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Digital Audio Tape

150px
A 90-minute DAT cartridge, size compared to a AAA (LR03) battery.
Media type	Magnetic tape
Capacity	120 minutes
Read mechanism	Rotating head
Write mechanism	Rotating head, helical scan
Developed by	Sony
Usage	Audio storage

Digital Audio Tape (DAT or R-DAT) is a signal recording and playback medium developed by Sony and introduced in 1987.^[1] In appearance it is similar to a compact audio cassette, using 4 mm magnetic tape enclosed in a protective shell, but is roughly half the size at 73 mm × 54 mm × 10.5 mm. As the name suggests, the recording is digital rather than analog. DAT has the ability to record at higher, equal or lower sampling rates than a CD (48, 44.1 or 32 kHz sampling rate respectively) at 16 bits quantization. If a digital source is copied then the DAT will produce an exact clone, unlike other digital media such as Digital Compact Cassette or non-Hi-MD MiniDisc, both of which use a lossy data reduction system.

Like most formats of videocassette, a DAT cassette may only be recorded and played in one direction, unlike an analog compact audio cassette.

Although intended as a replacement for audio cassettes, the format was never widely adopted by consumers because of issues of expense and concerns from the music industry about unauthorized digital quality copies. The format saw moderate success in professional markets and as a computer storage medium. As Sony has ceased production of new recorders, it will become more difficult to play archived recordings in this format unless they are copied to other formats or hard drives.

History[link]

Development[link]

The technology of DAT is closely based on that of video recorders, using a rotating head and helical scan to record data. This prevents DATs from being physically edited in the cut-and-splice manner of analog tapes, or open-reel digital tapes like ProDigi or DASH.

The DAT standard allows for four sampling modes: 32 kHz at 12 bits, and 32 kHz, 44.1 kHz or 48 kHz at 16 bits. Certain recorders operate outside the specification, allowing recording at 96 kHz and 24 bits (HHS). Some machines aimed at the domestic^[where?] market did not operate at 44.1 kHz when recording from analog sources. Since each recording standard uses the same tape, the quality of the sampling has a direct relation to the duration of the recording – 32 kHz at 12 bits will allow six hours of recording onto a three hour tape while HHS will only give 90 minutes from the same tape. Included in the signal data are subcodes to indicate the start and end of tracks or to skip a section entirely; this allows for indexing and fast seeking. Two-channel stereo recording is supported under all sampling rates and bit depths, but the R-DAT standard does support 4-channel recording at 32 kHz.

DAT "tapes" are between 15 and 180 minutes in length, a 120-minute tape being 60 meters in length. DAT "tapes" longer than 60 meters tend to be problematic in DAT recorders due to the thinner media. DAT machines running at 48 kHz and 44.1 kHz sample rates transport the tape at 8.15 mm/s. DAT machines running at 32 kHz sample rate transport the tape at 4.075 mm/s.

Predecessor formats[link]

DAT was not the first digital audio tape; pulse-code modulation (PCM) was used in Japan by Denon in 1972 for the mastering and production of analogue phonograph records, using a 2-inch Quadruplex-format videotape recorder for its transport, but this was not developed into a consumer product. Denon's development dated from its work with Japan's NHK Broadcasting; NHK developed the first high-fidelity PCM audio recorder in the late 1960s. Denon continued development of their PCM recorders that used professional video machines as the storage medium, eventually building 8-track units used for, among other productions, a series of jazz records made in New York in the late 1970s.

In 1976, another digital audio tape format was developed by Soundstream, using 1 inch (25.4 mm) wide reel-to-reel tape loaded on an instrumentation recorder manufactured by Honeywell acting as a transport, which in turn was connected to outboard digital audio encoding and decoding hardware of Soundstream's own design. Soundstream's format was improved through several prototypes and when it was developed to 50kHz sampling rate at 16 bits, it was deemed good enough for professional classical recording by the company's first client, Telarc Records of Cleveland, Ohio. Telarc's April, 1978 recording of the Holst Suites for Band by Fred Fennell and the Cleveland Wind Ensemble was a landmark release, and ushered in digital recording for America's classical music labels. Soundstream's system was also used by RCA.

Starting in 1978, 3M introduced its own line and format of digital audio tape recorders for use in a recording studio. One of the first prototypes of 3M's system was installed in the studios of Sound 80 in Minneapolis, Minnesota. This system was used in June 1978 to record Aaron Copland's "Appalachian Spring" by the St. Paul Chamber Orchestra conducted by Dennis Russell Davies. That record was the first Grammy-winning digital recording. The production version of the 3M Digital Mastering System was used in 1979 to record the first all-digital rock album, Ry Cooder's "Bop Till You Drop," made at Warner Brothers Studio in California.

The first consumer-oriented PCM format used consumer video tape formats (Beta and VHS) as the storage medium. These systems used the EIAJ digital format, which sampled at 44.056kHz at 14 bits. The Sony PCM-F1 system debuted in 1981, and Sony from the start offered the option of 16-bit wordlength. Other systems were marketed by Akai, JVC, Nakamichi and others. Panasonic, via its Technics division, briefly sold a digital recorder that combined a EIAJ digital adapter with a VHS video transport, the SV-P100. These machines were marketed by consumer electronics companies to consumers, but they were very pricey compared to cassette or even reel-to-reel decks of the time. They did catch on with the more budget conscious professional recordists, and some boutique-label professional releases were recorded using these machines.^[2]

Starting in the early 1980s, professional systems using a PCM adaptor were also common as mastering formats. These systems digitized an analog audio signal and then encoded the resulting digital stream into an analog video signal so that a conventional VCR could be used as a storage medium.

