Audio levels display on a digital audio recorder (Zoom H4n)
Indigital recording, anaudio orvideo signal is converted into a stream ofdiscrete numbers representing the changes over time inair pressure for audio, orchroma andluminance 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 originalanalog audio or video forms so that they can be heard or seen.
1943:Bell Telephone Laboratories develops the first PCM-based digital scrambled speech transmission system,SIGSALY,[4] in response to German interception of military telephone traffic duringWorld War II. The twelve transmission points were retired after the war.
1957:Max Mathews of Bell Labs recorded the first computer-generated music, a 17-second piece called "The Silver Scale" composed by his co-worker Newman Guttman.[6]
1967: The first commercial PCM encoder (monaural) was developed byNHK's research facilities in Japan.[3] The 30 kHz 12-bit device used acompander (similar toDBX Noise Reduction) to extend the dynamic range, and stored the signals on avideo tape recorder.
1969: NHK expands the PCM encoder's capabilities to two-channelstereo and 32 kHz 13-bit resolution.[3]
1970:James Russell patents the first digital-to-optical recording and playback system,[9] which would later lead to theCompact Disc.
January 1971: Using NHK's experimental PCM recording system, Dr. Takeaki Anazawa, an engineer atDenon, recordsthe world's first commercial digital recordings,The World Of Stomu Yamash'ta 1 & 2 byStomu Yamash'ta (January 11, 1971)[3] andSomething bySteve Marcus & Jiro Inagaki (January 25, 1971). Both had to be recorded live, without edits. Marcus is released first (on LP, in February 1972), making it thefirst released digital recording. On January 27, Yamash'ta recordsMetempsychosis in the Nippon Columbia studio, Tokyo, with percussion and a brass section.
1972: Using lessons learned from the NHK encoder,Denon unveils a desk-sized 8-channel PCM encoder, the DN-023R, which uses 47.25 kHz 13-bit PCM resolution and 4-head open reel broadcastvideo tape recorder.[3] The first recording with this new system is theSmetana Quartet performingMozart'sString QuartetsK.458 andK.421, recorded in Tokyo April 24–26 and released that October. At least six other Denon-recorded digitalLP records are released in October, including jazz, classical and traditional Japanese music.[10][3][11]
December 12–19, 1974:Helmuth Rilling records threeBach organ works inside the Gedächtniskirche,Stuttgart Germany using the DN-023RA.[13] Between 1974 and 1977, over 250 PCM recordings were made by Denon, the majority recorded in Japan.
May 1975:University of Utah professorThomas Stockham develops a PCM digital audio recorder of his own design, using computer tape drives as the storage system. He founds the companySoundstream to offer it commercially.[14] 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 (equivalent to $876,531 in 2024) each. Over 200 recordings were made on his equipment, almost as many as the Denon PCM.[14][15]
1976: The prototypeSoundstream 37.5 kHz, 16-bit, 2-channel recorder[3] is used to record theSanta Fe Opera performingVirgil Thomson's operaThe Mother of Us All forNew World Records, making itthe first US digital recording. However, the digital recorder is just a backup to the main analogmulti-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 1976AES Convention in New York, but never commercially released.
