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{{short description|Data format used for audio compact discs}}
{{Use dmy dates|date=October 2021}}
{{Use American English|date=May 2024}}
{{Infobox storage medium
| name = Compact Disc Digital Audio
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{{optical disc authoring}}
'''Compact Disc Digital Audio''' ('''CDDA''' or '''CD-DA'''), also known as '''Digital Audio Compact Disc''' or simply as '''Audio CD''', is the [[standardization|standard]] format for audio [[compact disc]]s. The standard is defined in the '''''Red Book''''', one of a series of [[Rainbow Books]] (named for their binding colors) that contain the [[technical specification]]s for all CD [[content format|formats]]. CDDA utilizes [[pulse-code modulation]] (PCM) and uses a [[44,100 Hz]] sampling frequency and 16-bit resolution, and was originally specified to store up to 74 minutes of [[Stereophonic sound|stereo]] audio per disc.
The first commercially available audio [[CD player]], the [[Sony CDP-101]], was released in October 1982 in Japan. The format gained worldwide acceptance in 1983–84, selling more than a million CD players in those two years, to play 22.5 million discs.<ref>{{cite book |first=Ken C. |last=Pohlmann |date=2000 |title=Principles of Digital Audio |page=244 |publisher=McGraw-Hill |isbn=978-0-07-134819-5}}</ref> In the [[music industry]], audio CDs have been generally sold as either a [[CD single]] (now largely dormant), or as full-length [[Album|albums]], the latter of which has been more commonplace since the 2000s.<ref>{{Cite web |title=1999: The Year the Record Industry Lost Control |url=https://theafterword.co.uk/1999-the-year-the-record-industry-lost-control/ |access-date=2024-05-03 |website=theafterword.co.uk}}</ref>
Beginning in the 2000s, CDs were increasingly being replaced by other forms of digital storage and distribution, with the result that by 2010 the number of audio CDs being sold in the U.S. had dropped about 50% from their peak; however, they remained one of the primary distribution methods for the [[music industry]].<ref name="AutoMR-2">{{cite news | url=https://www.nytimes.com/2010/05/31/business/media/31bestbuy.html | work=The New York Times | title=As CD Sales Wane, Music Retailers Diversify | first=Joseph | last=Plambeck | date=30 May 2010 | url-status=live | archive-url=https://web.archive.org/web/20170501175846/https://www.nytimes.com/2010/05/31/business/media/31bestbuy.html | archive-date=1 May 2017 }}</ref> In the 2010s, revenues from digital music services, such as [[iTunes]], [[Spotify]], and YouTube, matched those from physical format sales for the first time.<ref>{{cite news|title=IFPI publishes Digital Music Report 2015|url=https://www.ifpi.org/news/Global-digital-music-revenues-match-physical-format-sales-for-first-time|access-date=1 July 2016|date=14 April 2015|url-status=live|archive-url=https://web.archive.org/web/20150414194629/https://www.ifpi.org/news/Global-digital-music-revenues-match-physical-format-sales-for-first-time|archive-date=14 April 2015}}</ref> According to the [[Recording Industry Association of America|RIAA]]'s midyear report in 2020, [[phonograph record]] revenues surpassed those of CDs in the U.S. for the first time since the 1980s
== History ==
The [[optophone]], first presented in 1931, was an early device that used light for both recording and playback of sound signals on a [[Negative (photography)|transparent photograph]].<ref>{{Cite web|url=https://www.radiomuseum.org/forumdata/users/5100/Funkschau_4Jg_0131_1v1_v20.pdf|title=Das Photo als Schalplatte|language=de|access-date=2 July 2020|archive-url=https://web.archive.org/web/20160404173739/https://www.radiomuseum.org/forumdata/users/5100/Funkschau_4Jg_0131_1v1_v20.pdf|archive-date=4 April 2016|url-status=live}}</ref> More than thirty years later, American inventor [[James Russell (inventor)|James T. Russell]] has been credited with inventing the first system to record digital media on a photosensitive plate. Russell's patent application was filed in 1966, and he was granted a patent in 1970.