One of the most significant examples of a PCM adaptor-based system was the Sony PCM-1600 digital audio mastering system, introduced in 1978. The PCM-1600 used a U-Matic-format VCR for its transport, connected to external digital audio processing hardware. It (and its later versions such as the PCM-1610 and 1630) was widely used for the production and mastering of some of the first Digital Audio CDs in the early 1980s. Once CD's were commercially introduced in 1983, tapes recorded on the PCM-1600 were sent to the CD pressing plants to be used to make the glass master disc for CD replication.

Other examples include dbx, Inc.'s Model 700 system, which, similar to modern Super Audio CDs, used a high sample-rate delta-sigma modulation rather than PCM; Decca's 1970s PCM system,^[3] which used a videotape recorder manufactured by IVC for a transport; and Mitsubishi's X-80 digital recorder, a 6.4 mm (¼ in) open reel digital mastering format that used a very unusual sampling rate of 50.4 kHz.

For high-quality studio recording, all of these formats were effectively made obsolete in the early 1980s by two competing reel-to-reel formats with stationary heads: Sony's DASH format and Mitsubishi's continuation of the X-80 recorder, which was improved upon to become the ProDigi format. (In fact, one of the first ProDigi-format recorders, the Mitsubishi X-86C, was playback-compatible with tapes recorded on an X-80.) Both of these formats remained popular as an analog alternative until the early 1990s, when hard disk recorders rendered them obsolete.

R-DAT and S-DAT (DCC)[link]

The DAT recorder mechanism was considerably more complex and expensive than an analogue cassette deck mechanism due to the rotary helical scan head, therefore Philips & Panasonic Corporation developed a rival digital tape recorder system with a stationary head based on the analogue compact cassette. The DCC was cheaper and simpler mechanically than DAT, but did not make perfect digital copies as it used a lossy compression technique called PASC. (Lossy compression was necessary to reduce the data rate to a level that a stationary head could cope with). DCC was never a competitor to DAT in recording studios because DAT was already established and as it was launched at the same time as Sony's Minidisc format (which has random access and editing features) it was not successful with consumers either. However, DCC proved that high quality digital recording could be achieved with a cheap simple mechanism using stationary heads.

Anti-DAT lobbying[link]

In the late 1980s, the Recording Industry Association of America (RIAA) unsuccessfully lobbied against the introduction of DAT devices into the U.S. Initially, the organization threatened legal action against any manufacturer attempting to sell DAT machines in the country. It later sought to impose restrictions on DAT recorders to prevent them from being used to copy LPs, CDs, and prerecorded cassettes. One of these efforts, the Digital Audio Recorder Copycode Act of 1987 (introduced by Sen. Al Gore and Rep. Waxman), instigated by CBS Records president Walter Yetnikoff, involved a technology called CopyCode and required DAT machines to include a chip to detect attempts to copy material recorded with a notch filter,^{[clarification needed]} meaning that copyrighted prerecorded music, whether analog or digital, would have distorted sound. A National Bureau of Standards study showed that not only were the effects plainly audible, but that it was not even effective at preventing copying.

This opposition by CBS softened after Sony, a DAT manufacturer, bought CBS Records in January 1988. By June 1989, an agreement was reached, and the only concession the RIAA would receive was a more practical recommendation from manufacturers to Congress that legislation be enacted to require that recorders have a Serial Copy Management System to prevent digital copying for more than a single generation.^[4] This requirement was enacted as part of the Audio Home Recording Act of 1992, which also imposed taxes on DAT recorders and blank media.

Uses of DAT[link]

Professional recording industry[link]

DAT was used professionally in the 1990s by the professional audio recording industry as part of an emerging all-digital production chain also including digital multi-track recorders and digital mixing consoles that was used to create a fully digital recording. In this configuration, it is possible for the audio to remain digital from the first AD converter after the mic preamp until it is in a CD player.

Amateur and home use[link]

DAT was envisaged by proponents as the successor format to analogue audio cassettes in the way that the compact disc was the successor to vinyl-based recordings; however, the technology was never as commercially popular as CD or cassette. DAT recorders remained relatively expensive, and commercial recordings were generally not made available on the format. However, DAT was, for a time, popular for making and trading recordings of live music (see bootleg recording), since available DAT recorders predated affordable CD recorders.

Computer data storage medium[link]

The format was designed for audio use, but through the ISO Digital Data Storage standard was adopted for general data storage, storing from 1.3 to 80 GB on a 60 to 180 meter tape depending on the standard and compression. It is a sequential-access medium and is commonly used for backups. Due to the higher requirements for capacity and integrity in data backups, a computer-grade DAT was introduced, called DDS (Digital Data Storage). Although functionally similar to audio DATs, only a few DDS and DAT drives (in particular, those manufactured by Archive for SGI workstations)^[5] are capable of reading the audio data from a DAT cassette. SGI DDS4 drives no longer have audio support; SGI removed the feature due to "lack of demand".^[6]

Future of DAT[link]

In November 2005, Sony announced that its remaining DAT machine models would be discontinued the following month.^[7] Sony has sold around 660,000 DAT products since its introduction in 1987.^{[citation needed]} However, the DAT format still finds regular use in film and television recording,^{[citation needed]} principally due to the support in some recorders for SMPTE time code synchronization. It is slowly being superseded by modern hard disk recording equipment which offers much more flexibility and storage. In 2004, Sony introduced the Hi-MD Walkman with the ability to record in linear PCM. Hi-MD has found some favor as a disc-based DAT alternative for field recordings and general portable playback.^{[citation needed]}

See also[link]

