Media type | Optical disc |
---|---|
Encoding | 2 channels of LPCM audio, each signed 16-bit values sampled at 44100 Hz |
Capacity | up to 74–80 minutes (up to 24 minutes for mini 8 cm CD) |
Read mechanism | Semiconductor laser (780 nm wavelength) |
Standard | IEC 60908 |
Developed by | Sony & Philips |
Usage | Audio storage |
Extended to | DVD-Audio |
Released | 1982 |
Optical discs |
---|
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 technical specifications, which is why the format is also dubbed "Redbook audio" in some contexts.[1] 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 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.[2] In the music industry, audio CDs have been generally sold as either a CD single (now largely dormant), or as full-length albums, the latter of which has been more commonplace since the 2000s.[3]
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.[4] In the 2010s, revenues from digital music services, such as iTunes, Spotify, and YouTube, matched those from physical format sales for the first time.[5] According to the RIAA's midyear report in 2020, phonograph record revenues surpassed those of CDs in the U.S. for the first time since the 1980s,[6][7] whereas in Japan, the CD remains the premier music format, and revenues have grown in 2022,[8] and in Germany it outsold other physical formats at least fourfold in 2022.[9]