In digital recording, an audio or video signal is converted into a stream of discrete numbers representing the changes over time in air pressure for audio, or chroma and luminance values for video. This number stream is saved to a storage device. To play back a digital recording, the numbers are retrieved and converted back into their original

analog Analog or analogue may refer to: Computing and electronics * Analog signal, in which information is encoded in a continuous variable ** Analog device, an apparatus that operates on analog signals *** Analog electronics, circuits which use analog ...

audio or video forms so that they can be heard or seen. In a properly matched

analog-to-digital converter In electronics, an analog-to-digital converter (ADC, A/D, or A-to-D) is a system that converts an analog signal, such as a sound picked up by a microphone or light entering a digital camera, into a digital signal. An ADC may also provide ...

(ADC) and

digital-to-analog converter In electronics, a digital-to-analog converter (DAC, D/A, D2A, or D-to-A) is a system that converts a digital signal into an analog signal. An analog-to-digital converter (ADC) performs the reverse function. There are several DAC archit ...

(DAC) pair the analog signal is accurately reconstructed per the constraints of the

Nyquist–Shannon sampling theorem The Nyquist–Shannon sampling theorem is a theorem in the field of signal processing which serves as a fundamental bridge between continuous-time signals and discrete-time signals. It establishes a sufficient condition for a sample rate that per ...

dependent on the sampling rate and quantization error dependent on the audio or video bit depth. Because the signal is stored digitally, assuming proper error detection and correction, the recording is not degraded by copying, storage or interference.

Timeline

*October 3, 1938: British telephone engineer Alec Harley Reeves files at the French Patent Office the first patent describing the technique known today as

pulse-code modulation Pulse-code modulation (PCM) is a method used to digitally represent sampled analog signals. It is the standard form of digital audio in computers, compact discs, digital telephony and other digital audio applications. In a PCM Stream (comp ...

(PCM). On November 22, 1939, Reeves files also in the US. It was first proposed as a telephony technology. *1943:

Bell Telephone Laboratories Nokia Bell Labs, originally named Bell Telephone Laboratories (1925–1984), then AT&T Bell Laboratories (1984–1996) and Bell Labs Innovations (1996–2007), is an American industrial research and scientific development company owned by mult ...

develops the first PCM-based digital scrambled speech transmission system, SIGSALY, in response to German interception of military telephone traffic during

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposing ...

. The twelve transmission points were retired after the war. *June 1950:

Differential pulse-code modulation Differential pulse-code modulation (DPCM) is a signal encoder that uses the baseline of pulse-code modulation (PCM) but adds some functionalities based on the prediction of the samples of the signal. The input can be an analog signal or a digital ...

(DPCM) developed by C. Chapin Cutler at Bell Labs. *1957: Max Mathews of Bell develops the process to digitally record sound on a computer. *1967: The first monaural PCM encoder was developed by

NHK , also known as NHK, is a Japanese public broadcaster. NHK, which has always been known by this romanized initialism in Japanese, is a statutory corporation funded by viewers' payments of a television license fee. NHK operates two terrestr ...

's research facilities in Japan. The 30 kHz 12-bit device used a

compander In telecommunication and signal processing, companding (occasionally called compansion) is a method of mitigating the detrimental effects of a channel with limited dynamic range. The name is a portmanteau of the words compressing and expanding, ...

(similar to DBX Noise Reduction) to extend the dynamic range, and stored the signals on a video tape recorder. *1969: NHK expands the PCM encoder's capabilities to two-channel stereo and 32 kHz 13-bit resolution. *1969: The

charge-coupled device A charge-coupled device (CCD) is an integrated circuit containing an array of linked, or coupled, capacitors. Under the control of an external circuit, each capacitor can transfer its electric charge to a neighboring capacitor. CCD sensors are a ...