<ref>{{cite patent |country=US |number=3,501,586 |title=Analog to digital to optical photographic recording and playback system |pubdate=1970-03-17 |fdate=1966-09-01}}</ref> Following litigation, [[Sony]] and [[Philips]] licensed Russell's patents for recording in 1988.<ref>{{cite press release |date=2000 |publisher=Reed College public affairs office |title=Inventor and physicist James Russell '53 will receive Vollum Award at Reed's convocation |access-date=24 July 2014 |url=https://reed.edu/news_center/press_releases/2000-2001/288.html |archive-url=https://web.archive.org/web/20131009170700/https://www.reed.edu/news_center/press_releases/2000-2001/288.html |archive-date=9 October 2013 }}</ref><ref>{{cite web|url=https://web.mit.edu/invent/iow/russell.html |title=Inventor of the Week – James T. Russell – The Compact Disc |date=December 1999 |publisher=[[MIT]] |archive-url=https://web.archive.org/web/20030417162935/https://web.mit.edu/invent/iow/russell.html |archive-date=17 April 2003 }}</ref> It is debatable whether Russell's concepts, patents, and prototypes instigated and in some measure influenced the compact disc's design.<ref>{{cite news |newspaper=The Seattle Times |url=https://seattletimes.com/html/businesstechnology/2002103322_cdman29.html |author=Brier Dudley |title=Scientist's invention was let go for a song |date=29 November 2004 |access-date=24 July 2014 |archive-url=https://web.archive.org/web/20140810225444/https://seattletimes.com/html/businesstechnology/2002103322_cdman29.html |archive-date=10 August 2014}}</ref>
The compact disc is an evolution of [[LaserDisc]] technology,{{r|Immink}} where a focused [[laser]] beam is used that enables the high information density required for high-quality digital audio signals. Unlike the prior art by Optophonie and James Russell, the information on the disc is read from a reflective layer using a laser as a light source through a protective substrate. Prototypes were developed by Philips and Sony independently in the late 1970s.<ref>{{cite web|title=The History of the CD|url=
=== Digital audio laser-disc prototypes ===
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Philips coined the term ''compact disc'' in line with another audio product, the [[Compact Cassette]],<ref name="peek">{{cite journal |first=Hans B. |last=Peek |title=The Emergence of the Compact Disc |journal=IEEE Communications Magazine |date=January 2010 |pages=10–17 |volume=48 |number=1 |issn=0163-6804 |doi=10.1109/MCOM.2010.5394021 |s2cid=21402165 }}</ref> and contributed the general manufacturing [[Industrial process|process]], based on video LaserDisc technology. Philips also contributed [[eight-to-fourteen modulation]] (EFM), while Sony contributed the [[error-correction]] method, [[Cross-Interleaved Reed-Solomon Coding|CIRC]], which offers resilience to defects such as scratches and fingerprints.
''The Compact Disc Story'',<ref name="Immink" /> told by a former member of the task force, gives background information on the many technical decisions made, including the choice of the sampling frequency, playing time, and disc diameter. The task force consisted of around 6 persons,<ref name="Immink2" /><ref name="Knopper">{{cite book | title = Appetite for Self-Destruction: The Rise and Fall of the Record Industry in the Digital Age | author = Knopper, Steve | publisher = Free Press | date = 7 January 2009 | access-date = <!-- 2009-038-17 --> }}</ref> though according to Philips, the compact disc was "invented collectively by a large group of people working as a team
=== Initial launch and adoption ===
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|pages=531–538|access-date=2 February 2018}}</ref> In June 1985, the computer-readable [[CD-ROM]] (read-only memory) and, in 1990, recordable [[CD-R]] discs were introduced.{{efn|The world's first CD-R was made by the Japanese firm [[Taiyo Yuden]] Co., Ltd. in 1988 as part of the joint Philips-Sony development effort.}} Recordable CDs became an alternative to tape for recording and distributing music and could be duplicated without degradation in sound quality.