January 1977: Denon develops a smaller fully-portable PCM recording system, the DN-034R. Like the DN-023R and DN-023RA it records 8 channels at 47.25 kHz on a 2-inch video tape recorder (VTR) running at 38.1 cm/s, but it uses 14 bits "with emphasis, making it equivalent to 15.5 bits," yielding 89 dBsignal-to-noise ratio. It also allowed foroverdubbing for the first time with the use of a second VTR, crucial for professional recording.[3]
September 1977: Sony introduces the PCM-1 Audio Unit ($4400 street price equivalent to $6,985 in 2019)[16] (44.056 kHz, 14-bit), the first consumer PCM encoder. It required the use of a home video tape recorder for storage.[17]
November 4–7, 1977:3M demonstrates a prototype 2-channel 50.4 kHz 16-bit digital recorder running on 1-inch tape at45 ips at the New York AES Convention.[3] As no true 16-bit converters were available, it combined separate 12-bit and 8-bit converters to create 16-bit performance.[18]
November 28, 1977: Denon brings their DN-034R toNew York City's Sound Ideas Studios and recordsArchie Shepp'sOn Green Dolphin Street, making itAmerica's firstreleased digitally recorded commercial album.[3] Five other jazz albums are recorded with the DN-034R in New York before it returns to Japan in December.[19][failed verification]
March 1978: Sony introduces the professional-gradePCM-1600 at a list price of US$40,000 (equivalent to $192,837 in 2024)[21] used with an externalU-matic tape drive, making digital recording commercially available to recording studios for the first time. PCM-1610 and PCM-1630 follow.[22][23][24]
June 2, 1978:Sound 80 studios in Minneapolis records theSaint Paul Chamber Orchestra performingAaron Copland'sAppalachian Spring. This session is set up as adirect-to-disc recording, with the prototype3M 50.4 kHz digital recorder running in the background. There is some disagreement,[3][26] 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.[27] In 1984 the session is re-released onCompact Disc by ProArte. This recording was nominated for threeGrammy Awards, winning "Best Chamber Music Performance" (1980),[18][28] making it thefirst digital recording to win a Grammy.
Early June 1978:Sound 80 recordsFlim and the BB's debut self-titled album as anotherdirect to disc recording again with the experimental3M 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 thefirst 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, noCompact Disc release is possible. The compact disc release of the Saint Paul Chamber Orchestra, which used the same machine, is unexplained.
August 27, 1979:Giorgio Moroder'sE=MC² is released, thefirst electronic live-to-digital LP recorded on Soundstream PCM.
September 4, 1979: Scoring begins for Star Trek The Motion Picture soundtrack, recorded tomultitrack analog, mastered to digital stereo tape for LP release to coincide with film debut December 6, 1979.[34]
October 12, 1979:Fleetwood Mac'sTusk is released on LP. It, andLive, December 8, 1980, were mastered on the Soundstream PCM from analog multi-tracks.[14]
December 1, 1979: The Grammy Award-winning self-titledChristopher Cross album is released. Cross' album becomes thefirst digitally recorded album to chart (recorded on the 3M system) in the United States, eventually winning 5 Grammys. Digital recording is now mainstream.
1980:Mitsubishi Electric introduces the X-80ProDigiopen reel 1/4" tape15 ips 50.4 kHz 16-bit digital recorder ($5000 equivalent to $19,081 in 2024). Only 200 are sold worldwide.[37]
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 kHzCompact Disc and the company is out of business after 1983.[14]
1981: Sony releases the PCM-F1 Digital Audio Processor ($1900 equivalent to $6,571 in 2024) (44.056 kHz, 16-bit) and matching SL-2000Betamax VCR ($700 equivalent to $2,421 in 2024) as a complete affordable portable (with optional batteries) home digital recording system[38]
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.
1982: Sony releases the PCM-501ESPCM adaptor (44.1 kHz, 16-bit) ($895 list price), which is used with an externalVHS orBetamax video recorder.[citation needed]
1982: Sony introducesDigital Audio Stationary Head standard (DASH) for digital audio recording on 1/4" open reel tape. Recorders supporting variations of DASH were as well produced by Studer and TASCAM.
August 17, 1982:Claudio Arrau's March 1979 analog recording ofFrederic Chopin waltzes (Philips 400 025) becomesthe first classical Compact Disc ever commercially manufactured.[39][40] It is made by the Philips plant inLangenhagen,Hanover RegionGermany. 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: Thefirst popular Compact Disc ever manufactured,ABBA's 1981 albumThe Visitors (selected because it was "mostly digitally recorded")[41] 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 (titledSecurity in North America andPeter Gabriel IV elsewhere).[42] When released on CD in October 1984 it becomes the first full-digitalDDD release. It was recorded onSony's Mobile One digital studio[43] and mixed to a Sony PCM-1610.[44]
October 1, 1982: Thefirstcompact disc players are marketed by Sony (CDP-101, $900 equivalent to $2,932 in 2024) and Philips (CD-100, $700 equivalent to $2,281 in 2024).[45]
November 26–28, 1982: Flim & the BB's record their second studio album,Tricycle. Released in early 1983, it becomes thefirst non-classical fully digital CD to be released. (Later given aSPARS code of DD).
