Compact Disc
Media type	Optical disc
Encoding	Various
Capacity	Typically up to 700 MB (up to 80 minutes audio)
Read mechanism	780 nm wavelength semiconductor laser
Developed by	Philips & Sony
Usage	Audio and data storage

A Compact Disc (or CD) is an optical disc used to store digital data, originally developed for storing digital audio. Mifu01jpg|200px|thumb|right|Chinese calligraphy written in a language content format by Song Dynasty (A A megabyte is a unit of Information or Computer storage equal to either 106 (1000000 Bytes or 220 (1048576 bytes depending on Koninklijke Philips Electronics NV ( Royal Philips Electronics Inc. is a multinational conglomerate corporation headquartered in Minato Tokyo, Japan, and one of the world's largest Media conglomerates with Optical disc authoring, including DVD and Blu-ray Disc authoring (often referred to colloquially but improperly as burning) is the process of assembling In Computing, an optical disc drive ( ODD) is a Disk drive that uses Laser light or electromagnetic waves near the Light spectrum Optical disc authoring, including DVD and Blu-ray Disc authoring (often referred to colloquially but improperly as burning) is the process of assembling Optical disc authoring software is Computer software for authoring optical discs including CD-ROMs and DVDs They are also known by synonyms Optical disc authoring requires a number of different technologies working in tandem from the media to the firmware to the control electronics of the drive. In Optical disc authoring, there are multiple modes for recording including Disc-At-Once, Track-At-Once, and Session-At-Once. Packet writing is an Optical disc recording technology used to allow write-once and rewritable CD and DVD media to be used in a similar manner to a The Laserdisc (LD is an obsolete Home video disc format and was the first commercial Optical disc storage medium Video Single Disc (abbreviated as VSD was a disc-based format that carried the same analog video information as a Laserdisc, but on a 12-centimetre (4 Red Book is the standard for audio CDs ( Compact Disc Digital Audio system or CDDA) The DTS-CD, DTS Audio CD or 51 Music Disc (official name is an audio Compact Disc that contains music in Surround sound format Super Audio CD ( SACD) is a read-only optical audio disc format that can provide higher fidelity digital audio reproduction than the Red Photo CD is a system designed by Kodak for digitizing and storing photos in a CD A CD-R ( C ompact D isc- R ecordable is a variation of the Compact Disc invented by Philips and Sony. CD-ROM (an initialism of "Compact Disc Read-Only Memory " is a pre-pressed Compact Disc that contains data accessible to but not writable Compact Disc ReWritable (CD-RW is a rewritable Optical disc format This article is about 'CD Video' a hybrid analog/digital format Super Video CD ( Super Video Compact Disc or SVCD) is a Digital format for storing Video on standard Compact discs SVCD was intended A CD+G (also known as CD+Graphics) is a special audio Compact disc that contains Graphics Data in addition to the audio data CD-Text is an extension of the Red Book Compact Disc specifications standard for Audio CDs It allows for storage of additional information (e CD-ROM XA is an extension of the Yellow Book Mode 2 standard for CD-ROMs that combines compressed audio visual and computer data allowing all to be accessed CD-i or Compact Disc Interactive is the name of an interactive multimedia CD player developed and marketed by Royal Philips Electronics N A MiniDisc ( MD) is a Magneto-optical disc-based Data storage device initially intended for storage of up to 80 minutes of digitized audio In January 2004 Sony announced the Hi-MD media storage format as a further development of the MiniDisc-Format. DVD (also known as " Digital Versatile Disc " or " Digital Video Disc " - see Etymology)is DVD-R is a DVD recordable format A DVD-R typically has a storage capacity of 4 A DVD+R is a once-writable Optical disc with 47 GB (4377 GiB) of storage capacity (more precisely 2295104 sectors of 2048 Bytes DVD-R DL (DL stands for Dual Layer) also called DVD-R9, is a derivative of the DVD-R format standard DVD+R DL (DL stands for Double Layer) also called DVD+R9, is a derivative of the DVD+R format created by the DVD+RW Alliance. A DVD-RW disc is a rewritable Optical disc with equal storage capacity to a DVD-R, typically 4 DVD+RW is the name of a standard for Optical discs one of several types of DVD, which hold up to about 4 DVD-RW DL is a rewritable Optical disc standard with storage capacity of 8 A DVD+RW DL is a rewritable Optical disc with storage capacity of 8 DVD-RAM ( DVD – Random Access Memory) is a disc specification presented in 1996 by the DVD Forum, which specifies rewritable DVD-RAM media and the appropriate DVD-Ds, also referred to as disposable DVDs are a type of digital video disc that is designed to be used for a maximum 48 hours after the containing package is opened Ultra Density Optical ( UDO) is an Optical disc format designed for high-density storage of high-definition video and The Universal Media Disc ( UMD) is an Optical disc medium developed by Sony for use on the PlayStation Portable. not insert the publicly disclosed HD DVD key into this article for the time being not insert the publicly disclosed HD DVD key into this article for the time being not insert the publicly disclosed HD DVD key into this article for the time being not insert the publicly disclosed HD DVD key into this article for the time being not insert the publicly disclosed HD DVD key into this article for the time being Blu-ray Disc recordable (or BD-R) refers to two Optical disc formats that can be recorded with an Optical disc recorder. For the series of US government publications on Computer security standards see Rainbow Series. ISO 9660 a standard published by the International Organization for Standardization (ISO defines a File system for CD-ROM media Joliet is the name of an extension to the ISO 9660 File system. The Rock Ridge Interchange Protocol (RRIP IEEE P1282 is an extension to the ISO 9660 volume format which adds POSIX File system semantics The El Torito Bootable CD Specification is an extension to the ISO 9660 CD-ROM specification The primary file system for Apple Macintosh computers is HFS (or HFS+ The Universal Disk Format ( UDF) is a format specification of a File system for storing files on optical media Mount Rainier ( MRW) is a format for writable Optical discs which provides the Packet writing and defect management Although research into Optical data storage has been ongoing for many decades the first popular system was the Compact Disc, introduced in 1982, adapted to data The CD, available on the market since late 1982, remains the standard playback medium for commercial audio recordings to the present day.