, the first image sensor used in digital imaging, invented by Willard S. Boyle and

George E. Smith George Elwood Smith (born May 10, 1930) is an American scientist, applied physicist, and co-inventor of the charge-coupled device (CCD). He was awarded a one-quarter share in the 2009 Nobel Prize in Physics for "the invention of an imaging semico ...

at Bell Labs, based on

MOS capacitor The metal–oxide–semiconductor field-effect transistor (MOSFET, MOS-FET, or MOS FET) is a type of field-effect transistor (FET), most commonly fabricated by the controlled oxidation of silicon. It has an insulated gate, the voltage of which d ...

technology. *1970: James Russell patents the first digital-to-optical recording and playback system, which would later lead to the Compact Disc. *January 1971: Using NHK's experimental PCM recording system, Dr. Takeaki Anazawa, an engineer at Denon, records the world's first commercial digital recordings, ''The World Of Stomu Yamash'ta 1 & 2'' by Stomu Yamash'ta (January 11, 1971) and ''Something'' by Steve Marcus & Jiro Inagaki (January 25, 1971). Both had to be recorded live, without edits. Marcus is released first (in February 1972), making it the first released digital recording. On January 27 Yamash'ta records ''Metempsychosis'' in the Nippon Columbia studio, Tokyo, with percussion and a brass section. *1972: Using lessons learned from the NHK encoder, Denon unveils the first 8-channel PCM encoder, the DN-023R, which uses 47.25 kHz 13-bit PCM resolution and 4-head open reel broadcast video tape recorder. The first recording with this new system is the Smetana Quartet performing Mozart's ''String Quartets K.458 and K.421'', recorded in Tokyo April 24–26 and released that October. At least six other Denon-recorded digital LP records are released in October, including jazz, classical and traditional Japanese music. *1973: Adaptive differential pulse-code modulation (ADPCM) developed by P. Cummiskey,

Nikil Jayant Nikil S. Jayant (1945 -- ) is an Indian-American communications engineer. He was a prominent long-term researcher at Bell Laboratories and subsequently a professor at Georgia Institute of Technology. He received his Ph.D. in Electrical Communicatio ...

and

James L. Flanagan James Loton Flanagan (August 26, 1925 – August 25, 2015) was an American electrical engineer. He was Rutgers University's vice president for research until 2004. He was also director of Rutgers' Center for Advanced Information Processing and t ...

at Bell Labs. *December 2–3, 1974: The Paillard Chamber Orchestra records the first digital recording outside Japan, in

Paris Paris () is the Capital city, capital and List of communes in France with over 20,000 inhabitants, most populous city of France, with an estimated population of 2,165,423 residents in 2019 in an area of more than 105 km² (41 sq mi), ma ...

' Notre Dame Cathedral, using Denon's DN-023R.

Bach Johann Sebastian Bach (28 July 1750) was a German composer and musician of the late Baroque period. He is known for his orchestral music such as the ''Brandenburg Concertos''; instrumental compositions such as the Cello Suites; keyboard wor ...

's "

The Musical Offering ''The Musical Offering'' (German: or ), Bach-Werke-Verzeichnis, BWV 1079, is a collection of keyboard canon (music), canons and fugues and other pieces of music by Johann Sebastian Bach, all based on a single musical Subject (music), theme given ...

" (BWV 1079) is released on LP May 1975. *December 12–19, 1974:

Helmuth Rilling Helmuth Rilling (born 29 May 1933) is a German choral conductor and an academic teacher. He is the founder of the Gächinger Kantorei (1954), the Bach-Collegium Stuttgart (1965), the Oregon Bach Festival (1970), the Internationale Bachakademie ...

records three

organ works inside the Gedächtniskirche, Stuttgart Germany using the DN-023R. *May 1975: University of Utah professor

Thomas Stockham Thomas Greenway Stockham (December 22, 1933 – January 6, 2004) was an American scientist who developed one of the first practical digital audio recording systems, and pioneered techniques for digital audio recording and processing. He also l ...