• ADAT
• Digital Audio Stationary Head
• Digital Data Storage (DDS)
• Magnetic storage
• Magnetic tape
• Magnetic tape sound recording
• PCM adaptor
• ProDigi

References[link]

v t e Sony Corporation Primary businesses Sony Corporation (electronics & holding of the Sony group) · Sony Music Entertainment (music) · Sony Pictures Entertainment (motion pictures and television) · Sony Computer Entertainment (video games) · Sony Financial Holdings (financial services; 60%) · Sony Digital Audio Disc Corporation Technologies and brands α · Betacam · Blu-ray · BRAVIA · CD · Cyber-shot · Dash · Dream Machine · DVD · Handycam · HDCAM/HDCAM-SR · LocationFree · Memory Stick · MiniDisc · MiniDV · mylo · Reader · S/PDIF · SDDS · SXRD · Sony Tablet · UMD · VAIO · Video8/Hi8/Digital8 · Walkman · Walkman Phones · XDCAM · Xplōd · HMZ-T1 Historical products AIBO · CV-2000 · DAT · Betamax · Sony CLIÉ · Discman · JumboTron · Lissa · Mavica · NEWS · Qualia · Rolly · TR-55 · Trinitron · U-matic · Watchman · WEGA Electronics Sony EMCS · Sony Electronics (subsidiary in the US) · Sony Creative Software · Sony Mobile Communications  · S-LCD (50% minus 1 share) · Sony Mobile Display · Sony Optiarc · Sharp Display Products (7%) · Aiwa (former) Sony Music Entertainment Sony/ATV Music Publishing (50%) · Columbia Records · Epic Records · RCA Records · Sony Music Nashville (Arista Nashville, BNA Records, Columbia Nashville, RCA Records Nashville) · Provident Label Group · Verity Gospel Music Group · Sony Music Latin · Sony Masterworks  · Legacy Recordings  · RED Distribution  · IODA  · Syco Music  · Syco TV  · Syco Film  · Sony Music Australia · Sony Music Japan  · Gracenote · Aniplex · A-1 Pictures Sony Pictures Entertainment Columbia TriStar Motion Picture Group (Columbia Pictures · Sony Pictures Classics · Screen Gems · TriStar Pictures · Triumph Films) · Sony Pictures Worldwide Acquisitions (Destination Films · Stage 6 Films · Affirm Films) · Sony Pictures Television Group (Adelaide Productions · Culver Entertainment · Embassy Row · 2waytraffic · Lean-M  · Gogglebox Entertainment · Victory Television · Silver River Productions · Starling · Huaso · Floresta · Teleset) Sony Pictures Home Entertainment · Sony Wonder · Sony Pictures Family Entertainment Group · Sony Pictures Digital (Sony Pictures Imageworks · Sony Pictures Animation · Sony Pictures Mobile) · Sony Pictures Studios · Sony Pictures Consumer Marketing (Sony Pictures Consumer Products · Sony Pictures Loot) U.S. networks Sony Movie Channel · GSN (40%), joint venture with DirecTV · FEARnet HD (joint venture with Comcast and Lionsgate) · 3net (joint venture with Discovery Communications and IMAX) International networks Sony Entertainment Television (Asia, South East Asia, India, Latin America, South Africa, Portugal, Russia, Spain, Baltic and United Kingdom) · AXN · AXN HD · AXN HD+1 · AXN Asia · AXN India · AXN Pakistan · AXN White · AXN Crime · AXN Black · AXN Mystery · AXN Sci Fi · AXN Spin · Sony Aath · Multi Screen Media · Animax · Animax Asia · Animax India · Animax Pakistan · Animax Korea · Animax Eastern Europe · BeTV · Sony Spin · SET One · SET Max · Sony SIX · Sony MIX · SET PIX · SAB TV · Men&Movies · Movies4Men Sony Computer Entertainment Sony Online Entertainment · PlayStation · PSP · PlayStation Vita · Cellius (49%) · Square Enix (8.25%) · Sony Imagesoft (defunct) Online distribution platforms Sony Entertainment Network (Music Unlimited · Video Unlimited · PlayStation Network) · FEARnet · The Minisode Network · Crackle Financial services Sony Financial Holdings · Sony Life Insurance · Sony Assurance · Sony Bank · Sony Bank Securities Other businesses So-net Entertainment · Sony Broadcast & Professional Research Laboratories · Sony Sendai Other assets Sony Corporation of America (umbrella company in the US) · Other subsidiaries Joint ventures Sony/ATV · FeliCa Networks · Vevo · Cellius (49%) · Sharp Display Products (7.04%) Key personnel Kazuo Hirai · Masaru Ibuka · Nobuyuki Idei · Yasuo Kuroki · Ken Kutaragi · Michael Lynton · Akio Morita · Norio Ohga · Amy Pascal · Howard Stringer  · Nicole Seligman Category ·  Commons ·  Wikinews

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Klaudia Wilde from the German WDR radio archive with a broadcast tape from 1990

The use of magnetic tape for sound recording originated around 1930. Magnetizable tape revolutionized both the radio broadcast and music recording industries. It did this by giving artists and producers the power to record and re-record audio with minimal loss in quality as well as edit and rearrange recordings with ease. The alternative recording technologies of the era, transcription discs and wire recorders, could not provide anywhere near this level of quality and functionality. Since some early refinements improved the fidelity of the reproduced sound, magnetic tape has been the highest quality analog sound recording medium available. However, as of the first decade of the 21st century, magnetic tape is largely being replaced by hard disk drives or memory cards for most sound recording purposes.