Standard CDs have a diameter of 120 mm and can hold up to 80 minutes of audio. There is also the Mini CD, with diameters ranging from 60 to 80 mm; they are sometimes used for CD singles, storing up to 24 minutes of audio. Not to be confused with MiniDisc. Mini CD s or "Pocket" CDs are Compact discs with a smaller Form factor

The technology was later adapted and expanded to include data storage (CD-ROM), write-once audio and data storage (CD-R), rewritable media (CD-RW), Super Audio CD (SACD), Video Compact Discs (VCD), Super Video Compact Discs (SVCD), PhotoCD, PictureCD, CD-i, and Enhanced CD. CD-ROM (an initialism of "Compact Disc Read-Only Memory " is a pre-pressed Compact Disc that contains data accessible to but not writable A CD-R ( C ompact D isc- R ecordable is a variation of the Compact Disc invented by Philips and Sony. Compact Disc ReWritable (CD-RW is a rewritable Optical disc format Super Audio CD ( SACD) is a read-only optical audio disc format that can provide higher fidelity digital audio reproduction than the Red Super Video CD ( Super Video Compact Disc or SVCD) is a Digital format for storing Video on standard Compact discs SVCD was intended CD-ROMs and CD-Rs remain widely used technologies in the computer industry. The CD and its extensions have been extremely successful: in 2004, worldwide sales of CD audio, CD-ROM, and CD-R reached about 30 billion discs. ^[1] By 2007, 200 billion CDs had been sold worldwide.

History

The compact disc is a successful spin-off of the much less successful Laserdisc technology. The Laserdisc (LD is an obsolete Home video disc format and was the first commercial Optical disc storage medium In 1979, Sony and Philips Consumer Electronics set up a joint task force of engineers to design a new digital audio disc. is a multinational conglomerate corporation headquartered in Minato Tokyo, Japan, and one of the world's largest Media conglomerates with Philips Consumer Electronics is a part of Koninklijke Philips Electronics N The task force, led by prominent members Kees Immink and Toshitada Doi (土井利忠), progressed the research into laser technology and optical discs that had been started by Philips in 1977. Kornelis Antonie (Kees Schouhamer Immink (born 18 December, 1946 in Rotterdam) is a Dutch scientist inventor and entrepreneur who pioneered ^[2] After a year of experimentation and discussion, the taskforce produced the Red Book, the Compact Disc standard. Red Book is the standard for audio CDs ( Compact Disc Digital Audio system or CDDA) Philips contributed the general manufacturing process, based on video LaserDisc technology. Manufacturing (from Latin manu factura, "making by hand" is the use of tools and labor to make things for use or sale Industrial processes are procedures involving chemical or mechanical steps to aid in the Manufacture of an item or items usually carried out on a very The Laserdisc (LD is an obsolete Home video disc format and was the first commercial Optical disc storage medium Philips also contributed Eight-to-Fourteen Modulation (EFM), which offers both a long playing time and a high resilience against disc defects such as scratches and fingerprints, while Sony contributed the error-correction method, CIRC. Eight-to-Fourteen Modulation ( EFM) is a data encoding technique used by CDs and pre- Hi-MD MiniDiscs EFM and EFMPlus were both invented In Mathematics, Computer science, Telecommunication, and Information theory, error detection and correction has great practical importance in In the Compact disc system Error correction and detection is provided by cross-interleaved Reed-Solomon code. The Compact Disc Story,^[3] told by a former member of the taskforce, gives background information on the many technical decisions made, including the choice of the sampling frequency, playing time, and disc diameter. According to Philips, the Compact Disc was thus "invented collectively by a large group of people working as a team. "^[4]

The first CD that was pressed in Hanover was a recording of Herbert von Karajan conducting the Alpine Symphony by Richard Strauss^[5]. In August 1982 the real pressing was ready to begin in the new factory, not far from the place where Emil Berliner had produced his first gramophone record 93 years earlier. (Deutsche Grammophon, Berliner’s company, had by now become a part of PolyGram). CDs and Sony's CD player CDP-101 reached the market on October 1, 1982 in Japan, and early the following year in the United States and other markets. is a multinational conglomerate corporation headquartered in Minato Tokyo, Japan, and one of the world's largest Media conglomerates with A Compact Disc player (often written as compact disc player) or CD player, is an electronic device which plays audio Compact Discs CD players are often Events 331 BC - Alexander the Great defeats Darius III of Persia in the Battle of Gaugamela. Year 1982 ( MCMLXXXII) was a Common year starting on Friday (link displays the 1982 Gregorian calendar) For a topic outline on this subject see List of basic Japan topics. The United States of America —commonly referred to as the This event is often seen as the "Big Bang" of the digital audio revolution. The Big Bang is the cosmological model of the Universe that is best supported by all lines of scientific evidence and Observation. The new audio disc was enthusiastically received, especially in the early-adopting classical music and audiophile communities and its handling quality received particular praise. Classical music is a broad term that usually refers to mainstream music produced in or rooted in the traditions of Western liturgical and Secular music An audiophile, from Latin audio "I hear" and Greek philos "loving" is an audio reproduction enthusiast who typically listens As the price of players sank rapidly, the CD began to gain popularity in the larger popular and rock music markets. Popular music is Music belonging to any of a number of musical styles that are accessible to the general public and are disseminated by one or more Rock music is a genre of Popular music often though not necessarily employing Electric guitar, Bass guitar, and Drums. The first artist to sell a million copies on CD was Dire Straits, with their 1985 album Brothers in Arms. Dire Straits was a British rock band, formed in 1977 by Mark Knopfler (guitar and vocals his brother David Knopfler (guitar Brothers in Arms is the fifth Studio album by British rock band Dire Straits, in 1985. ^[6] In 1986 Queen became the first artist to have their entire catalogue converted to the format. Queen were an English rock band formed in 1970 in London by guitarist ^[7]

The CD was originally thought of as an evolution of the gramophone record, rather than primarily as a data storage medium. A gramophone Only later did the concept of an "audio file" arise, and the generalising of this to any data file. From its origins as a music format, Compact Disc has grown to encompass other applications. In June 1985, the CD-ROM (read-only memory) and, in 1990, CD-Recordable were introduced, also developed by Sony and Philips. CD-ROM (an initialism of "Compact Disc Read-Only Memory " is a pre-pressed Compact Disc that contains data accessible to but not writable A CD-R ( C ompact D isc- R ecordable is a variation of the Compact Disc invented by Philips and Sony. is a multinational conglomerate corporation headquartered in Minato Tokyo, Japan, and one of the world's largest Media conglomerates with Koninklijke Philips Electronics NV ( Royal Philips Electronics Inc.

Physical details

The optical lens of a CD drive.