develops a PCM digital audio recorder of his own design, using computer tape drives as the storage system. He founds the company Soundstream to offer it commercially. Between 1977 and 1980 a total of eighteen 4-channel 50 kHz 16-bit units were manufactured, of which seven were sold at about US$150,000 () each. Over 200 recordings were made on his equipment, almost half of all digital classical recordings made in the 1970s. *1976: The prototype Soundstream 37.5 kHz, 16-bit, 2-channel recorder is used to record the

Santa Fe Opera Santa Fe Opera (SFO) is an American opera company, located north of Santa Fe, New Mexico. After creating the ''Opera Association of New Mexico'' in 1956, its founding director, John Crosby, oversaw the building of the first opera house on a newl ...

performing

Virgil Thomson Virgil Thomson (November 25, 1896 – September 30, 1989) was an American composer and critic. He was instrumental in the development of the "American Sound" in classical music. He has been described as a modernist, a neoromantic, a neoclass ...

's opera '' The Mother of Us All'' for

New World Records New World Records is a record label that was established in 1975 through a Rockefeller Foundation grant to celebrate America's bicentennial (1976) by producing a 100-LP anthology, with American music from many genres.multi-track recorder, and the analog recording is deemed superior and thus used for the LP release. The backup digital tape was presented at the October 1976 AES Convention in New York, but never commercially released. *1977: Denon develops the smaller portable PCM recording system, the DN-034R. Like the DN-023R it records 8 channels at 47.25 kHz, but it uses 14-bits "with emphasis, making it equivalent to 15.5 bits." It also allowed for overdubbing for the first time, crucial for professional recording. *September 1977: Sony introduces the PCM-1 Audio Unit ($4400 street price ) (44.056 kHz, 14-bit), the first consumer PCM encoder. It required the use of a home video tape recorder for storage. *November 4–7, 1977: 3M demonstrates a prototype 2-channel 50.4 kHz 16-bit digital recorder running on 1-inch tape at at the New York AES Convention. As no true 16-bit converters were available, it combined separate 12-bit and 8-bit converters to create 16-bit performance. *November 28, 1977: Denon brings their DN-034R to

New York City New York, often called New York City or NYC, is the most populous city in the United States. With a 2020 population of 8,804,190 distributed over , New York City is also the most densely populated major city in the Un ...

's Sound Ideas Studios and records

Archie Shepp Archie Shepp (born May 24, 1937) is an American jazz saxophonist, educator and playwright who since the 1960s has played a central part in the development of avant-garde jazz. Biography Early life Shepp was born in Fort Lauderdale, Florida, but ...

's ''On Green Dolphin Street'', making it America's first digitally-recorded commercial album. The following two days, November 29–30, Frank Foster records '' Manhattan Fever'' which is released April 1978. Five other jazz albums are recorded with the DN-034R in New York before it returns to Japan in December. *January 1978: Soundstream's first commercial release, '' Diahann Carroll With the Duke Ellington Orchestra Under The Direction Of

Mercer Ellington Mercer Kennedy Ellington (March 11, 1919 – February 8, 1996) was an American musician, composer, and arranger. His father was Duke Ellington, whose band Mercer led for 20 years after his father's death. Biography Early life and education Ellin ...

– A Tribute To

Ethel Waters Ethel Waters (October 31, 1896 – September 1, 1977) was an American singer and actress. Waters frequently performed jazz, swing, and pop music on the Broadway stage and in concerts. She began her career in the 1920s singing blues. Her no ...

'', appears *March 1978: Sony introduces the professional-grade PCM-1600 at a list price of US$40,000 () used with an external U-matic tape drive, making digital recording commercially available to recording studios for the first time. PCM-1610 and PCM-1630 follow. *April 4–5, 1978:

Telarc Telarc International Corporation is an American audiophile independent record label founded in 1977 by two classically trained musicians and former teachers, Jack Renner (recording engineer), Jack Renner and Robert Woods (producer), Robert Woods. ...

uses Soundstream's PCM system to record Frederick Fennell and his Eastman Wind Ensemble playing

Gustav Holst Gustav Theodore Holst (born Gustavus Theodore von Holst; 21 September 1874 – 25 May 1934) was an English composer, arranger and teacher. Best known for his orchestral suite ''The Planets'', he composed many other works across a range ...