Other newer video formats such as [[DVD]] and [[Blu-ray]] use the same physical geometry as CD, and most DVD and Blu-ray players are [[backward compatible]] with audio CDs.▼
=== Peak ===
CD sales in the United States peaked by 2000.<ref name="statista">{{cite web |last1=Richter |first1=Felix |title=The Rise and Fall of the Compact Disc |url=https://www.statista.com/chart/12950/cd-sales-in-the-us/ |website=Statista |access-date=13 October 2019 |archive-url=https://web.archive.org/web/20191013073724/https://www.statista.com/chart/12950/cd-sales-in-the-us/ |archive-date=13 October 2019 |url-status=live }}</ref> By the early 2000s, the CD player had largely replaced the [[Compact Cassette|audio cassette]] player as standard equipment in new automobiles, with 2010 being the final model year for any car in the United States to have a factory-equipped cassette player.<ref name=nyt20120718>{{cite news|url=https://www.nytimes.com/2011/02/06/automobiles/06AUDIO.html|title=For Car Cassette Decks, Play Time Is Over|last=Williams|first=Stephen|newspaper=New York Times|date=4 February 2011|access-date=18 July 2012|url-status=live|archive-url=https://web.archive.org/web/20121110105333/https://www.nytimes.com/2011/02/06/automobiles/06AUDIO.html|archive-date=10 November 2012}}</ref>
Two new formats were marketed in the 2000s designed as successors to the CD: the [[Super Audio CD]] (SACD) and [[DVD-Audio]]. However neither of these were adopted partly due to increased relevance of digital (virtual) music and the apparent lack of audible improvements in audio quality to most human ears.<ref>{{Cite web |title=Journal of the AES » 2007 September - Volume 55 Number 9 |url=https://www.aes.org/journal/online/JAES_V55/9/ |access-date=2024-05-03 |website=www.aes.org |language=en}}</ref> These effectively extended the CD's longetivity in the music market.<ref>{{Cite web |title=Blu-ray is to DVD as SACD was to CD: Better, but not enough better? |url=https://www.cnet.com/tech/home-entertainment/blu-ray-is-to-dvd-as-sacd-was-to-cd-better-but-not-enough-better/ |access-date=2024-05-03 |website=CNET |language=en}}</ref>
▲Other newer video formats such as [[DVD]] and [[Blu-ray]] use the same physical geometry as CD, and most DVD and Blu-ray players are [[backward compatible]] with audio CDs.
=== Decline ===
With the advent and popularity of [[Digital distribution|Internet-based distribution]] of files in [[Lossy compression|lossy-compressed]] [[audio format]]s such as [[MP3]], sales of CDs began to decline in the 2000s. For example, between 2000 and 2008, despite overall growth in music sales and one anomalous year of increase, major-label CD sales declined overall by 20%.<ref name="AutoMR-11">{{cite news |first=Ethan |last=Smith |title=Music Sales Decline for Seventh Time in Eight Years: Digital Downloads Can't Offset 20% Plunge in CD Sales |url=https://www.wsj.com/articles/SB123075988836646491?mod=rss_whats_news_technology&mg=com-wsj |newspaper=Wall Street Journal |date=2 January 2009 |access-date=4 March 2009 |url-status=live |archive-url=https://web.archive.org/web/20171020191140/https://www.wsj.com/articles/SB123075988836646491?mod=rss_whats_news_technology&mg=com-wsj |archive-date=20 October 2017 }}</ref> Despite rapidly declining sales year-over-year, the pervasiveness of the technology lingered for a time, with companies placing CDs in pharmacies, supermarkets, and filling station convenience stores to target buyers less likely to be able to use Internet-based distribution.<ref name="AndItsEnd" /> In 2012, CDs and DVDs made up only 34% of music sales in the United States.<ref>{{cite web|url=https://www.tokyotimes.com/buying-cds-continues-to-be-a-tradition-in-japan/|title=Buying CDs continues to be a tradition in Japan – Tokyo Times|date=23 August 2013|access-date=30 December 2016|url-status=live|archive-url=https://web.archive.org/web/20161220150903/https://www.tokyotimes.com/buying-cds-continues-to-be-a-tradition-in-japan/|archive-date=20 December 2016}}</ref> By 2015, only 24% of music in the United States was purchased on physical media, two thirds of this consisting of CDs;<ref>{{Cite web|url=https://riaa.com/media/238E8AC7-3810-A95C-44DC-B6DEB46A3C6E.pdf|title=News and Notes on 2015 Mid-Year RIAA Shipment and Revenue Statistics|last=Friedlander|first=Joshua P.|year=2015|publisher=Recording Industry Association of America|archive-url=https://web.archive.org/web/20150930135150/https://riaa.com/media/238E8AC7-3810-A95C-44DC-B6DEB46A3C6E.pdf|archive-date=30 September 2015}}</ref> however, in the same year in Japan, over 80% of music was bought on CDs and other physical formats.<ref>Sisaro, Ben. ''New York Times'' 11 June 2015: {{cite news|url=https://www.nytimes.com/2015/06/12/business/media/line-music-a-new-streaming-service-aims-at-japanese-market.html?_r=0|title=Music Streaming Service Aims at Japan, Where CD Is Still King|newspaper=The New York Times|date=11 June 2015|archive-url=https://web.archive.org/web/20171020191923/https://www.nytimes.com/2015/06/12/business/media/line-music-a-new-streaming-service-aims-at-japanese-market.html?_r=0|archive-date=20 October 2017|url-status=live|access-date=26 August 2017|last1=Sisario|first1=Ben}}</ref> In 2018, U.S. CD sales were 52 million units—less than 6% of the peak sales volume in 2000.<ref name="statista" /> In the UK, 32 million units were sold, almost 100 million fewer than in 2008.<ref>{{citation |title=Is this the end of owning music? |work=BBC News |date=3 January 2019 |url=https://www.bbc.com/news/entertainment-arts-46735093 |access-date=3 March 2021 |archive-date=8 November 2020 |archive-url=https://web.archive.org/web/20201108002704/https://www.bbc.com/news/entertainment-arts-46735093 |url-status=live }}</ref> In 2018, [[Best Buy]] announced plans to decrease their focus on CD sales, however, while continuing to sell records, sales of which are growing during the [[vinyl revival]].<ref name="bestverge">{{cite web |last=Ong |first=Thuy |date=6 February 2018 |title=Best Buy will stop selling CDs as digital music revenue continues to grow |url=https://www.theverge.com/2018/2/6/16973538/bestbuy-target-cd-sales-vinyl-cassette |url-status=live |archive-url=https://web.archive.org/web/20180206181746/https://www.theverge.com/2018/2/6/16973538/bestbuy-target-cd-sales-vinyl-cassette |archive-date=6 February 2018 |access-date=6 February 2018 |website=[[The Verge]]}}</ref><ref>{{cite news |last=Owsinski |first=Bobby |date=7 July 2018 |title=Best Buy, Winding Down CD Sales, Pounds Another Nail Into The Format's Coffin |url=https://www.forbes.com/sites/bobbyowsinski/2018/07/07/best-buy-cd-sales/amp/ |url-status=live |archive-url=https://web.archive.org/web/20180806211709/https://www.forbes.com/sites/bobbyowsinski/2018/07/07/best-buy-cd-sales/amp/ |archive-date=6 August 2018 |access-date=6 August 2018 |work=Forbes}}</ref><ref>{{cite news |author=Chris Morris |date=2 July 2018 |title=End of a Era: Best Buy Significantly Cuts Back on CDs |url=https://fortune.com/2018/07/02/best-buy-ends-cd-sales/ |url-status=live |archive-url=https://web.archive.org/web/20180714110206/https://fortune.com/2018/07/02/best-buy-ends-cd-sales/ |archive-date=14 July 2018 |access-date=6 August 2018 |work=Fortune}}</ref>
During the 2010s, the increasing popularity of solid-state media and music streaming services caused automakers to remove automotive CD players in favor of [[minijack]] auxiliary inputs, wired connections to USB devices and wireless [[Bluetooth]] connections.<ref name="Biersdorfer">{{cite news |last1=Biersdorfer |first1=J.D. |title=Hand Me the AUX Cord |url=https://www.nytimes.com/2017/03/17/technology/personaltech/hand-me-the-aux-cord.html |access-date=12 January 2022 |work=The New York Times |date=March 17, 2017 |archive-date=12 January 2022 |archive-url=https://web.archive.org/web/20220112053206/https://www.nytimes.com/2017/03/17/technology/personaltech/hand-me-the-aux-cord.html |url-status=live }}</ref> Automakers viewed CD players as using up valuable space and taking up weight which could be reallocated to more popular features, like large touchscreens.