A Compact Disc is made from a 1. 2 mm thick disc of almost pure polycarbonate plastic and weighs approximately 16 grams. Plastic is the general common term for a wide range of synthetic or semisynthetic organic solid materials suitable for the manufacture of industrial products A thin layer of aluminium or, more rarely, gold is applied to the surface to make it reflective, and is protected by a film of lacquer. WikipediaNaming A gold CD is one in which Gold is used in place of the super purity Aluminium commonly used as the reflective coating on ordinary CDs The gold coats In a general sense lacquer is a clear or coloured Varnish, that dries by solvent evaporation and often a curing process as well that produces a hard durable finish in any The lacquer is normally spin coated directly on top of the reflective layer. On top of that surface, the label print is applied. A label is a piece of Paper, Polymer, Cloth, Metal, or other material affixed to a container or article on which is Printed Common printing methods for CDs are screen-printing and offset printing. Screen printing is a printing technique that uses a woven mesh to support an ink blocking stencil Offset printing is a commonly used Printing technique where the Inked image is transferred (or "offset" from a plate to a rubber blanket then to the

CD data is stored as a series of tiny indentations (pits), encoded in a tightly packed spiral track molded into the top of the polycarbonate layer. The areas between pits are known as "lands". Each pit is approximately 100 nm deep by 500 nm wide, and varies from 850 nm to 3. A nanometre ( American spelling: nanometer, symbol nm) ( Greek: νάνος nanos dwarf; μετρώ metrό count) is a 5 µm in length. A micrometre ( American spelling: micrometer; symbol µm) is one millionth of a Metre, or equivalently one thousandth of a Millimetre

The spacing between the tracks, the pitch, is 1. 6 µm. A CD is read by focusing a 780 nm wavelength (near infrared) semiconductor laser through the bottom of the polycarbonate layer. In Physics wavelength is the distance between repeating units of a propagating Wave of a given Frequency. Infrared ( IR) radiation is Electromagnetic radiation whose Wavelength is longer than that of Visible light, but shorter than that of A laser diode is a Laser where the active medium is a Semiconductor similar to that found in a Light-emitting diode. The change in height between pits and lands results in a difference in intensity in the light reflected. By measuring the intensity change with a photodiode, the data can be read from the disc. A photodiode is a type of Photodetector capable of converting Light into either current or Voltage, depending upon the mode of operation

The pits and lands themselves do not directly represent the zeros and ones of binary data. Instead, Non-return-to-zero, inverted (NRZI) encoding is used: a change from pit to land or land to pit indicates a one, while no change indicates a zero. In Telecommunication, a non-return-to-zero ( NRZ) Line code is a binary code in which "1s" are represented by one Significant This in turn is decoded by reversing the Eight-to-Fourteen Modulation used in mastering the disc, and then reversing the Cross-Interleaved Reed-Solomon Coding, finally revealing the raw data stored on the disc. In the Compact disc system Error correction and detection is provided by cross-interleaved Reed-Solomon code.

While CDs are significantly more durable than earlier audio formats, they are susceptible to damage from daily usage and environmental factors. Pits are much closer to the label side of a disc, so that defects and dirt on the clear side can be out of focus during playback. Discs consequently suffer more damage because of defects such as scratches on the label side, whereas clear-side scratches can be repaired by refilling them with plastic of similar index of refraction, or by careful polishing. The refractive index (or index of Refraction) of a medium is a measure for how much the speed of light (or other waves such as sound waves is reduced inside the medium Early music CDs were known to suffer from "CD rot" or "laser rot" where the internal reflective layer itself degrades. CD rot (or DVD rot) is a phrase describing the tendency of CD or DVD disks to become unreadable due to physical or chemical deterioration When this occurs the CD may become unplayable.

Disc shapes and diameters

A Mini-CD is 8 centimeters in diameter.

The digital data on a CD begins at the center of the disc and proceeds outwards to the edge, which allows adaptation to the different size formats available. Standard CDs are available in two sizes. By far the most common is 120 mm in diameter, with a 74 or 80-minute audio capacity and a 650 or 700 MB data capacity. Geometry, a diameter of a Circle is any straight Line segment that passes through the center of the circle and whose Endpoints are on the This diameter has also been adopted by later formats, including Super Audio CD, DVD, HD DVD, and Blu-ray. Super Audio CD ( SACD) is a read-only optical audio disc format that can provide higher fidelity digital audio reproduction than the Red DVD (also known as " Digital Versatile Disc " or " Digital Video Disc " - see Etymology)is not insert the publicly disclosed HD DVD key into this article for the time being 80 mm discs ("Mini CDs") were originally designed for CD singles and can hold up to 21 minutes of music or 184 MB of data but never really became popular. Not to be confused with MiniDisc. Mini CD s or "Pocket" CDs are Compact discs with a smaller Form factor Today nearly all singles are released on 120 mm CDs, which is called a Maxi single. A maxi single or maxi-single is a music single release with more than the usual two tracks (generally an a-side song and a b-side song

"Shaped CD"

Novelty shaped CDs are also available in a number of shapes and sizes, and are mostly used for marketing. A shaped CD is a non-circular Compact disc. Examples include CDs in the shape of a business card a star a map of a country and more A common variant is a "business card" CD, a CD-single with portions removed at the top and bottom to more closely resemble the form-factor of a business card. Business cards are Cards bearing business Information about a Company or Individual.

Logical formats

Audio CD

Main article: Red Book (audio CD standard)

The logical format of an audio CD (officially Compact Disc Digital Audio or CD-DA) is described in a document produced in 1980 by the format's joint creators, Sony and Philips. Red Book is the standard for audio CDs ( Compact Disc Digital Audio system or CDDA) is a multinational conglomerate corporation headquartered in Minato Tokyo, Japan, and one of the world's largest Media conglomerates with Koninklijke Philips Electronics NV ( Royal Philips Electronics Inc. The document is known colloquially as the "Red Book" after the color of its cover. Red Book is the standard for audio CDs ( Compact Disc Digital Audio system or CDDA) The format is a two-channel 16-bit PCM encoding at a 44. 1 kHz sampling rate per channel. Sampling theorem The Nyquist–Shannon sampling theorem states that perfect reconstruction Four-channel sound is an allowed option within the Red Book format, but has never been implemented. Monaural audio has no existing standard on a Red Book CD; mono source material is usually presented as two identical channels on a 'stereo' track. Monaural (often shortened to mono) sound reproduction is single-channel