's ''Suites for Military Band'' and George Frideric Handel's ''

Music for the Royal Fireworks The ''Music for the Royal Fireworks'' ( HWV 351) is a suite in D major for wind instruments composed by George Frideric Handel in 1749 under contract of George II of Great Britain for the fireworks in London's Green Park on 27 April 1749. The ...

.'' When released on LP this became the first US-recorded digital classical release. *June 2, 1978: Sound 80 studios in Minneapolis records the

Saint Paul Chamber Orchestra The Saint Paul Chamber Orchestra (SPCO) is a full-time professional chamber orchestra based in Saint Paul, Minnesota. In collaboration with five Artistic Partners, the orchestra's musicians present more than 130 concerts and educational programs ea ...

performing

Aaron Copland Aaron Copland (, ; November 14, 1900December 2, 1990) was an American composer, composition teacher, writer, and later a conductor of his own and other American music. Copland was referred to by his peers and critics as "the Dean of American Com ...

's '' Appalachian Spring''. This session is set up as a

direct to disc recording Direct-to-disc recording refers to sound recording methods that bypass the use of magnetic tape recording and record audio directly onto analog disc masters. Professional analog sound recording Most sound recordings for records before the 1950s ...

, with the prototype 3M 50.4 kHz digital recorder running in the background. There is some disagreement, but it appears the resulting LP record (Sound80 Records S80-DLR-101) was taken from the digital backup tapes rather than the direct-to-disc acetate. In 1984 the session is re-released on Compact Disc by ProArte. This recording was nominated for three Grammy Awards, winning " Best Chamber Music Performance" (1980), making it the first digital recording to win a Grammy. *Early June 1978: Sound 80 records '' Flim and the BB's'' debut self-titled album as another

again with the experimental 3M recorder in the background. Again the acetate is deemed not as good as the digital backup, so the digital master is used for the LP record (Sound80 Records S80-DLR-102). This makes it the first U.S. non-classical digital release. Within 6 months the hand-built ("very bulky and finicky") 3M digital recorder is disassembled, rendering the non-standard master tape unplayable. Therefore, no Compact Disc release is possible. The compact disc release of the Saint Paul Chamber Orchestra, which used the same machine, is unexplained. *March 8, 1979: The first prototype Compact Disc player is demonstrated by Philips in Eindhoven,

Netherlands ) , anthem = ( en, "William of Nassau") , image_map = , map_caption = , subdivision_type = Sovereign state , subdivision_name = Kingdom of the Netherlands , established_title = Before independence , established_date = Spanish Netherl ...

. Prototype CDs played on the unit were a pressing of Antonio Vivaldi's '' Le quattro stagione'' played by Vittorio Negri and the Kammerorchester Berlin (Philips 9500 100, recorded analog 1976), and Joseph Haydn's ''String Quartet No. 31''(?). A third prototype disc, on

Archiv Produktion Archiv Produktion is a classical music record label of German origin. It originated in 1949 as a classical label for the Deutsche Grammophon Gesellschaft (DGG), and in 1958 Archiv was established as a subsidiary of DGG, specialising in recording ...

is pictured but the details are not legible. The text indicates it might be

Franz Schubert Franz Peter Schubert (; 31 January 179719 November 1828) was an Austrian composer of the late Classical and early Romantic eras. Despite his short lifetime, Schubert left behind a vast ''oeuvre'', including more than 600 secular vocal wo ...

's '' Unfinished Symphony''.

Herbert von Karajan Herbert von Karajan (; born Heribert Ritter von Karajan; 5 April 1908 – 16 July 1989) was an Austrian conductor. He was principal conductor of the Berlin Philharmonic for 34 years. During the Nazi era, he debuted at the Salzburg Festival, wit ...

and the

Berlin Philharmonic The Berlin Philharmonic (german: Berliner Philharmoniker, links=no, italic=no) is a German orchestra based in Berlin. It is one of the most popular, acclaimed and well-respected orchestras in the world. History The Berlin Philharmonic was fo ...

