The compact disc (CD) is a digital optical disc data storage format that was co-developed by Philips and Sony to store and play digital audio recordings. The first compact disc was manufactured in August 1982, and was first released in Japan in October 1982 as Compact Disc Digital Audio. The CD gained rapid popularity in the 1990s. It quickly outsold all other audio formats in the United States by 1991, ending the market dominance of the cassette tape. By 2000, the CD accounted for 92.3% of the entire market share in regard to music sales. The rise of MP3, iTunes, cellular ringtones, and other downloadable music formats in the mid-2000s ended the decade-long dominance of the CD.
In telecommunication, a line code is a pattern of voltage, current, or photons used to represent digital data transmitted down a communication channel or written to a storage medium. This repertoire of signals is usually called a constrained code in data storage systems. Some signals are more prone to error than others as the physics of the communication channel or storage medium constrains the repertoire of signals that can be used reliably.
Compact Disc Digital Audio, 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, one of a series of Rainbow Books that contain the technical specifications for all CD formats.
MiniDisc (MD) is an erasable magneto-optical disc-based data storage format offering a capacity of 60, 74, and later, 80 minutes of digitized audio.
Super Audio CD (SACD) is an optical disc format for audio storage introduced in 1999. It was developed jointly by Sony and Philips Electronics and intended to be the successor to the compact disc (CD) format.
A CD player is an electronic device that plays audio compact discs, which are a digital optical disc data storage format. CD players were first sold to consumers in 1982. CDs typically contain recordings of audio material such as music or audiobooks. CD players may be part of home stereo systems, car audio systems, personal computers, or portable CD players such as CD boomboxes. Most CD players produce an output signal via a headphone jack or RCA jacks. To use a CD player in a home stereo system, the user connects an RCA cable from the RCA jacks to a hi-fi and loudspeakers for listening to music. To listen to music using a CD player with a headphone output jack, the user plugs headphones or earphones into the headphone jack.
In computing, an optical disc drive is a disc drive that uses laser light or electromagnetic waves within or near the visible light spectrum as part of the process of reading or writing data to or from optical discs. Some drives can only read from certain discs, but recent drives can both read and record, also called burners or writers. Compact discs, DVDs, and Blu-ray discs are common types of optical media which can be read and recorded by such drives.
Direct Stream Digital (DSD) is a trademark used by Sony and Philips for their system for digitally encoding audio signals for the Super Audio CD (SACD).
A magneto-optical drive is a kind of optical disc drive capable of writing and rewriting data upon a magneto-optical disc. 130 mm (5.25 in) and 90 mm (3.5 in) discs were the most common sizes. In 1983, just a year after the introduction of the compact disc, Kees Schouhamer Immink and Joseph Braat presented the first experiments with erasable magneto-optical compact discs during the 73rd AES Convention in Eindhoven. The technology was introduced commercially in 1985. Although optical, they normally appear as hard disk drives to an operating system and can be formatted with any file system. Magneto-optical drives were common in some countries, such as Japan, but have fallen into disuse.
In telecommunications, 8b/10b is a line code that maps 8-bit words to 10-bit symbols to achieve DC balance and bounded disparity, and at the same time provide enough state changes to allow reasonable clock recovery. This means that the difference between the counts of ones and zeros in a string of at least 20 bits is no more than two, and that there are not more than five ones or zeros in a row. This helps to reduce the demand for the lower bandwidth limit of the channel necessary to transfer the signal.
In digital recording, an audio or video signal is converted into a stream of discrete numbers representing the changes over time in air pressure for audio, or chroma and luminance 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 original analog audio or video forms so that they can be heard or seen.
Eight-to-fourteen modulation (EFM) is a data encoding technique – formally, a line code – used by compact discs (CD), laserdiscs (LD) and pre-Hi-MD MiniDiscs. EFMPlus is a related code, used in DVDs and Super Audio CDs (SACDs).
Kornelis Antonie "Kees" Schouhamer Immink is a Dutch engineer, inventor, and entrepreneur, who pioneered and advanced the era of digital audio, video, and data recording, including popular digital media such as compact disc (CD), DVD and Blu-ray disc. He has been a prolific and influential engineer, who holds more than 1100 U.S. and international patents. A large portion of the commonly used audio and video playback and recording devices use technologies based on his work. His contributions to coding systems assisted the digital video and audio revolution, by enabling reliable data storage at information densities previously unattainable.
Discman was Sony's brand name for portable CD players. The first Discman, the Sony D-50 or D-5, was launched in 1984. The brand name changed to CD Walkman, initially for Japanese lineups launched between October 1997 and March 1998, and then entirely in 2000. Discman and CD Walkman players are no longer produced.
In the compact disc system, cross-interleaved Reed–Solomon code (CIRC) provides error detection and error correction. CIRC adds to every three data bytes one redundant parity byte.
In digital audio using pulse-code modulation (PCM), bit depth is the number of bits of information in each sample, and it directly corresponds to the resolution of each sample. Examples of bit depth include Compact Disc Digital Audio, which uses 16 bits per sample, and DVD-Audio and Blu-ray Disc, which can support up to 24 bits per sample.
A CD-ROM is a type of read-only memory consisting of a pre-pressed optical compact disc that contains data. Computers can read—but not write or erase—CD-ROMs. Some CDs, called enhanced CDs, hold both computer data and audio with the latter capable of being played on a CD player, while data is only usable on a computer.
The history of optical recording can be divided into a few number of distinct major contributions. The pioneers of optical recording worked mostly independently, and their solutions to the many technical challenges have very distinctive features, such as
Toshitada Doi is a Japanese electrical engineer, who played a significant role in the digital audio revolution. He received a degree in electrical engineering from the Tokyo Institute of Technology in 1964, and a PhD from Tohoku University in 1972.
The Philips Natuurkundig Laboratorium or NatLab was the Dutch section of the Philips research department, which did research for the product divisions of that company.