The selection of the sample rate was primarily based on the need to reproduce the audible frequency range of 20 Hz - 20 kHz. The Nyquist–Shannon sampling theorem states that a sampling rate of double the maximum frequency to be recorded is needed, resulting in a 40 kHz rate. The Nyquist–Shannon sampling theorem is a fundamental result in the field of Information theory, in particular Telecommunications and Signal processing The exact sampling rate of 44. 1 kHz was inherited from a method of converting digital audio into an analog video signal for storage on U-matic video tape, which was the most affordable way to transfer data from the recording studio to the CD manufacturer at the time the CD specification was being developed. U-matic is the name of a Videocassette The device that turns an analog audio signal into PCM audio, which in turn is changed into an analog video signal is called a PCM adaptor. A PCM adaptor is a device used for recording Digital audio in the PCM format which in turn connects to a Video cassette recorder (acting as a transport This technology could store six samples (three samples per each stereo channel) in a single horizontal line. Stereophonic sound, commonly called stereo, is the reproduction of Sound, using two or more independent audio channels through a Symmetrical A standard NTSC video signal has 245 usable lines per field, and 59. NTSC ( National Television System Committee) is the Analog television system used in the United States, Canada, Japan, Mexico 94 fields/s, which works out at 44,056 samples/s/stereo channel. Similarly, PAL has 294 lines and 50 fields, which gives 44,100 samples/s/stereo channel. PAL, short for Phase Alternating Line, is a colour -encoding system used in Broadcast television systems in large parts of the world This system could either store 14-bit samples with some error correction, or 16-bit samples with almost no error correction.

There was a long debate over whether to use 14 bit (Philips) or 16-bit (Sony) quantization, and 44,056 or 44,100 samples/s (Sony) or around 44,000 samples/s (Philips). When the Sony/Philips task force designed the Compact Disc, Philips had already developed a 14-bit D/A converter, but Sony insisted on 16 bit. In Electronics, a digital-to-analog converter ( DAC or D-to-A) is a device for converting a digital (usually binary code to an Analog signal In the end, 16 bits and 44. 1 kilosamples per second prevailed. Philips found a way to produce 16-bit quality using their 14-bit DAC by using four times oversampling. In Signal processing, oversampling is the process of sampling a signal with a Sampling frequency significantly higher than twice the bandwidth

Storage capacity and playing time

The partners aimed at a playing time of 60 minutes with a disc diameter of 100 mm (Sony) or 115 mm (Philips). ^[8] Sony vice-president Norio Ohga suggested extending the capacity to 74 minutes to accommodate Wilhelm Furtwängler's 1951 performance of Beethoven’s 9th Symphony at the Bayreuth Festival. is a multinational conglomerate corporation headquartered in Minato Tokyo, Japan, and one of the world's largest Media conglomerates with is a Japanese electronics businessman who originally trained as an opera singer WikipediaWikiProject Classical music#Biographical_infoboxes --> Wilhelm Furtwängler (January 25 1886 &ndash November 30 1954 was a The Symphony No 9 in D minor Op 125 "Choral" is the last complete Symphony composed by Ludwig van Beethoven. The Bayreuth Festival is a music festival held annually in Bayreuth, Germany, at which performances of Operas by the 19th century German composer ^[9]

The extra 14 minute playing time subsequently required changing to a 120 mm disc. Kees Immink, Philips' chief engineer, however, denies this, claiming that the increase was motivated by technical considerations, and that even after the increase in size, the Furtwängler recording was not able to fit onto the earliest CDs. ^[3][8] According to a Sunday Tribune interview,^[10] the story is slightly more involved. The Sunday Tribune is an Irish Sunday Broadsheet Newspaper published by Tribune Newspapers plc At that time (1979) Philips owned Polygram, one of the world’s largest distributors of music. PolyGram was the name from 1972 of the Major label recording company started by Philips as a holding company for its music interests in 1945 Polygram had set up a large experimental CD plant in Hanover, Germany, which could produce huge numbers of CDs having, of course, a diameter of 115 mm. Hanover (i ( haˈnoːfɐ on the river Leine, is the capital of the federal state of Lower Saxony ( Niedersachsen Germany, officially the Federal Republic of Germany ( ˈbʊndəsʁepuˌbliːk ˈdɔʏtʃlant is a Country in Central Europe. Sony did not yet have such a facility. If Sony had agreed on the 115 mm disc, Philips would have had a significant competitive edge in the market. Sony decided that something had to be done. The long playing time of Beethoven's Ninth imposed by Ohga was used to push Philips to accept 120 mm, so that Philips’ Polygram lost its edge on disc fabrication. ^[10]

The 74-minute playing time of a CD, which was much longer than the 15 to 20 minutes per side possible with long-playing vinyl albums, 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 tracks, enticing consumers to buy the CD for the extra material. However, attempts to combine double LPs onto one CD occasionally resulted in an opposing situation in which the CD would actually offer fewer tracks than the LP equivalent. An example is the 1987 album Kiss Me, Kiss Me, Kiss Me by The Cure, which states in the CD liner notes: "The track Hey You!!! which appears on the double album and cassette has been omitted so as to facilitate a single compact disc. Kiss Me Kiss Me Kiss Me is the seventh studio Album by British Alternative rock band The Cure. The Cure are an English rock band that formed in Crawley, West Sussex in 1976 " The 2006 re-release of this album saw the re-inclusion of the missing track. ^[11] Another example is the original late-1980s Warner Bros. Records reissue of Fleetwood Mac's Tusk album, which substituted the long album version of "Sara" with the shorter single version. Warner Bros Records Inc is an American Record label that operates as a wholly owned Subsidiary of Warner Music Group. Fleetwood Mac are a British / American Tusk is a Double album released in 1979 (see 1979 in music) by Fleetwood Mac. Enough complaints were lodged to eventually convince Warner Bros. to remaster the album in the mid-1990s with the original contents intact. ^[12]

Main physical parameters

The main parameters of the CD (taken from the September 1983 issue of the audio CD specification) are as follows:

• Scanning velocity: 1. Red Book is the standard for audio CDs ( Compact Disc Digital Audio system or CDDA) 2–1. 4 m/s (constant linear velocity) – equivalent to approximately 500 rpm at the inside of the disc, and approximately 200 rpm at the outside edge. In Optical storage, constant linear velocity (CLV is a qualifier for the rated speed of an Optical disc drive, and may also be applied to the writing speed of recordable (A disc played from beginning to end slows down during playback. )
• Track pitch: 1. 6 µm
• Disc diameter 120 mm
• Disc thickness: 1. 2 mm
• Inner radius program area: 25 mm
• Outer radius program area: 58 mm
• Center spindle hole diameter: 15 mm

The program area is 86. 05 cm² and the length of the recordable spiral is (86. 05 cm² / 1. 6 µm) = 5. 38 km. With a scanning speed of 1. 2 m/s, the playing time is 74 minutes, or around 650 MB of data on a CD-ROM. If the disc diameter were only 115 mm, the maximum playing time would have been 68 minutes, i. e. , six minutes less. A disc with data packed slightly more densely is tolerated by most players (though some old ones fail). Using a linear velocity of 1. 2 m/s and a track pitch of 1. 5 µm leads to a playing time of 80 minutes, or a capacity of 700 MB. Even higher capacities on non-standard discs (up to 99 minutes) are available at least as recordables, but generally the tighter the tracks are squeezed the worse the compatibility.