's recording of Richard Strauss's '' Eine Alpensinfonie'' is also mentioned as a contender for earliest test pressing of a CD, but it was not recorded until December 1–3, 1980. *July 11, 1979: The first U.S.-recorded digitally-recorded LP of

popular music Popular music is music with wide appeal that is typically distributed to large audiences through the music industry. These forms and styles can be enjoyed and performed by people with little or no musical training.Popular Music. (2015). ''Fu ...

(with vocals), '' Bop Till You Drop'' by guitarist Ry Cooder, was released by Warner Bros. Records. The album was recorded in

Los Angeles Los Angeles ( ; es, Los Ángeles, link=no , ), often referred to by its initials L.A., is the List of municipalities in California, largest city in the U.S. state, state of California and the List of United States cities by population, sec ...

on a 32-track digital machine built by the 3M corporation. *August 27, 1979: Giorgio Moroder's '' E=MC²'' is released, the first electronic live-to-digital LP recorded on Soundstream PCM. *October 12, 1979: Fleetwood Mac's ''

Tusk Tusks are elongated, continuously growing front teeth that protrude well beyond the mouth of certain mammal species. They are most commonly canine teeth, as with pigs and walruses, or, in the case of elephants, elongated incisors. Tusks share ...

'' is released on LP. It, and '' Live'', December 8, 1980, were mastered on the Soundstream PCM from analog multi-tracks. *October 30, 1979: Stevie Wonder releases his soundtrack album, ''

Journey Through the Secret Life of Plants Journey or journeying may refer to: * Travel, the movement of people between distant geographical locations ** Day's journey, a measurement of distance ** Road trip, a long-distance journey on the road Animals * Journey (horse), a thoroughbred ra ...

'' recorded and processed on a Sony PCM-1600. *December 1, 1979: The Grammy Award-winning self-titled '' Christopher Cross'' album is released. Cross' album becomes the first digitally recorded album to chart (recorded on the 3M system) in the United States, eventually winning 5 Grammys. Digital recording is now mainstream. *1980: The Red Book standard (44.1 kHz, 16-bit) is established for

Compact Disc Digital Audio Compact Disc Digital Audio (CDDA or CD-DA), also known as Digital Audio Compact Disc or simply as Audio CD, is the standard format for audio compact discs. The standard is defined in the ''Red Book'', one of a series of Rainbow Books (named ...

. *1980: Mitsubishi Electric introduces the X-80

ProDigi Mitsubishi's ProDigi was a professional audio, reel-to-reel, digital audio tape format with a stationary head position, similar to Sony's Digital Audio Stationary Head, which competed against ProDigi when the format was available in the mid- ...

open reel Reel-to-reel audio tape recording, also called open-reel recording, is Magnetic tape#Audio, magnetic tape audio recording in which the recording tape is spooled between reels. To prepare for use, the ''supply reel'' (or ''feed reel'') contain ...

1/4" tape 50.4 kHz 16-bit digital recorder ($5000 ). Only 200 are sold worldwide. *1980: Soundstream merges with Digital Recording Corporation, becoming DRC/Soundstream, to develop and market 50 kHz PCM recording to an optical card. This is subsequently eclipsed by the rise of the 44.1 kHz Compact Disc and the company is out of business after 1983. *1981: Sony releases the PCM-F1 Digital Audio Processor ($1900 ) (44.056 kHz, 16-bit) and matching SL-2000 Betamax VCR ($700 ) as a complete affordable portable (with optional batteries) home digital recording system *1981: Technics releases the SV-P100 digital audio recorder suitable for both professional (digital mastering) and consumer (home use) recording. It used PCM 14-bit recording on a VHS format cassette tape, resulting in an up to 3 hours programme of 2-channel stereo recording. *August 17, 1982:

Claudio Arrau Claudio Arrau León (; February 6, 1903June 9, 1991) was a Chilean pianist known for his interpretations of a vast repertoire spanning the baroque to 20th-century composers, especially Bach, Beethoven, Schubert, Chopin, Schumann, Liszt and B ...