Prior to the development of magnetic tape, magnetic wire recorders had successfully demonstrated the concept of magnetic recording, but they never offered audio quality comparable to the recording and broadcast standards of the time. Some individuals and organizations developed innovative uses for magnetic wire recorders while others investigated variations of the technology. One particularly important variation was the application of an oxide powder to a long strip of paper. This German invention was the start of a long string of innovations that have led to present day magnetic tape recordings.

Origins[link]

Magnetic recording[link]

Magnetic recording was conceived of as early as 1877 by the American engineer Oberlin Smith and demonstrated in practice in 1898 by Danish engineer Valdemar Poulsen. Analog magnetic wire recording, and its successor, magnetic tape recording, involve the use of a magnetizable medium which moves with a constant speed past a recording head. An electrical signal, which is analogous to the sound that is to be recorded, is fed to the recording head, inducing a pattern of magnetization similar to the signal. A playback head can then pick up the changes in magnetic field from the tape and convert it into an electrical signal.

Early steel tape recorders[link]

Early tape recorders were created by replacing the steel wire of a wire recorder with a thin steel tape. The first of these modified wire recorders was the Blattnerphone, created in 1929 or 1930 by the Ludwig Blattner Picture Corporation.

In 1931, Clarence N. Hickman of Bell Labs completed a prototype steel tape recorder based telephone answering machine. The machine saw limited use because AT&T policy forbade its use on public telephone lines.

On Christmas Day 1932 the British Broadcasting Corporation first used a tape recorder for their broadcasts. The device used was a Marconi-Stille recorder, a huge tape machine which used steel razor tape 3 mm wide and 0.08 mm thick. In order to reproduce the higher audio frequencies it was necessary to run the tape at 1500 millimetres per second past the recording and reproducing heads. This meant that the length of tape required for a half-hour programme was nearly 3 kilometres and a full reel weighed 25 kg. For safety reasons these machines would only be operated in a locked room by remote control. Due to the tape's speed, springiness and razor-like sharp edges, if the tape broke while in operation, it could unspool, fly off and cause serious injury. Besides this, the methods of recording could lead to massive data loss and poor audio quality because of their nature.

By the mid 1930s, the C. Lorenz company in Germany had developed a steel tape recorder that was briefly popular with European telephone companies and German radio networks. In 1938, Begun left Germany and joined the Brush Development Company in the United States, where work continued but attracted little attention until the late 1940s when the company released the very first commercial tape recorder in 1946: the Soundmirror BK 401. Several other models were quickly released in the following years. Tapes were initially made of paper coated with black oxide. Minnesota Mining & Manufacturing Company (3M) replaced them by plastic tapes in 1948.^{[dubious – discuss][citation needed]}

German developments[link]

Magnetic tape recording as we know it today was developed in Germany during the 1930s at BASF (then part of the chemical giant IG Farben) and AEG in cooperation with the RRG. This was based on Fritz Pfleumer's 1928 invention of paper tape with oxide powder lacquered to it.

Engineers at AEG created the world's first practical magnetic tape recorder, the 'K1', and first demonstrated it in 1935. Eduard Schüller of AEG built the recorders and developed a ring shaped recording and playback head. It replaced the needle shaped head which tended to shred the tape. Friedrich Matthias of IG Farben/BASF developed the recording tape, including the oxide, the binder, and the backing material. Walter Weber, working for Hans Joachim von Braunmühl at the RRG, discovered the AC biasing technique, which radically improved sound quality.^[1]

During World War II, the Allies noticed that certain German officials were making radio broadcasts from multiple time zones almost simultaneously.^[1] Analysts such as Richard H. Ranger believed that the broadcasts had to be transcriptions, but their audio quality was indistinguishable from that of a live broadcast^[1] and their duration was far longer than was possible with 78 rpm discs. In the final stages of the war in Europe, the Allied capture of a number of German Magnetophon recorders from Radio Luxembourg aroused great interest. These recorders incorporated all of the key technological features of modern analog magnetic recording and were the basis for future developments in the field.

Commercialization[link]

American developments[link]

Development of magnetic tape recorders in the late 1940s and early 1950s is associated with the Brush Development Company and its licensee, Ampex. The equally important development of the magnetic tape media itself was led by Minnesota Mining and Manufacturing (3M) corporation.

American audio engineer John T. Mullin and entertainer Bing Crosby were key players in the commercial development of magnetic tape. Mullin served in the U.S. Army Signal Corps and was posted to Paris in the final months of WWII. His unit was assigned to find out everything they could about German radio and electronics, including the investigation of claims that the Germans had been experimenting with high-energy directed radio beams as a means of disabling the electrical systems of aircraft. Mullin's unit soon amassed a collection of hundreds of low-quality magnetic dictating machines, but it was a chance visit to a studio at Bad Nauheim near Frankfurt while investigating radio beam rumours, that yielded the real prize.

Mullin was given two suitcase-sized AEG 'Magnetophon' high-fidelity recorders and fifty reels of recording tape. He had them shipped home^[1] and over the next two years he worked on the machines constantly, modifying them and improving their performance. His major aim was to interest Hollywood studios in using magnetic tape for movie soundtrack recording.