Data structure

The smallest entity in a CD is called a frame. A frame consists of 33 bytes and contains six complete 16-bit stereo samples (2 bytes × 2 channels × six samples: equals 24 bytes). The other nine bytes consist of eight Cross-Interleaved Reed-Solomon Coding error correction bytes and one subcode byte, used for control and display. In the Compact disc system Error correction and detection is provided by cross-interleaved Reed-Solomon code. Besides digital audio a Compact disc contains digital data called subcode or subchannel data, which is multiplexed with the digital audio Each byte is translated into a 14-bit word using Eight-to-Fourteen Modulation, which alternates with 3-bit merging words. Eight-to-Fourteen Modulation ( EFM) is a data encoding technique used by CDs and pre- Hi-MD MiniDiscs EFM and EFMPlus were both invented In total there are 33 × (14 + 3) = 561 bits. A 27-bit unique synchronization word is added, so that the number of bits in a frame totals 588 (of which only 192 bits are music).

These 588-bit frames are in turn grouped into sectors. Each sector contains 98 frames, totaling 98 × 24 = 2352 bytes of music. The CD is played at a speed of 75 sectors per second, which results in 176,400 bytes per second. Divided by 2 channels and 2 bytes per sample, this results in a sample rate of 44,100 samples per second.

For CD-ROM data discs, the physical frame and sector sizes are the same. Since error concealment cannot be applied to non-audio data in case the CIRC error correction fails to recover the user data, a third layer of error correction is defined, reducing the payload to 2048 bytes per sector for the Mode-1 CD-ROM format. To increase the data-rate for Video CD, Mode-2 CD-ROM, the third layer has been omitted, increasing the payload to 2336 user-available bytes per sector, only 16 bytes (for synchronization and header data) less than available in Red-Book audio.

"Frame"

For the Red Book stereo audio CD, the time format is commonly measured in minutes, seconds and frames (mm:ss:ff), where one frame corresponds to one sector, or 1/75th of a second of stereo sound. Note that in this context, the term frame is erroneously applied in editing applications and does not denote the physical frame described above. In editing and extracting, the frame is the smallest addressable time interval for an audio CD, meaning that track start and end positions can only be defined in 1/75 second steps.

Logical structure

The largest entity on a CD is called a track. A CD can contain up to 99 tracks (including a data track for mixed mode discs). A Mixed Mode CD is a Compact disc in which two different data types are combined Each track can in turn have up to 100 indexes, though players which handle this feature are rarely found outside of pro audio, particularly radio broadcasting. Professional audio, also 'pro audio' can be used a term to refer to both a type of audio equipment as well as a type of audio engineering application Radio is the transmission of signals by Modulation of electromagnetic waves with frequencies below those of visible Light. For the band see Broadcast (band Broadcasting is the distribution of audio and/or Video signals which transmit The vast majority of songs are recorded under index 1, with the pre-gap being index 0. The pregap on a Red Book audio CD is the portion of the audio track that precedes "index 01" for a given track in the table of contents (TOC Sometimes hidden tracks are placed at the end of the last track of the disc, often using index 2 or 3. In the field of recorded music, a hidden track (sometimes secret track) is a piece of music which has been placed on a Compact disc, audio cassette This is also the case with some discs offering "101 sound effects", with 100 and 101 being index 2 and 3 on track 99. For the album by The Jam see Sound Affects. Sound effects or audio effects are artificially created or enhanced Sounds The index, if used, is occasionally put on the track listing as a decimal part of the track number, such as 99. The decimal ( base ten or occasionally denary) Numeral system has ten as its base. 2 or 99. 3. (Information Society's Hack was one of very few CD releases to do this, following a release with an equally-obscure CD+G feature. Information Society (also known as InSoc) is a US band originally from Minneapolis, Minnesota, primarily consisting of Kurt Hack is an album by Latin freestyle Synth-pop band Information Society. ) The track and index structure of the CD carried forward to the DVD as title and chapter, respectively.

Manufacturing tolerances

Current manufacturing processes allow an audio CD to contain up to 80 minutes (variable from one replication plant to another) without requiring the content creator to sign a waiver. A waiver is the voluntary relinquishment or Surrender of some known Right or Privilege. Thus, in current practice, maximum CD playing time has crept higher by reducing minimum engineering tolerances, while still maintaining acceptable standards of reliability. Engineering tolerance is the permissible limit of variation in a physical Dimension, a measured value or Physical property of a

CD-Text

Main article: CD-Text

CD-Text is an extension of the Red Book specification for audio CD that allows for storage of additional text information (e. CD-Text is an extension of the Red Book Compact Disc specifications standard for Audio CDs It allows for storage of additional information (e Red Book is the standard for audio CDs ( Compact Disc Digital Audio system or CDDA) g. , album name, song name, artist) on a standards-compliant audio CD. The information is stored either in the lead-in area of the CD, where there is roughly five kilobytes of space available, or in the subcode channels R to W on the disc, which can store about 31 megabytes. Optical disc authoring, including DVD and Blu-ray Disc authoring (often referred to colloquially but improperly as burning) is the process of assembling Besides digital audio a Compact disc contains digital data called subcode or subchannel data, which is multiplexed with the digital audio