March 2, 1983: CD players and 16 CDs fromCBS Records are introduced in the United States.[49]
12 November 1984: American singerMadonna's second studio albumLike a Virgin is released. It became the first digitally recorded album that topped theBillboard 200 chart.
13 May 1985: English rock bandDire Straits' fifth studio albumBrothers in Arms is released. It became the best-selling digitally recorded album of the 80s, and the first album whose CDs' sales outsold LPs'.
1991: Alesis Digital Audio Tape (ADAT) is a tape format used for simultaneously recording eight tracks ofdigital audio at once, ontoSuper VHS magnetic tape – a format similar to that used by consumerVCRs. The product was announced in January 1991 at theNAMM Show. The first ADAT recorders shipped over a year later in February or March 1992.[52]
September 1992: Sony announces itsMiniDisc format.
1993: Random Access Digital Audio Recorder (RADAR) is the first single box device used for simultaneously recording 24 tracks ofdigital audio at once, onto hard disk drives. The product, manufactured byCreation Technologies was announced in October 1993 at the AES Convention in New York. The first RADAR recorders shipped in August 1994.
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 measurement 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 thesample rate 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.
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 theloudspeakers.
Fordigital cassettes, thetape head moves as well as the tape, typically in ahelical scan configuration, in order to maintain a high enough speed to keep the bits at a manageable size.
Foroptical disc recording technologies such asCD-R, alaser is used to alter the optical properties of the dye layer of the medium. A weaker laser is used to read these patterns.
As stated by theNyquist–Shannon sampling theorem, to preventaliasing, the audio signal must be sampled at a rate at least twice that of the highest frequency component in the signal. For music-quality audio,44.1 and 48 kHz sampling rates are the most common.
Master recording may be done at a higher sampling rate (i.e., 88.2, 96, 176.4 or 192 kHz). High-resolution PCM recordings have been released onDVD-Audio (also known as DVD-A),DualDisc (utilizing the DVD-Audio layer), orHigh Fidelity Pure Audio on Blu-ray. In addition, it is possible to release a high-resolution recording as either an uncompressedWAV or lossless compressedFLAC file[56] (usually at 24 bits) withoutdown-converting it. There remains controversy about whether higher sampling rates provide any verifiable benefit to the consumer product.[57]
When aCompact Disc (theCD Red Book standard is 44.1 kHz 16 bit) is to be made from a high-res recording, the recording must bedown-converted to 44.1 kHz. This is done as part of themastering process.
Beginning in the 1980s, music that was recorded, mixed or mastered digitally was often labeled using theSPARS code to describe which processes were analog and which were digital. Since digital recording has become near-ubiquitous, the SPARS codes are now rarely used.
One of the advantages of digital recording over analog recording is its resistance to errors. Once the signal is in the digital format, it is not subject togeneration loss from copying. Instead of the gradual degradation experienced with analog media, digital media is subject to acliff effect.
^Peek, Hans; Bergmans, Jan; Van Haaren, Jos; Toolenaar, Frank; Stan, Sorin (2009).Origins and Successors of the Compact Disc (Philips Research Book Series, Volume 11). Springer Science+Business Media B.V. p. 10.ISBN978-1-4020-9552-8.
^Kees Schouhamer Immink (March 1991)."The future of digital audio recording".Journal of the Audio Engineering Society.47:171–172.Keynote address was presented to the 104th Convention of the Audio Engineering Society in Amsterdam during the society's golden anniversary celebration on May 17, 1998.
^Coalson, Josh."FLAC - news".flac.sourceforge.net. Retrieved9 April 2018.
