical audio are Dolby Digital and SDDS, although only Dolby Digital and DTS are used on DVDs and implemented in home theater hardware. One of the DTS Inc.'s initial investors was film director Steven Spielberg, who felt that theatrical sound formats up until the company's founding were no longer state of the art, as a result were no longer optimal for use on projects where quality sound reproduction was of the utmost importance. Spielberg debuted the format with his 1993 production of Jurassic Park, which came less than a full year after the official theatrical debut of Dolby Digital. In addition, Jurassic Park became the first home video release to contain DTS sound when it was released on LaserDisc in January 1997, two years after the first Dolby Digital home video release, which debuted in January 1995. In 2008, the cinema division was divested to form DTS Digital Cinema. In 2009 DTS Digital Cinema was purchased by Beaufort International Group Plc. and became known as Datasat Digital Entertainment.
In 2012, DTS acquired the business of SRS Labs, a psychoacoustic 3D audio processing technology, including over 1,000 audio patents and trademarks. In 2014, DTS acquired Manzanita Systems, a provider of MPEG software solutions for digital television, VOD, digital ad insertion. Phorus, a subsidiary of DTS, Inc. is a Los Angeles based technology group dedicated to wireless audio solutions for connected devices. On September 2, 2015, iBiquity announced that it was being purchased by DTS for US$172 million, uniting iBiquity's HD Radio digital radio broadcast technology with DTS' digital audio surround sound systems. In theatrical use, a proprietary 24-bit time code is optically imaged onto the film. An LED reader scans the timecode data from the film and sends it to the DTS processor, using the time code to synchronize the projected image with the DTS soundtrack audio; the multi-channel DTS audio is recorded in compressed form on standard CD-ROM media at a bitrate of 882 kbit/s. The audio compression used in the theatrical DTS system is the APT-X100 system.
Unlike the home version of DTS or any version of Dolby Digital, the APT-X100 system is fixed at a 4:1 compression ratio. Data reduction is accomplished via sub-band coding with linear adaptive quantization; the theatrical DTS processor acts as a transport mechanism, as it reads the audio discs. When the DTS format was launched, it used one or two discs with units holding three discs, thus allowing a single DTS processor to handle two-disc film soundtracks along with a third disc for theatrical trailers; the DTS time code on the 35mm print identifies the film title, matched to the individual DTS CD-ROMs, guaranteeing that the film cannot be played with the wrong disc. Each DTS CD-ROM contains a DOS program that the processor uses to play back the soundtrack, allowing system improvements or bug fixes to be added easily. Unlike Dolby Digital and SDDS, or the home version of DTS, the theatrical DTS system only carries 5 discrete channels on the CD-ROMs. The.1 LFE subwoofer track is mixed into the discrete surround channels on the disc and recovered via low-pass filters in the theater.
On the consumer level, DTS is the oft-used shorthand for the DTS Coherent Acoustics codec, transportable through S/PDIF and part of the LaserDisc, DVD, Blu-ray specif