CD + Graphics

Main article: CD+G

Compact Disc + Graphics (CD+G) is a special audio compact disc that contains graphics data in addition to the audio data on the disc. A CD+G (also known as CD+Graphics) is a special audio Compact disc that contains Graphics Data in addition to the audio data Sound' is Vibration transmitted through a Solid, Liquid, or Gas; particularly sound means those vibrations composed of Frequencies Graphics (from Greek grc [[wiktγραφικός γραφικός]] see -graphy) are Visual presentations on some surface such as a wall Debt AIDS Trade in Africa (or DATA) is a Multinational non-government organization founded in January 2002 in London by U2 's The disc can be played on a regular audio CD player, but when played on a special CD+G player, can output a graphics signal (typically, the CD+G player is hooked up to a television set or a computer monitor); these graphics are almost exclusively used to display lyrics on a television set for karaoke performers to sing along with. Television ( TV) is a widely used Telecommunication medium for sending ( Broadcasting) and receiving moving Images, either monochromatic A visual display unit, often called simply a monitor or display, is a piece of Electrical equipment which displays images generated from the Video Lyrics (in singular form Lyric) are a set of words that accompany music either by speaking or singing (kɑːrɑːˌoʊkɛ in Japanese karaoke) is a form of Entertainment in which Amateur Singers sing along with recorded Music (and/or a

CD + Extended Graphics

Main article: Compact Disc + Extended Graphics

Compact Disc + Extended Graphics (CD+EG, also known as CD+XG) is an improved variant of the Compact Disc + Graphics (CD+G) format. Compact Disc + Extended Graphics ( CD+EG, also known as CD+XG) is an improved variant of the Compact Disc + Graphics ( CD+G) format Like CD+G, CD+EG utilizes basic CD-ROM features to display text and video information in addition to the music being played. This extra data is stored in subcode channels R-W. Besides digital audio a Compact disc contains digital data called subcode or subchannel data, which is multiplexed with the digital audio Very few, if any, CD+EG discs have been published.

Super Audio CD

Main article: Super Audio CD

Super Audio CD (SACD) is a read-only optical audio disc format aimed at providing much higher fidelity digital audio reproduction than the Red Book audio CD. Super Audio CD ( SACD) is a read-only optical audio disc format that can provide higher fidelity digital audio reproduction than the Red High fidelity or hi-fi reproduction is a term used by home stereo listeners and home audio enthusiasts ( Audiophiles to refer to high-quality reproduction Red Book is the standard for audio CDs ( Compact Disc Digital Audio system or CDDA) Introduced in 1999, it was developed by Sony and Philips Electronics, the same companies that created the Red Book audio CD. is a multinational conglomerate corporation headquartered in Minato Tokyo, Japan, and one of the world's largest Media conglomerates with Koninklijke Philips Electronics NV ( Royal Philips Electronics Inc. Red Book is the standard for audio CDs ( Compact Disc Digital Audio system or CDDA) SACD was in a format war with DVD-Audio, but neither has yet managed to replace audio CDs. A format war describes competition between mutually incompatible proprietary formats typically for Data storage devices and Recording formats for Electronic DVD-Audio (commonly abbreviated as DVD-A) is a digital format for delivering very High-fidelity audio content on a DVD. SACD has the advantage over DVD-Audio in that most SACD discs are hybrids: they also contain a standard audio CD layer which is playable in existing CD players.

CD-MIDI

Compact Disc MIDI or CD-MIDI is a type of CD where MIDI format is used to store music performance data which upon playback is performed by electronic instruments that synthesize the audio that is heard. MIDI ( Musical Instrument Digital Interface, ˈmɪdi is an industry-standard protocol that enables Electronic musical instruments Computers Hence unlike Red Book audio CD, these recordings are not audio. Red Book is the standard for audio CDs ( Compact Disc Digital Audio system or CDDA)

CD-ROM

Main article: CD-ROM

For its first few years of existence, the Compact Disc was purely an audio format. CD-ROM (an initialism of "Compact Disc Read-Only Memory " is a pre-pressed Compact Disc that contains data accessible to but not writable However, in 1985 the Yellow Book CD-ROM standard was established by Sony and Philips, which defined a non-volatile optical data computer data storage medium using the same physical format as audio compact discs, readable by a computer with a CD-ROM drive. The Yellow Book is the Standard that defines the format of CD-ROMs The Yellow Book created by Sony and Philips, was the first extension of the is a multinational conglomerate corporation headquartered in Minato Tokyo, Japan, and one of the world's largest Media conglomerates with Koninklijke Philips Electronics NV ( Royal Philips Electronics Inc. Computer data storage, often called storage or memory, refers to Computer components devices and recording media that retain digital

Video CD

Main article: Video CD

Video CD (aka VCD, View CD, Compact Disc digital video) is a standard digital format for storing video on a Compact Disc. A digital system uses discrete (discontinuous values usually but not always Symbolized Numerically (hence called "digital" to represent information for Video is the technology of electronically capturing, Recording, processing storing transmitting and reconstructing a sequence of Still images VCDs are playable in dedicated VCD players, most modern DVD-Video players, personal computers, and some video game consoles. DVD-Video is a consumer video format used to store digital video on DVD (DVD-ROM discs and is currently the dominant form of consumer video formats in the United

The VCD standard was created in 1993 by Sony, Philips, Matsushita, and JVC and is referred to as the White Book standard. is a multinational conglomerate corporation headquartered in Minato Tokyo, Japan, and one of the world's largest Media conglomerates with Koninklijke Philips Electronics NV ( Royal Philips Electronics Inc. ( usually referred to as JVC, is an International consumer and professional electronics Corporation based in Yokohama, Japan which was founded The White Book, which was released in 1987 by Sony, Philips, Matsushita, and JVC refers to a standard of Compact disc that

Overall picture quality is intended to be comparable to VHS video. Poorly compressed VCD video can sometimes be lower quality than VHS video, but VCD exhibits block artifacts rather than analog noise, and does not deteriorate further with each use, which may be preferable.

352x240 (or SIF) resolution was chosen because it is half the vertical, and half the horizontal resolution of NTSC video. Source Input Format ( SIF) defined in MPEG-1, is a video format that was developed to allow the storage and transmission of digital video 352x288 is similarly one quarter PAL/SECAM resolution. This approximates the (overall) resolution of an analog VHS tape, which, although it has double the number of (vertical) scan lines, has a much lower horizontal resolution.