Mullin gave two public demonstrations of his machines, and they caused a sensation among American audio professionals; many listeners literally could not believe that what they were hearing was not a live performance. By luck, Mullin's second demonstration was held at MGM studios in Hollywood and in the audience that day was Bing Crosby's technical director, Murdo Mackenzie. He arranged for Mullin to meet Crosby and in June 1947 he gave Crosby a private demonstration of his magnetic tape recorders.^[1]

Bing Crosby's influence[link]

Bing Crosby, a top movie and singing star, was stunned by the amazing sound quality and instantly saw the huge commercial potential of the new machines. Live music was the standard for American radio at the time and the major radio networks didn't permit the use of disc recording in many programs because of their comparatively poor sound quality. Crosby disliked the regimentation of live broadcasts 39 weeks a year,^[1] preferring the recording studio's relaxed atmosphere and ability to retain the best parts of a performance. He had asked NBC to let him pre-record his 1944-45 series on transcription discs, but the network refused, so Crosby had withdrawn from live radio for a year. ABC agreed to let him use transcription discs for the 1946-47 season, but listeners complained about the sound quality.^[1]

Mullin's tape recorder came along at precisely the right moment. Crosby realised that the new technology would enable him to pre-record his radio show with a sound quality that equalled live broadcasts, and that these tapes could be replayed many times with no appreciable loss of quality. Mullin was asked to tape one show as a test and was immediately hired as Crosby's chief engineer to pre-record the rest of the series.

Crosby's season premier on 1 October 1947 was the first magnetic tape broadcast in America.^[1] He became the first major American music star to use tape to pre-record radio broadcasts, and the first to master commercial recordings on tape. The taped Crosby radio shows were painstakingly edited through tape-splicing to give them a pace and flow that was wholly unprecedented in radio. Mullin even claims to have been the first to use "canned laughter"; at the insistence of Crosby's head writer, Bill Morrow, he inserted a segment of raucous laughter from an earlier show into a joke in a later show that hadn't worked well. Tape's high audio quality caused other radio performers to demand the ability to prerecord their broadcasts, forcing an end to the recording ban.^[1]

Keen to make use of the new recorders as soon as possible, Crosby invested $50,000 of his own money into the Californian electronics company Ampex, and the tiny six-man concern (headed by Alexander M. Poniatoff, whose initials became part of the company name) soon became the world leader in the development of tape recording, revolutionising radio and recording with its famous Model 200 tape deck, issued in 1948 and developed directly from Mullin's modified Magnetophones.

Standardized products[link]

Working with Mullin, Ampex rapidly developed two-track stereo and then three-track recorders.

The typical professional audio tape recorder of the early 1950s used ¼" wide tape on 10½" reels, with a capacity of 2400 feet (730 metres). Typical speeds were initially 15 in/s (38.1 cm/s) yielding 30 minutes' recording time on a 2400 ft (730 m) reel. 30 in/s (76.2 cm/s) was used for the highest quality work. Domestic and portable recorders used seven, five or even three inch reels (or spools). Early professional machines used single sided spools but double sided spools soon became popular (particularly for domestic use). Tape spools were usually made from transparent plastic but metal spools were also used.

Standard tape speeds varied by factors of two — 15 and 30 in/s were used for professional audio recording; 7½ in/s (19 cm/s) for home audiophile prerecorded tapes; 7½ and 3¾ in/s (19 and 9.5 cm/s) for audiophile and consumer recordings (typically on 7 in or 18 cm reels). 1⅞ in/s (4.76 cm/s) and occasionally even 15/16 in/s (2.38 cm/s) were used for voice, dictation, and applications where very long recording times were needed, such as logging police and fire department calls.

The 8-Track tape standard, promoted by Bill Lear in the early 1960s, popularized consumer audio playback in automobiles. Eventually, this standard was replaced by the smaller and more reliable Compact Cassette.

Philips' development of the Compact Cassette in 1963 and Sony's development of the Walkman in 1979 ^[2] led to widespread consumer use of magnetic audio tape. In 1990, the Compact Cassette was the dominant format in mass-market recorded music.^[3] The development of Dolby noise reduction technology in the 1960s brought audiophile quality recording to the Compact Cassette also contributing to its popularity.

Innovative uses[link]

Magnetic tape brought about sweeping changes in both radio and the recording industry. Sound could be recorded, erased and re-recorded on the same tape many times, sounds could be duplicated from tape to tape with only minor loss of quality, and recordings could now be very precisely edited by physically cutting the tape and rejoining it.

Within a few years of the introduction of the first commercial tape recorder, the Ampex 200 model, launched in 1948, American musician-inventor Les Paul had invented the first multitrack tape recorder, bringing about another technical revolution in the recording industry. Tape made possible the first sound recordings totally created by electronic means, opening the way for the bold sonic experiments of the Musique Concrète school and avant garde composers like Karlheinz Stockhausen, which in turn led to the innovative pop music studio recordings of artists such as Frank Zappa, The Beatles and The Beach Boys.

Tape enabled the radio industry for the first time to pre-record many sections of program content such as advertising, which formerly had to be presented live, and it also enabled the creation and duplication of complex, high-fidelity, long-duration recordings of entire programs. It also, for the first time, allowed broadcasters, regulators and other interested parties to undertake comprehensive logging of radio broadcasts for legislative and commercial purposes, leading to the growth of the modern media monitoring industry.

Innovations like multitrack recording and tape echo enabled radio programs and advertisements to be pre-produced to a level of complexity and sophistication that was previously unattainable and tape also led to significant changes to the pacing of program content, thanks to the introduction of the endless-loop tape cartridge.

See also[link]

• Analog recording - Other analog recording methods.
• Audio format - General list of audio recording formats, including magnetic tape.
• Audio tape length and thickness - Details of different audio tape formats.
• Digital audio –History of digital audio use in commercial recording
• History of sound recording ––Magnetic recording - Magnetic tape in the context of the history of sound recording.
• Tape recorder - Details regarding the workings of the recording machines.
• Magnetic recording -General description of the process.
• Multitrack recording - Advanced usage of sophisticated tape recorders.
• Preservation of magnetic audiotape
• Reel-to-reel audio tape recording - Details of using old style recorders.
• Sound recording and reproduction#Magnetic tape - Magnetic tape in the context of the history of sound recording.
• Tape recorder -The mechanical device that actual performs the recording and playback, to and from magnetic tape.
• Sound follower - For film

References[link]

External links[link]

• A timeline of developments in magnetic recording.
• A History of Magnetic Recording BBC/H2G2
• A Selected History of Magnetic Recording
• Walter Weber's Technical Innovation at the Reichs-Rundfunk-Gesellschaft
• Timeline from U of San Diego's Archive
• History of Recording Technology (WayBack Machine)
• History of Magnetic Tape (WayBack Machine)
• Description of the recording process with diagrams. pg. 2, pg. 3, pg. 4, pg. 5.