<ref name="Ramey">{{cite news |last1=Ramey |first1=Jay |title=Do You Want a CD Player in a New Car? |url=https://www.autoweek.com/car-life/classic-cars/a35459280/do-you-want-a-cd-player-in-a-new-car/ |access-date=12 January 2022 |work=Autoweek |date=February 9, 2021 |archive-date=27 August 2023 |archive-url=https://web.archive.org/web/20230827104052/https://www.autoweek.com/car-life/classic-cars/a35459280/do-you-want-a-cd-player-in-a-new-car/ |url-status=live }}</ref> By 2021, only [[Lexus]] and [[General Motors]] were still including CD players as standard equipment with certain vehicles.<ref name="Ramey" />
=== Current status ===
CDs continued to be strong in some markets such as Japan where 132 million units were produced in 2019.<ref>{{Cite web|url=https://www.nippon.com/en/japan-data/h00740/|title=Physical Formats Still Dominate Japanese Music Market|date=24 June 2020|website=nippon.com|access-date=14 November 2022|archive-date=28 October 2022|archive-url=https://web.archive.org/web/20221028183640/https://www.nippon.com/en/japan-data/h00740/|url-status=live}}</ref>
The decline in CD sales has slowed in recent years; in 2021, CD sales increased in the US for the first time since 2004,<ref>{{cite web | url=https://www.strata-gee.com/lets-get-physical-vinyl-sales-up-51-cd-sales-up-for-first-time-in-17-yrs/ | title=Let's Get Physical! Vinyl Sales up >51%, CD Sales up for First Time in 17-yrs | website=Strata-gee.com | date=26 January 2022 | access-date=14 November 2022 | archive-date=14 November 2022 | archive-url=https://web.archive.org/web/20221114140242/https://www.strata-gee.com/lets-get-physical-vinyl-sales-up-51-cd-sales-up-for-first-time-in-17-yrs/ | url-status=live }}</ref> with [[Axios (website)|Axios]] citing its rise to "young people who are finding they like hard copies of music in the digital age".<ref>{{Cite web|url=https://www.makeuseof.com/cd-sales-are-rising-again-but-why/|title=CD Sales Are Rising Again, but Why?|first=Patrick|last=Kariuki|date=18 March 2022|website=Makeuseof.com|access-date=14 November 2022|archive-date=27 August 2023|archive-url=https://web.archive.org/web/20230827104056/https://www.makeuseof.com/cd-sales-are-rising-again-but-why/|url-status=live}}</ref> It came at the same time as both vinyl and cassette reached sales levels not seen in 30 years.<ref>{{Cite web|url=https://www.officialcharts.com/chart-news/vinyl-and-cassette-uk-sales-continue-to-surge-to-30-year-high-as-cd-sales-decline-slows__34839/|title=Vinyl and cassette UK sales continue to surge to 30 year high|website=Officialcharts.com|access-date=14 November 2022|archive-date=27 August 2023|archive-url=https://web.archive.org/web/20230827104058/https://www.officialcharts.com/chart-news/vinyl-and-cassette-uk-sales-continue-to-surge-to-30-year-high-as-cd-sales-decline-slows__34839/|url-status=live}}</ref> The RIAA reported that CD revenue made a dip in 2022, before increasing again in 2023 and overtook downloading for the first time in over a decade.<ref>https://www.riaa.com/wp-content/uploads/2024/03/2023-Year-End-Revenue-Statistics.pdf</ref>▼
In the US, 33.4 million CD albums were sold in the year 2022.<ref>{{Cite web |title=Physical album shipments in the U.S. 2022 |url=https://www.statista.com/statistics/186772/album-shipments-in-the-us-music-industry-since-1999/ |access-date=2024-05-03 |website=Statista |language=en}}</ref> In [[France]] in 2023, 10.5 million CDs were sold, almost double that of vinyl, but both of them represented generated 12% each of the French music industry revenues.<ref>{{Cite web |last=Bazoge |first=Mickaël |date=2024-03-27 |title=En France comme aux États-Unis, les vinyles en position de force face aux CD |url=https://www.01net.com/actualites/en-france-comme-aux-etats-unis-les-vinyles-en-position-de-force-face-aux-cd.html |access-date=2024-05-03 |website=01net.com |language=fr-FR}}</ref>
▲The decline in CD sales has slowed in recent years; in 2021, CD sales increased in the US for the first time since 2004,<ref>{{cite web | url=https://www.strata-gee.com/lets-get-physical-vinyl-sales-up-51-cd-sales-up-for-first-time-in-17-yrs/ | title=Let's Get Physical! Vinyl Sales up >51%, CD Sales up for First Time in 17-yrs | website=Strata-gee.com | date=26 January 2022 | access-date=14 November 2022 | archive-date=14 November 2022 | archive-url=https://web.archive.org/web/20221114140242/https://www.strata-gee.com/lets-get-physical-vinyl-sales-up-51-cd-sales-up-for-first-time-in-17-yrs/ | url-status=live }}</ref> with [[Axios (website)|Axios]] citing its rise to "young people who are finding they like hard copies of music in the digital age".<ref>{{Cite web|url=https://www.makeuseof.com/cd-sales-are-rising-again-but-why/|title=CD Sales Are Rising Again, but Why?|first=Patrick|last=Kariuki|date=18 March 2022|website=Makeuseof.com|access-date=14 November 2022|archive-date=27 August 2023|archive-url=https://web.archive.org/web/20230827104056/https://www.makeuseof.com/cd-sales-are-rising-again-but-why/|url-status=live}}</ref> It came at the same time as both vinyl and cassette reached sales levels not seen in 30 years.<ref>{{Cite web|url=https://www.officialcharts.com/chart-news/vinyl-and-cassette-uk-sales-continue-to-surge-to-30-year-high-as-cd-sales-decline-slows__34839/|title=Vinyl and cassette UK sales continue to surge to 30 year high|website=Officialcharts.com|access-date=14 November 2022|archive-date=27 August 2023|archive-url=https://web.archive.org/web/20230827104058/https://www.officialcharts.com/chart-news/vinyl-and-cassette-uk-sales-continue-to-surge-to-30-year-high-as-cd-sales-decline-slows__34839/|url-status=live}}</ref>
=== Awards and accolades ===
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There was a long debate over the use of 16-bit (Sony) or 14-bit (Philips) [[Quantization (signal processing)|quantization]], and 44,056 or 44,100 samples/s (Sony) or approximately 44,000 samples/s (Philips). When the Sony/Philips task force designed the Compact Disc, Philips had already developed a 14-bit [[Digital-to-analog converter|D/A converter]] (DAC), but Sony insisted on 16-bit. In the end Sony won, so 16 bits and 44.1 kilosamples per second prevailed. Philips found a way to produce 16-bit quality using its 14-bit DAC by using four times [[oversampling]].<ref name=Immink />
Some early CDs were mastered with [[Emphasis (telecommunications)|pre-emphasis]], an artificial boost of high audio frequencies. The pre-emphasis improves the apparent signal-to-noise ratio by making better use of the channel's dynamic range. On playback, the player applies a de-emphasis filter to restore the frequency response curve to an overall flat one. Pre-emphasis time constants are 50
Four-channel, or [[quadraphonic]], supported was originally intended to be included in CD-DA.<ref>{{Cite book|url = https://books.google.com/books?id=jqwgBQAAQBAJ&q=Four-channel+Compact+Disc+Digital+Audio&pg=PA108|title = Digital Audio and Compact Disc Technology|isbn = 978-1-4831-4039-1|last1 = Baert|first1 = Luc|last2 = Theunissen|first2 = Luc|last3 = Vergult|first3 = Guido|date = 2013-10-22| publisher=Newnes |access-date = 27 August 2023|archive-date = 27 August 2023|archive-url = https://web.archive.org/web/20230827104057/https://books.google.com/books?id=jqwgBQAAQBAJ&q=Four-channel+Compact+Disc+Digital+Audio&pg=PA108|url-status = live}}</ref> The Red Book specification briefly mentioned a four-channel mode in its June 1980,<ref name="RedBook1980">"Red Book" Audio CD specification, June 1980, Sony/Philips</ref> September 1983,<ref name="RedBook1983">"Red Book" Audio CD specification, September 1983, Sony/Philips</ref> and November 1991<ref name="RedBook1991">"Red Book" Audio CD specification, November 1991, Sony/Philips</ref> editions. On the first page, it lays out the "Main parameters" of the CD system, including: "Number of channels: 2 and/or 4 simultaneously[*] sampled." The footnote says, "In the case of more than two channels the encoder and decoder diagrams have to be adapted."