's March 1979 analog recording of Frederic Chopin waltzes (Philips 400 025) becomes the first classical Compact Disc ever commercially manufactured. It is made by the Philips plant in Langenhagen, Hanover Region

Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...

. Arrau himself was invited to press the button to start the manufacture. This CD was not actually released until 1983 so it presumably ran into manufacturing problems like the ABBA release (below). *August 17, 1982: The first popular Compact Disc ever manufactured, ABBA's 1981 album '' The Visitors'' (selected because it was "mostly digitally recorded") is produced at the same plant. However, due to production problems with it the third version didn't actually hit stores until March 1983. *September 5, 1982: Peter Gabriel releases his fourth studio album (titled ''Security'' in North America and ''Peter Gabriel IV'' elsewhere). When released on CD in October 1984 it becomes the first full-digital DDD release. It was recorded on Sony's Mobile One digital studio and mixed to a Sony PCM-1610. *October 1, 1982: The first compact disc players are marketed by Sony (CDP-101, $900 ) and Philips (CD-100, $700 ). *October 1, 1982: Billy Joel's analog-recorded ''

52nd Street 52nd Street is a -long one-way street traveling west to east across Midtown Manhattan, New York City. A short section of it was known as the city's center of jazz performance from the 1930s to the 1950s. Jazz center Following the repeal of ...

'' becomes the first CD to hit the market in Japan, beating out ABBA's '' The Visitors'' and Claudio Arrau's Chopin Waltzes. Forty-nine other CDs are released in Japan on the same day including Toto's '' Turn Back'', Pink Floyd's '' Wish You Were Here'' and Michael Jackson's '' Off the Wall''. *October 1982: New England Digital offers the Sample-to-Disk

hard disk recorder A hard disk recorder (HDR) is a system that uses a high-capacity hard disk to record digital audio or digital video. Hard disk recording systems represent an alternative to reel-to-reel audio tape recording and video tape recorders, and provide ...

option on the Synclavier, the first commercial hard disk recording system. *November 26–28, 1982: Flim & the BB's record their second studio album, ''Tricycle''. Released in early 1983, it becomes the first non-classical fully digital CD to be released. (Later given a

SPARS code The SPARS code is a three-position alphabetic classification system developed in the early 1980s by the Society of Professional Audio Recording Services (SPARS) for commercial compact disc releases to denote aspects of the sound recording and re ...

of DD). *March 2, 1983: CD players and 16 CDs from

CBS Records CBS Records may refer to: * CBS Records or CBS/Sony, former name of Sony Music, a global record company * CBS Records International, label for Columbia Records recordings released outside North America from 1962 to 1990 * CBS Records (2006), founde ...

are introduced in the United States. *1984: Sony releases the PCM-501ES

PCM adaptor A PCM adaptor is a device that encodes digital audio as video for recording on a videocassette recorder. The adapter also has the ability to decode a video signal back to digital audio for playback. This digital audio system was used for mast ...

(44.1 kHz, 16-bit) ($895 list price) which is used with an external VHS or Betamax video recorder. *September 1984: Bruce Springsteen's '' Born in the U.S.A.'' becomes the first US-manufactured CD to be released. *12 November 1984: American singer Madonna's second studio album '' Like a Virgin'' is released. It became the first digitally-recorded album that topped the ''Billboard'' 200 chart. *13 May 1985: English rock band Dire Straits' fifth studio album '' Brothers in Arms'' is released. It became the best-selling digitally-recorded album of the 80s, and the first album whose CDs' sales outsold LPs'. *1987: Sony develops Digital Audio Tape. *1989: Test broadcasts for NICAM stereo digital audio for broadcast TV began in the UK. *1990: Digital radio begins in