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A sound wave, in gray, represented digitally, in red (after quantization and zero-order hold).

Digital audio is sound reproduction using pulse-code modulation and digital signals. Digital audio systems include analog-to-digital conversion (ADC), digital-to-analog conversion (DAC), digital storage, processing and transmission components. A primary benefit of digital audio is in its convenience of storage, transmission and retrieval.

Overview of digital audio[link]

Sampling and 4-bit quantization of an analog signal (red) using Pulse-code modulation

Digital audio is useful in the recording, manipulation, mass-production, and distribution of sound. Modern distribution of music across the Internet via on-line stores depends on digital recording and digital compression algorithms. Distribution of audio as data files rather than as physical objects has significantly reduced the cost of distribution.

In an analog audio system, sounds begin as physical waveforms in the air, are transformed into an electrical representation of the waveform, via a transducer (for example, a microphone), and are stored or transmitted. To be re-created into sound, the process is reversed, through amplification and then conversion back into physical waveforms via a loudspeaker. Although its nature may change, analog audio's fundamental wave-like characteristics remain the same during its storage, transformation, duplication, and amplification.

Analog audio signals are susceptible to noise and distortion, unavoidable due to the innate characteristics of electronic circuits and associated devices. In the case of purely analog recording and reproduction, numerous opportunities for the introduction of noise and distortion exist throughout the entire process. When audio is digitized, distortion and noise are introduced only by the stages that precede conversion to digital format, and by the stages that follow conversion back to analog.

The digital audio chain begins when an analog audio signal is first sampled, and then (for pulse-code modulation, the usual form of digital audio) it is converted into binary signals—‘on/off’ pulses—which are stored as binary electronic, magnetic, or optical signals, rather than as continuous time, continuous level electronic or electromechanical signals. This signal may then be further encoded to allow correction of any errors that might occur in the storage or transmission of the signal, however this encoding is for error correction, and is not strictly part of the digital audio process. This "channel coding" is essential to the ability of broadcast or recorded digital system to avoid loss of bit accuracy. The discrete time and level of the binary signal allow a decoder to recreate the analog signal upon replay. An example of a channel code is Eight to Fourteen Bit Modulation as used in the audio Compact Disc (CD).

Conversion process[link]

The lifecycle of sound from its source, through an ADC, digital processing, a DAC, and finally as sound again.

A digital audio system starts with an ADC that converts an analog signal to a digital signal.^{[note 1]} The ADC runs at a sampling rate and converts at a known bit resolution. For example, CD audio has a sampling rate of 44.1 kHz (44,100 samples per second) and 16-bit resolution for each channel. For stereo there are two channels: 'left' and 'right'. If the analog signal is not already bandlimited then an anti-aliasing filter is necessary before conversion, to prevent aliasing in the digital signal. (Aliasing occurs when frequencies above the Nyquist frequency have not been band limited, and instead appear as audible artifacts in the lower frequencies).

The digital audio signal may be stored or transmitted. Digital audio storage can be on a CD, a digital audio player, a hard drive, USB flash drive, CompactFlash, or any other digital data storage device. The digital signal may then be altered in a process which is called digital signal processing where it may be filtered or have effects applied. Audio data compression techniques — such as MP3, Advanced Audio Coding, Ogg Vorbis, or FLAC — are commonly employed to reduce the file size. Digital audio can be streamed to other devices.

The last step is for digital audio to be converted back to an analog signal with a DAC. Like ADCs, DACs run at a specific sampling rate and bit resolution but through the processes of oversampling, upsampling, and downsampling, this sampling rate may not be the same as the initial sampling rate.

History of digital audio use in commercial recording[link]

Pulse-code modulation was invented by British scientist Alec Reeves in 1937^[1] 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 (a.k.a. Denon) in the 1960s. The first commercial digital recordings were released in 1971.^[2]

The BBC also began experimenting with digital audio in the 1960s. By the early 1970s they had developed a 2-channel recorder and in 1972 they deployed a digital audio transmission system linking their broadcast center to their remote transmitters.^[2]

The first 16-bit PCM recording in the United States was made by Thomas Stockham at the Santa Fe Opera in 1976 on a Soundstream recorder. In 1978, an improved version of the Soundstream system was used by Telarc to produce several classical recordings. At the same time 3M was well along in development of their digital multitrack recorder based on BBC technology. The first all-digital album recorded on this machine was Ry Cooder's "Bop 'Til You Drop" which was released in 1979. In a crash program started in 1978, British record label Decca developed their own 2-track digital audio recorders. Decca released the first European digital recording in 1979.^[2]

Helped along by introduction of popular digital multitrack recorders from Sony and Mitsubishi in the early 1980s, digital recording was soon embraced by the major record companies. With the introduction of the CD by Sony and Philips in 1982, digital audio was embraced by consumers as well.^[2]

Digital audio technologies[link]

Digital audio broadcasting

• Digital Audio Broadcasting (DAB)
• HD Radio
• Digital Radio Mondiale (DRM)
• In-band on-channel (IBOC)

Storage technologies

• Digital audio player
• Digital Audio Tape (DAT)
• Compact Disc (CD)
• Hard disk recorder
• DVD Audio
• MiniDisc
• Super Audio CD
• Various audio file formats

Digital audio interfaces[link]

Audio-specific interfaces include:

• AC'97 (Audio Codec 1997) interface between Integrated circuits on PC motherboards
• Intel High Definition Audio A modern replacement for AC'97
• ADAT interface
• AES3 interface with XLR connectors
• AES47, Professional AES3-style digital audio over Asynchronous Transfer Mode networks
• I²S (Inter-IC sound) interface between Integrated circuits in consumer electronics
• MADI Multichannel Audio Digital Interface
• MIDI low-bandwidth interconnect for carrying instrument data; cannot carry sound but can carry digital sample data in non-realtime
• S/PDIF, either over coaxial cable or TOSLINK
• TDIF, TASCAM proprietary format with D-sub cable
• A2DP via Bluetooth

Naturally, any digital bus (e.g., USB, FireWire, and PCI) can carry digital audio. Also, several interfaces are engineered to carry digital video and audio together, including HDMI and DisplayPort.

In professional architectural or installation applications, many digital audio networking protocols and interfaces exist.

See also[link]

• Analog recording vs. digital recording
• Digital audio editor
• Digital audio workstation
• Digital signal processing
• Noise shaping
• Nyquist–Shannon sampling theorem
• Quantization (signal processing)
• HTML5 Audio
• Sampling (signal processing)

Notes[link]

1. ^ Some audio signals such as those created by digital synthesis originate entirely in the digital domain, in which case analog to digital conversion does not take place.

References[link]

Sources[link]

• Borwick, John, ed., 1994: Sound Recording Practice (Oxford: Oxford University Press)
• Bosi, Marina, and Goldberg, Richard E., 2003: Introduction to Digital Audio Coding and Standards (Springer)
• Ifeachor, Emmanuel C., and Jervis, Barrie W., 2002: Digital Signal Processing: A Practical Approach (Harlow, England: Pearson Education Limited)
• Rabiner, Lawrence R., and Gold, Bernard, 1975: Theory and Application of Digital Signal Processing (Englewood Cliffs, New Jersey: Prentice-Hall, Inc.)
• Watkinson, John, 1994: The Art of Digital Audio (Oxford: Focal Press)

Noorjehan^[1][2] or Noorjehan^[3] (Punjabi, Urdu: نور جہاں) was the adopted stage name for Allah Wasai (September 21, 1926 – December 23, 2000) who was a legendary singer and actress in British India and Pakistan. Her career spanned seven decades. She was renowned as one of the greatest and most influential singers of her time in South Asia and was given the honorific title of Malika-e-Tarannum (Urdu: ملکہ ترنم, English: the queen of melody).^[2]

Born in a Punjabi family of musicians, Wasai was pushed by her parents to follow in their musical footsteps and become a singer but she was more interested in acting in films and graced the earliest Pakistani films with her performances. She holds a remarkable record of 10,000 songs to her singing credits in various languages of India and Pakistan including Urdu, Hindi, Punjabi and Sindhi languages.^[4] Along with Ahmed Rushdi, she holds the highest record of film songs in the history of Pakistani cinema. She is also considered to be the first female Pakistani film director.

In 1957, Jehan was awarded the President's Award for her acting and singing capabilities.

Early life[link]

Noor Jehan was born in Kasur, Punjab, British India^[5] and was one of the eleven children of professional musicians Madad Ali and Fateh Bibi.^[4][6]

Career[link]

Wasai began to sing at the age of five or six years old and showed a keen interest in a range of styles, including traditional folk and popular theatre. Realising her potential for singing, her mother sent her to receive early training in classical singing under Ustad Bade Ghulam Ali Khan who was also a native of Kasur. He instructed her in the traditions of the Patiala Gharana of Hindustani classical music and the classical forms of thumri, dhrupad, and khyal.^[7] At the age of nine, Wasai drew the attention of Punjabi musician Ghulam Ahmed Chishti,^[8] who would later introduce her to stage in Lahore. He composed some ghazals, naats and folk songs for her to perform, although she was more keen in breaking into acting or playback singing. Once her vocational training finished, Wasai pursued a career in singing alongside her sisters in Lahore and would usually take part in the live song and dance performances prior to screenings of films in film theatres.

The family moved to Calcutta (now Kolkata) in hope of developing the movie careers of Wasai and her sisters. During their stay in Calcutta, the renowned singer Mukhtar Begum, encouraged Wasai and her two older sisters to join film companies and recommended them to various producers. She also recommended them to her husband, Agha Hashar Kashmiri, who owned a maidan theatre (a tented theatre to accommodate large audiences). It was here that Wasai received the stage name Baby Noor Jehan. Her older sisters were offered jobs with one of the Seth Sukh Karnani companies, Indira Movietone and they went on to be known as the Punjab Mail.^[4] Wasai would later adopt Mukhtar Begum's way of performance and sari attire.

In 1935, K.D. Mehra directed Pind di Kuri in which Jehan acted along with her sisters. She next acted in a film called Missar Ka Sitara (1936) by the same company and sang in it for music composer, Damodar Sharma. Baby Noor Jehan also played the child role of Heer in the film Heer-Sayyal (1937). After a few years in Calcutta, Noor Jehan returned to Lahore in 1938. In 1939, Ghulam Haider composed songs for Jehan which led to her early popularity. She then recorded her first song Shala Jawaniyan Mane for Dalsukh M. Pancholi's movie Gul Bakavli.