Super Video CD

Main article: Super Video CD

Super Video CD (Super Video Compact Disc or SVCD) is a format used for storing video on standard compact discs. Super Video CD ( Super Video Compact Disc or SVCD) is a Digital format for storing Video on standard Compact discs SVCD was intended Video is the technology of electronically capturing, Recording, processing storing transmitting and reconstructing a sequence of Still images SVCD was intended as a successor to Video CD and an alternative to DVD-Video, and falls somewhere between both in terms of technical capability and picture quality. DVD-Video is a consumer video format used to store digital video on DVD (DVD-ROM discs and is currently the dominant form of consumer video formats in the United

SVCD has two-thirds the resolution of DVD, and over 2. The display resolution of a Digital television or Computer display typically refers to the number of distinct pixels in each dimension that can be displayed DVD (also known as " Digital Versatile Disc " or " Digital Video Disc " - see Etymology)is 7 times the resolution of VCD. One CD-R disc can hold up to 60 minutes of standard quality SVCD-format video. While no specific limit on SVCD video length is mandated by the specification, one must lower the video bit rate, and therefore quality, in order to accommodate very long videos. It is usually difficult to fit much more than 100 minutes of video onto one SVCD without incurring significant quality loss, and many hardware players are unable to play video with an instantaneous bit rate lower than 300 to 600 kilobits per second. A kilobit is a unit of information abbreviated kbit (or kb) The standard definition is 1 kilobit = 103 bit = 1000 Bit.

Photo CD

Main article: Photo CD

Photo CD is a system designed by Kodak for digitizing and storing photos on a CD. Photo CD is a system designed by Kodak for digitizing and storing photos in a CD Eastman Kodak Company ( is an American multinational Public company which produces imaging and photographic materials and equipment Launched in 1992, the discs were designed to hold nearly 100 high quality images, scanned prints and slides using special proprietary encoding. Year 1992 ( MCMXCII) was a Leap year starting on Wednesday (link will display full 1992 Gregorian calendar) Photo CD discs are defined in the Beige Book and conform to the CD-ROM XA and CD-i Bridge specifications as well. For the series of US government publications on Computer security standards see Rainbow Series. CD-ROM (an initialism of "Compact Disc Read-Only Memory " is a pre-pressed Compact Disc that contains data accessible to but not writable They are intended to play on CD-i players, Photo CD players and any computer with the suitable software irrespective of the operating system. An operating system (commonly abbreviated OS and O/S) is the software component of a Computer system that is responsible for the management and coordination The images can also be printed out on photographic paper with a special Kodak machine.

Picture CD

Main article: Picture CD

Picture CD is another photo product by Kodak, following on from the earlier Photo CD product. Picture CD is a product by Kodak, following on from the earlier Photo CD product Eastman Kodak Company ( is an American multinational Public company which produces imaging and photographic materials and equipment It holds photos from a single roll of color film, stored at 1024×1536 resolution using JPEG compression. The product is aimed at consumers. Software to view and perform simple edits to images is included on the CD.

CD-i

Main article: Green Book (CD-interactive standard)

The Philips "Green Book" specifies the standard for interactive multimedia compact discs designed for CD-i players. The Philips "Green Book" specifies the standard for interactive multimedia Compact discs designed for CD-i players CD-i or Compact Disc Interactive is the name of an interactive multimedia CD player developed and marketed by Royal Philips Electronics N This format is unusual because it hides the initial tracks which contains the software and data files used by CD-i players by omitting the tracks from the disc's TOC (table of contents). This causes audio CD players to skip the CD-i data tracks. Red Book is the standard for audio CDs ( Compact Disc Digital Audio system or CDDA) This is different from the CD-i Ready format, which puts CD-i software and data into the pregap of track 1. CD-i Ready is a Compact disc format based on the CD-i format CD-i format and CD-i Ready format use different techniques to get audio CD players to skip The pregap on a Red Book audio CD is the portion of the audio track that precedes "index 01" for a given track in the table of contents (TOC

Enhanced CD

Main article: Enhanced CD

Enhanced CD, also known as CD Extra and CD Plus, is a certification mark of the Recording Industry Association of America for various technologies that combine audio and computer data for use in both compact disc and CD-ROM players. Enhanced CD, also known as CD Extra and CD Plus, is a Certification mark of the Recording Industry Association of America for various technologies A certification mark on a commercial product indicates five things The existence of a legal follow-up or Product certification agreement between the manufacturer CD-ROM (an initialism of "Compact Disc Read-Only Memory " is a pre-pressed Compact Disc that contains data accessible to but not writable

The primary data formats for Enhanced CD disks are mixed mode (Yellow Book/Red Book), CD-i, hidden track, and multisession (Blue Book). A Mixed Mode CD is a Compact disc in which two different data types are combined The Yellow Book is the Standard that defines the format of CD-ROMs The Yellow Book created by Sony and Philips, was the first extension of the Red Book is the standard for audio CDs ( Compact Disc Digital Audio system or CDDA) CD-i or Compact Disc Interactive is the name of an interactive multimedia CD player developed and marketed by Royal Philips Electronics N The Blue Book or Enhanced Music CD specification describes the Enhanced Music CD disc format

Manufacture

Main article: CD manufacturing

Replicated CDs are mass-produced initially using a hydraulic press. Compact disc manufacturing is the process by which commercial Compact discs (CDs are replicated in mass quantities using a master version created from a source recording Small granules of raw polycarbonate plastic are fed into the press while under heat. A screw forces the liquified plastic into the mold cavity. The mold closes with a metal stamper in contact with the disc surface. The plastic is allowed to cool and harden. Once opened, the disc substrate is removed from the mold by a robotic arm, and a 15 mm diameter center hole (called a stacking ring) is removed. The cycle time, the time it takes to "stamp" one CD, is usually 2–3 seconds.

This method produces the clear plastic blank part of the disc. After the metallic layer is applied to the clear blank substrate, the disc goes under a UV light for drying and it is ready to go to press. To press the CD, first a glass master is cut using a high-power laser on a device similar to a CD writer. This glass master is a positive master. After testing, it is used to make a die by pressing it against a metal disc. A die is a specialized Tool used in Manufacturing industries to cut shape and form a wide variety of products and components

The die then becomes a negative image: a number of them can be made depending on the number of pressing mills that are to be running off copies of the final CD. The die then goes into the press and the image is pressed onto the blank CD, leaving a final positive image on the disc. A small circle of lacquer is then applied as a ring around the center of the disc, and a fast spin spreads it evenly over the surface. The disc can then be printed and packed.

Manufactured CDs that are sold in stores are wrapped/sealed via a process called "polywrapping" or are shrink wrapped. Polywrapping is an automated process of wrapping an item in a clear or printed Polythene film "Shrinkwrapped" redirects here For the album see Shrinkwrapped (album.