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

, using the L-Band. *1991: Alesis Digital Audio Tape ( ADAT) is a tape format used for simultaneously recording eight tracks of digital audio at once, onto Super VHS magnetic tape – a format similar to that used by consumer

VCR A videocassette recorder (VCR) or video recorder is an electromechanical device that records analog audio and analog video from broadcast television or other source on a removable, magnetic tape videocassette, and can play back the recording. ...

s. The product was announced in January 1991 at the NAMM convention. The first ADAT recorders shipped over a year later in February or March 1992. *1993: Random Access Digital Audio Recorder ( RADAR) is the first single box device used for simultaneously recording 24 tracks of digital audio at once, onto hard disk drives. The product, manufactured by Creation Technologies was announced in October 1993 at the AES convention in New York. The first RADAR recorders shipped in August 1994. *1996: Optical discs and DVD players begin selling in Japan. *1999:

Ricky Martin Enrique Martín Morales (born December 24, 1971), known professionally as Ricky Martin, is a Puerto Rican singer, songwriter, and actor. He is known for his musical versatility, with his Ricky Martin albums discography, discography spanning ...

's " Livin' la Vida Loca" becomes the first No. 1 single to be recorded, edited, and mixed fully within a

digital audio workstation A digital audio workstation (DAW) is an electronic device or application software used for recording, editing and producing audio files. DAWs come in a wide variety of configurations from a single software program on a laptop, to an integrat ...

. Produced by

Charles Dye Charles Dye is a Grammy-nominated and Latin Grammy-winning record producer, engineer and mixer from Hollywood, Florida, USA. Grammy In 2001, Dye received a Latin Grammy for Best Engineered Album for Thalía's ''Arrasando''. Other production cr ...

and Desmond Child using

Pro Tools Pro Tools is a digital audio workstation (DAW) developed and released by Avid Technology (formerly Digidesign) for Microsoft Windows and macOS. It is used for music creation and production, sound for picture ( sound design, audio post-produ ...

Process

Recording # The analog signal is transmitted from the input device to an

(ADC). # The ADC converts this signal by repeatedly measuring the momentary level of the analog (audio) wave and then assigning a binary number with a given quantity of bits (word length) to each measurment point. The longer the word length the more precise the representation of the original audio wave level. # The frequency at which the ADC measures the level of the analog wave is called the

sample rate In signal processing, sampling is the reduction of a continuous-time signal to a discrete-time signal. A common example is the conversion of a sound wave to a sequence of "samples". A sample is a value of the signal at a point in time and/or spa ...

or sampling rate. The higher the sampling rate the higher the upper audio frequency of the digitized audio signal. # The ADC outputs a sequence of digital audio samples that make up a continuous stream of 0s and 1s. # These binary numbers are stored on recording media such as magnetic tape, a hard drive,

optical drive In computing, an optical disc drive is a disc drive that uses laser light or electromagnetic waves within or near the visible light spectrum as part of the process of reading or writing data to or from optical discs. Some drives can only r ...

or in

solid state memory A solid-state drive (SSD) is a solid-state storage device that uses integrated circuit assemblies to store data persistently, typically using flash memory, and functioning as secondary storage in the hierarchy of computer storage. It is ...

. Playback # The sequence of numbers is transmitted from storage into a

(DAC) # The DAC converts the numbers back to an analog signal by sticking together the level information stored in each digital sample, thus rebuilding the original analog waveform. # This signal is amplified and transmitted to the loudspeakers.

Recording of bits

Techniques to record to commercial media

For digital cassettes, the

tape head A tape head is a type of transducer used in tape recorders to convert electrical signals to magnetic fluctuations and vice versa. They can also be used to read credit/debit/gift cards because the strip of magnetic tape on the back of a credit card ...

moves as well as the tape, typically in a helical scan configuration, in order to maintain a high enough speed to keep the bits at a manageable size. For

optical disc recording technologies Optical disc authoring requires a number of different optical disc recorder technologies working in tandem, from the optical disc media to the firmware to the control electronics of the optical disc drive. Types of recordable optical disc The ...

such as

CD-R CD-R (Compact disc-recordable) is a digital optical disc storage format. A CD-R disc is a compact disc that can be written once and read arbitrarily many times. CD-R discs (CD-Rs) are readable by most CD readers manufactured prior to the i ...

