Editing Compact Disc Digital Audio (section)

=== Further development ===
[[File:Sony-Discman-D-E307CK.jpg|thumb|Sony [[Discman]] D-E307CK portable CD player with 1-bit DAC]]

Early CD players employed binary-weighted [[digital-to-analog converter]]s (DAC), which contained individual electrical components for each bit of the DAC.<ref name=stereophile-19890501-Willenswaard>{{cite web|url=https://www.stereophile.com/content/pdm-pwm-delta-sigma-1-bit-dacs|title=PDM, PWM, Delta-Sigma, 1-Bit DACs|last=van Willenswaard|first=Peter|website=stereophile.com|date=1 May 1989|access-date=30 January 2021|archive-date=4 February 2021|archive-url=https://web.archive.org/web/20210204151933/https://www.stereophile.com/content/pdm-pwm-delta-sigma-1-bit-dacs|url-status=live}}</ref> Even when using high-precision components, this approach was prone to decoding errors.{{clarify|date=December 2021}}<ref name=stereophile-19890501-Willenswaard /> Another issue was [[jitter]], a time-related defect. Confronted with the instability of DACs, manufacturers initially turned to increasing the number of bits in the DAC and using several DACs per audio channel, averaging their output.<ref name=stereophile-19890501-Willenswaard /> This increased the cost of CD players but did not solve the core problem.

A breakthrough in the late 1980s culminated in development of the [[Delta-sigma modulation#Digital-to-analog conversion|1-bit DAC]], which converts high-resolution low-frequency digital input signal into a lower-resolution high-frequency signal that is mapped to voltages and then smoothed with an analog filter. The temporary use of a lower-resolution signal simplified circuit design and improved efficiency, which is why it became dominant in CD players starting from the early 1990s. Philips used a variation of this technique called [[pulse-density modulation]] (PDM),<ref name=stereophile-198906-Atkinson>{{cite web|url=https://www.stereophile.com/content/pdm-pwm-delta-sigma-1-bit-dacs-john-atkinson|title=PDM, PWM, Delta-Sigma, 1-Bit DACs by John Atkinson|last=Atkinson|first=John|website=stereophile.com|year=1989|access-date=30 January 2021|archive-date=4 February 2021|archive-url=https://web.archive.org/web/20210204164249/https://www.stereophile.com/content/pdm-pwm-delta-sigma-1-bit-dacs-john-atkinson|url-status=live}}</ref> while Matsushita (now [[Panasonic]]) chose [[pulse-width modulation]] (PWM), advertising it as MASH, which is an acronym derived from their patented Multi-stAge noiSe-sHaping PWM topology.<ref name=stereophile-19890501-Willenswaard />

The CD was primarily planned as the successor to the [[vinyl record]] for playing music, rather than as a data storage medium. However, CDs have grown to encompass other applications. In 1983, following the CD's introduction, Immink and [[Joseph Braat]] presented the first experiments with erasable compact discs during the 73rd [[AES Convention]].<ref>{{Cite journal
|journal=J. Audio Eng. Soc.|volume=32|date=1984|title=Experiments Toward an Erasable Compact Disc
|author=K. Schouhamer Immink and J. Braat|url=https://www.researchgate.net/publication/237764745
|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.