In 1942, she played the main lead opposite Pran in Khadaan. It was her first role as an adult, and the film was a major success. Khandaan's success saw her shifting to Bombay, with director Syed Shaukat Hussain Rizvi. She shared melodies with Shanta Apte in Duhai (1943). It was in this film that Noor Jehan lent her voice for the second time, to another actress named Husn Bano. She married Rizvi later the same year.^[9]

In 1945 Jehan played the lead role, alongside Lata Mangeshkar and Asha Bhosle, in the movie Bari Maa.

In 1945, she achieved a milestone, when she sung a Qawwali with Zohrabai Ambalewali and Amirbai Karnataki which was "Aahen Na Bhareen Shikave Na Kiye". This was the first ever Qawwali recorded in female voices in South Asian films.

Noor Jehan's (Deepa govindarajan) last film in India was Mirza Sahibaan (1947) which starred Prithviraj Kapoor's brother Trilok Kapoor. Noor Jehan sang 127 songs in Indian films and the number of talking films she made from 1932 to 1947 was 69. The number of silents was 12. Fifty-five of her films were made in Bombay, eight in Calcutta, five in Lahore and one in Rangoon (now Yangon), Burma.

Acting career in Pakistan[link]

After the creation of Pakistan in 1947, Rizvi and Jehan decided to move to Pakistan. They left Bombay and settled in Karachi with their family.

Three years after settling in Pakistan, Noor Jehan starred in her first film in Pakistan, Chan wey (1951), opposite Santosh Kumar, which was also her first Punjabi film as a heroine. Shaukat and Noor Jehan directed this film together making Noor Jehan Pakistan's first female director. Noor Jehan's second film in Pakistan was Dopatta (1952) which turned out to be an even bigger success than Chan wey (1951).

In 1953-54, Jehan and Rizvi were divorced due to personal differences. She kept custody of the three children from their marriage. News of several affairs followed, including one with cricketer, Nazar Mohammad. In 1959, she married another actor, Ejaz Durrani, nine years her junior.^[9]

Durrani pressured her to give up acting,^[9] and her penultimate film as an actress/singer was Mirza Ghalib (1961). This contributed to the strengthening of her iconic stature. She gained another audience for herself. Her rendition of Faiz Ahmed Faiz's Mujh se pehli si mohabbat mere mehboob naj maang is a unique example of tarranum, reciting poetry as a song. Noor Jehan last acted in Baaji in 1963, though not in a leading role.

Noor Jehan bade farewell to acting in 1963 after a career of 33 years (1930 to 1963). The pressure of being a mother of six children and the demands of being a wife to another actor forced her to give up her career. Noor Jehan made 14 films in Pakistan, ten in Urdu, four in Punjabi.

Noor Jehan as a playback singer[link]

After quitting acting she took up playback singing. She made her debut as a playback singer in 1960 with the film Salma. Her first initial playback for a Pakistani film was for Jan-e-Bahar (1958), in which she sang the song Kaisa Naseeb Layi Thi, picturised on Musarrat Nazir. She received many awards, including the highest Pakistani honour in entertainment, Tamgha-e-Imtiaz (The Pride of Performance) in 1966, Pakistan's top civil award. She sang a large number of duets with Ahmed Rushdi, Mehdi Hassan, Masood Rana and Mujeeb Aalam.

She had a great understanding and friendship with many great singers of Asia, for example with the late great Alam Lohar and many more singers also.

In the 1990s Jehan also sang for then débutante actresses Neeli and Reema. For this very reason, Sabiha Khanum affectionately called her Sadabahar (evergreen). Her popularity was further boosted with her patriotic songs during the 1965 war between Pakistan and India.

Jehan visited India in 1982 to celebrate the Golden Jubilee of the Indian talkie movies, where she met Indian Prime Minister Indira Gandhi in New Delhi and was received by Dilip Kumar and Lata Mangeshkar in Mumbai.

Patriotic songs[link]

During the 1965 India-Pakistan war. Noor Jehan sung many patriotic songs enthusiastically, which became tremendously popular. Some of these songs are listed below:

• Ae watan kay sajeelay jawano, Mere naghmay tumharay leeyay hain
• Aeh putr hataan tay nahin wikday, Tu lubni ain wich bazar kuray
• Mereya dhol sipahia, Tenun Rub dyaan rakhhan
• O mahi chhail chhabilah, Haey neen kernail neen jarnail neen
• Yeh hawaoun kay musafir, Yeh samandaroun kay rahi, Meray sir bakaf mujahid, Meray suf shikan sipahe
• Rung laey ga shaheedoun ka lahoo, Yeh lahoo surkhee hay aazadi kay afsanay ki
• Mera sohnan shehr Qasoor neen, Hoya dunya wich mashhoor neen

Last years and death[link]

In 1986, on a tour of North America, Jehan suffered from chest pains and was diagnosed with angina pectoris after which she underwent a surgery to install a pacemaker. In 2000, Jehan was hospitalised in Karachi and suffered a heart attack. On December 23, 2000 Jehan died as a result of heart failure. Her funeral took place at Jamia Masjid Sultan, Karachi and she was buried at the Gizri Graveyard near the Saudi Consulate in Karachi.

Filmography[link]

References[link]

External links[link]

• Noor Jehan at the Internet Movie Database
• Noor Jehan Audio Collection - Bingo.com.pk
• Rich tributes paid to Noor Jehan - DAWN.com
• Noor Jehan's immortal melodies - DAWN.com
• The unforgettable queen - DAWN.com
• The Melody Queen lives on - DAWN.com
• ^ Songs by Noor Jehan. Retrieved 2005-04-02. Includes a photograph of Noor Jehan.
• Few hits of Noor Jehan
• Madam Noorjehan on Pakistan Film Magazine