Recordable CD

700 MB CD-R

Main article: CD-R

Recordable compact discs, CD-Rs, are injection molded with a "blank" data spiral. A megabyte is a unit of Information or Computer storage equal to either 106 (1000000 Bytes or 220 (1048576 bytes depending on A CD-R ( C ompact D isc- R ecordable is a variation of the Compact Disc invented by Philips and Sony. A CD-R ( C ompact D isc- R ecordable is a variation of the Compact Disc invented by Philips and Sony. A photosensitive dye is then applied, after which the discs are metalized and lacquer-coated. The write laser of the CD recorder changes the color of the dye to allow the read laser of a standard CD player to see the data, just as it would with a standard stamped disc. In Computing, an optical disc drive ( ODD) is a Disk drive that uses Laser light or electromagnetic waves near the Light spectrum A Compact Disc player (often written as compact disc player) or CD player, is an electronic device which plays audio Compact Discs CD players are often The resulting discs can be read by most CD-ROM drives and played in most audio CD players.

CD-R recordings are designed to be permanent. Over time the dye's physical characteristics may change, however, causing read errors and data loss until the reading device cannot recover with error correction methods. The design life is from 20 to 100 years, depending on the quality of the discs, the quality of the writing drive, and storage conditions. However, testing has demonstrated such degradation of some discs in as little as 18 months under normal storage conditions. ^[13][14] This failure is known as CD rot. CD rot (or DVD rot) is a phrase describing the tendency of CD or DVD disks to become unreadable due to physical or chemical deterioration CD-Rs follow the Orange Book standard. For the series of US government publications on Computer security standards see Rainbow Series.

Recordable Audio CD

The Recordable Audio CD is designed to be used in a consumer audio CD recorder. These consumer audio CD recorders use SCMS (Serial Copy Management System), an early form of digital rights management (DRM), to conform to the AHRA (Audio Home Recording Act). The Serial Copy Management System or SCMS was created in response to the Digital audio tape (DAT invention in order to prevent DAT recorders from making second-generation Digital rights management ( DRM) is a generic term that refers to Access control technologies used by hardware manufacturers publishers and Copyright holders The Recordable Audio CD is typically somewhat more expensive than CD-R due to (a) lower volume and (b) a 3% AHRA royalty used to compensate the music industry for the making of a copy. ^[15]

High Capacity Recordable CD

A higher density recording format that can hold about:

• 98. 5 minutes of audio on a 12 cm disc (compared to about 80 minutes for Red Book audio). Red Book is the standard for audio CDs ( Compact Disc Digital Audio system or CDDA)
• 30 minutes of audio on an 8 cm disc (compared to about 24 minutes for Red Book audio). Red Book is the standard for audio CDs ( Compact Disc Digital Audio system or CDDA)

ReWritable CD

Main article: CD-RW

CD-RW is a re-recordable medium that uses a metallic alloy instead of a dye. Compact Disc ReWritable (CD-RW is a rewritable Optical disc format Compact Disc ReWritable (CD-RW is a rewritable Optical disc format The write laser in this case is used to heat and alter the properties (amorphous vs. crystalline) of the alloy, and hence change its reflectivity. A CD-RW does not have as great a difference in reflectivity as a pressed CD or a CD-R, and so many earlier CD audio players cannot read CD-RW discs, although most later CD audio players and stand-alone DVD players can. DVD (also known as " Digital Versatile Disc " or " Digital Video Disc " - see Etymology)is CD-RWs follow the Orange Book standard. For the series of US government publications on Computer security standards see Rainbow Series.

High Speed ReWritable CD

Due to technical limitations, the original ReWritable CD could be written no faster than 4x speed. High Speed ReWritable CD has a different design that permits writing at speeds ranging from 4x to 12x.

Original CD-RW drives can only write to original ReWritable CD discs. High Speed CD-RW drives can typically write to both original ReWritable CD discs and High Speed ReWritable CD discs. Both types of CD-RW discs can be read in most CD drives.

Even higher speed CD-RW discs, Ultra Speed (16x to 24x write speed) and Ultra Speed+ (32x write speed), are now available.

ReWritable Audio CD

The ReWritable Audio CD is designed to be used in a consumer audio CD recorder, which won't (without modification) accept standard CD-RW discs. These consumer audio CD recorders use SCMS (Serial Copy Management System), an early form of digital rights management (DRM), to conform to the AHRA (Audio Home Recording Act). The Serial Copy Management System or SCMS was created in response to the Digital audio tape (DAT invention in order to prevent DAT recorders from making second-generation Digital rights management ( DRM) is a generic term that refers to Access control technologies used by hardware manufacturers publishers and Copyright holders The ReWritable Audio CD is typically somewhat more expensive than CD-RW due to (a) lower volume and (b) a 3% AHRA royalty used to compensate the music industry for the making of a copy. ^[15]

Copy protection

Main article: CD/DVD copy protection

The Red Book audio specification, except for a simple 'anti-copy' bit in the subcode, does not include any serious copy protection mechanism. CD/DVD copy protection is a blanket term for various methods of Copy protection for CDs and DVDs Such methods include DRM, CD-checks Dummy Red Book is the standard for audio CDs ( Compact Disc Digital Audio system or CDDA) Copy protection, also known as content protection, copy prevention, or copy restriction, is a technology for preventing the unauthorised reproduction Starting in early 2002, attempts were made by record companies to market "copy-protected" non-standard compact discs, which cannot be ripped (copied) to hard drives or easily converted to MP3s. See also 2002 (disambiguation Year 2002 ( MMII) was a Common year starting on Tuesday of the Gregorian calendar. Ripping is the process of copying audio or video content to a Hard disk, typically from Removable media or media streams. MPEG-1 Audio Layer 3, more commonly referred to as MP3, is a Digital audio encoding format using a form of Lossy data compression One major drawback to these copy-protected discs is that most will not play on computer CD-ROM drives, as well as some standalone CD players that use CD-ROM mechanisms. Philips has stated that such discs are not permitted to bear the trademarked Compact Disc Digital Audio logo because they violate the Red Book specification. A trademark or trade mark, represented by the symbols ™ and ®, or mark is a distinctive sign or indicator used by an individual Numerous copy-protection systems have been countered by readily-available, often free, software.

See also

References

Further reading

• du Gay, Paul, Stuart Hall, Linda Janes, et. al (1997). Doing Cultural Studies: The Story of the Sony Walkman. Thousand Oaks, California: SAGE Publications.
• