Editing Compact Disc Digital Audio (section)

=== Digital audio laser-disc prototypes ===
In 1974, Lou Ottens, director of the audio division of Philips, started a small group to develop an analog optical audio disc with a diameter of {{cvt|20|cm}} and a sound quality superior to that of the vinyl record.<ref>{{cite news |url=https://www.laweekly.com/music/why-cds-may-actually-sound-better-than-vinyl-5352162 |title=Why CDs may actually sound better than vinyl] |archive-url=https://web.archive.org/web/20160409132701/https://www.laweekly.com/music/why-CDs-may-actually-sound-better-than-vinyl-5352162 |archive-date=9 April 2016 |first=Chris |last=Kornelis |date=27 January 2015}}</ref> However, due to the unsatisfactory performance of the analog format, two Philips research engineers recommended a digital format in March 1974. In 1977, Philips then established a laboratory with the mission of creating a digital audio disc. The diameter of Philips's prototype compact disc was set at {{cvt|11.5|cm}}, the diagonal of an audio cassette.{{r|Immink}}{{r|peek}}

[[Heitaro Nakajima]], who developed an early digital audio recorder within Japan's national public broadcasting organization, [[NHK]], in 1970, became general manager of Sony's audio department in 1971. In 1973, his team developed a digital [[PCM adaptor]] that made audio recordings using a [[Betamax]] video recorder. After this, in 1974 the leap to storing digital audio on an optical disc was easily made.<ref>{{cite magazine | url=https://books.google.com/books?id=kw0EAAAAMBAJ&pg=PA68 | title=Heitaro Nakajima | magazine=Billboard | date=8 January 2000 | access-date=4 November 2014 | author=McClure, Steve | pages=68 | url-status=live | archive-url=https://web.archive.org/web/20150319065246/https://books.google.com/books?id=kw0EAAAAMBAJ&pg=PA68 | archive-date=19 March 2015 }}</ref> Sony first publicly demonstrated an optical digital audio disc in September 1976. A year later, in September 1977, Sony showed the press a {{cvt|30|cm}} disc that could play an hour of digital audio (44,100&nbsp;Hz sampling rate and 16-bit resolution) using [[modified frequency modulation]] encoding.<ref name="SonyHistorical">{{cite journal |url=https://www.aes.org/e-lib/browse.cfm?elib=2912 |url-access=subscription |title = A Long Play Digital Audio Disc System | date = March 1979 |website=Audio Engineering Society | access-date = 14 February 2009 | url-status = live | archive-url = https://web.archive.org/web/20090725223113/https://www.aes.org/e-lib/browse.cfm?elib=2912 | archive-date = 25 July 2009 }}</ref> 

In September 1978, Sony demonstrated an optical digital audio disc with a 150-minute playing time, 44,056&nbsp;Hz sampling rate, 16-bit linear resolution, and [[cross-interleaved Reed-Solomon coding]] (CIRC) [[error correction code]]—specifications similar to those later settled upon for the standard compact disc format in 1980. Technical details of Sony's digital audio disc were presented during the 62nd [[Audio Engineering Society|AES]] Convention, held on 13–16 March 1979, in [[Brussels]].{{r|SonyHistorical}} Sony's AES technical paper was published on 1 March 1979. A week later, on 8 March, Philips publicly demonstrated a prototype of an optical digital audio disc at a press conference called "Philips Introduce Compact Disc"{{r|BBC6950933}} in [[Eindhoven]], Netherlands.<ref name="PhilipsHistorical">{{cite web | url = https://www.philipsmuseumeindhoven.nl/phe/products/e_cd.htm | title = Philips Compact Disc | publisher = Philips | access-date = 14 February 2009 | archive-url = https://web.archive.org/web/20090319141821/https://www.philipsmuseumeindhoven.nl/phe/products/e_cd.htm | archive-date = 19 March 2009 }}</ref> Sony executive [[Norio Ohga]], later CEO and chairman of Sony, and [[Heitaro Nakajima]] were convinced of the format's commercial potential and pushed further development despite widespread skepticism.<ref name="Ohgaobituary">{{ citation | url = https://www.foxnews.com/tech/sony-chairman-credited-with-developing-cds-dies | title = Sony chairman credited with developing CDs dies | access-date = 14 October 2012 | work = Fox News | date = 24 April 2011 | url-status = live | archive-url = https://web.archive.org/web/20130521044524/https://www.foxnews.com/world/2011/04/24/sony-chairman-credited-developing-cds-dies/ | archive-date = 21 May 2013 }}</ref>