, a laser is used to alter the optical properties of the dye layer of the medium. A weaker laser is used to read these patterns.

Parameters of digital audio recording

Word size

The number of

bit The bit is the most basic unit of information in computing and digital communications. The name is a portmanteau of binary digit. The bit represents a logical state with one of two possible values. These values are most commonly represente ...

s used to represent a sampled audio wave (the '' word size'') directly affects the resulting noise in a recording after intentionally added

dither Dither is an intentionally applied form of noise used to randomize quantization error, preventing large-scale patterns such as color banding in images. Dither is routinely used in processing of both digital audio and video data, and is often ...

, or the

distortion In signal processing, distortion is the alteration of the original shape (or other characteristic) of a signal. In communications and electronics it means the alteration of the waveform of an information-bearing signal, such as an audio signa ...

of an undithered signal. The number of possible voltage levels at the output is simply the number of levels that may be represented by the largest possible digital number (the number 2 raised to the power of the number of bits in each sample). There are no “in between” values allowed. If there are more bits in each sample the waveform is more accurately traced, because each additional bit doubles the number of possible values. The distortion is roughly the percentage that the least significant bit represents out of the average value. Distortion (as a percentage) in digital systems increases as signal levels decrease, which is the opposite of the behavior of analog systems.

Sample rate

If the sampling rate is too low, the original audio signal cannot be reconstructed from the sampled signal. As stated by the

, to prevent

aliasing In signal processing and related disciplines, aliasing is an effect that causes different signals to become indistinguishable (or ''aliases'' of one another) when sampled. It also often refers to the distortion or artifact that results when ...

, the audio signal must be sampled at a rate at least twice that of the highest frequency component in the signal. For recording music-quality audio, the following PCM sampling rates are the most common: 44.1, 48, 88.2, 96, 176.4, and 192 kHz, each with an upper-frequency limit half the sampling frequency. When making a recording, experienced audio recording and mastering engineers will often do a master recording at a higher sampling rate (i.e. 88.2, 96, 176.4 or 192 kHz) and then do any editing or mixing at that same higher frequency to avoid aliasing errors. High resolution PCM recordings have been released on DVD-Audio (also known as DVD-A), DAD (Digital Audio Disc, which utilizes the stereo PCM audio tracks of a regular DVD),

DualDisc The DualDisc is a type of double-sided optical disc product developed by a group of record companies including Michael Jackson, MJJ Productions Inc., EMI, EMI Music, Universal Music Group, Sony BMG, Sony BMG Music Entertainment, Warner Music Group, ...

(utilizing the DVD-Audio layer), or High Fidelity Pure Audio on Blu-ray. In addition it is possible to release a high resolution recording as either an uncompressed WAV or lossless compressed FLAC file (usually at 24 bits) without down-converting it. There remains some controversy whether higher sampling rates actually provide any verifiable benefit in the consumer product when using modern anti-aliasing filters. When a Compact Disc (the CD Red Book standard is 44.1 kHz 16 bit) is to be made from a high-res recording, the recording must be down-converted to 44.1 kHz, or originally recorded at that rate. This is done as part of the mastering process. Beginning in the 1980s, music that was recorded, mixed and/or mastered digitally was often labelled using the

to describe which processes were analog and which were digital. Since digital recording has become near-ubiquitous the SPARS codes are now rarely used.

Error rectification

One of the advantages of digital recording over analog recording is its resistance to errors. Once the signal is in the digital format, it will not be degraded (add noise or distortion) from copying or storage.

References

{{DEFAULTSORT:Digital Recording Sound Video Sound recording