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== Storage capacity and playing time ==
The creators of the CD originally aimed at a playing time of 60 minutes with a disc diameter of 100 mm (Sony) or 115 mm (Philips).<ref name=Immink2 /> Sony vice-president [[Norio Ohga]] suggested extending the capacity to 74 minutes to accommodate the recording of [[Wilhelm Furtwängler]] conducting [[Ludwig van Beethoven]]'s [[Symphony No. 9 (Beethoven)|Ninth Symphony]] at the 1951 [[Bayreuth Festival]].<ref name="PhilBeet" /><ref name="Auto45-6" /> The additional 14-minute playing time
According to a ''[[Sunday Tribune]]'' interview,<ref name="ferguscassidy" /> the story is slightly more involved. In 1979, Philips owned [[PolyGram]], one of the world's largest music distributors
The 74-minute playing time of a CD, which is longer than the 22 minutes per side<ref name="Auto45-7" /><ref name="Auto45-8" /> typical of [[LP record|long-playing]] (LP) [[vinyl album]]s, was often used to the CD's advantage during the early years when CDs and LPs vied for commercial sales. CDs would often be released with one or more [[bonus
Playing times beyond 74 minutes are achieved by decreasing track pitch (the distance separating the track as it spirals the disc). However, most players can still accommodate the more closely spaced data if it is still within ''Red Book'' tolerances.<ref name="Auto45-9" /> Manufacturing processes used in the final years of CD technology allowed an audio CD to contain up to 82 minutes (variable from one replication plant to another) without requiring the content creator to sign a waiver releasing the plant owner from responsibility if the CD produced is marginally or entirely unreadable by some playback equipment. In this final practice, maximum CD playing time crept higher by reducing minimum engineering tolerances.
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| Mirabilis Records
| 1990
| 80:51<ref name="ambisonic.info">{{Cite web|url=https://ambisonic.info/mirabilis.html|title=Ambisonic Info
|-
| ''JS Bach, Das Orgelbüchlein''
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|Hot Action/Universal 930 003
|2006
|88:41 on disc 1, 89:07 on disc 2<ref>{{Cite web|url=https://www.discogs.com/Die-%C3%84rzte-B%C3%A4st-Of/release/806980|title=Die Ärzte – Bäst Of|website=Discogs |access-date=31 January 2021|language=en-US|archive-date=21 February 2021|archive-url=https://web.archive.org/web/20210221082151/https://www.discogs.com/Die-%C3%84rzte-B%C3%A4st-Of/release/806980|url-status=live}}</ref>{{rs|reason=Let's find a source that discusses this extraordinary length|date=May 2024}}
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== External links ==
* [https://www.ip.philips.com/licensing/program/15 Philips' Audio Standards licensing info]
* [https://www.webstore.iec.ch/preview/info_iec60908%7Bed2.0%7Db.pdf IEC 60908:1999 Audio recording – Compact disc digital audio system] {{Webarchive|url=https://web.archive.org/web/20240226010330/https://webstore.iec.ch/preview/info_iec60908%7Bed2.0%7Db.pdf |date=26 February 2024 }}
* [https://wiki.multimedia.cx/index.php?title=PCM#Red_Book_CD_Audio MultimediaWiki article about PCM and ''Red Book'' CD Audio]
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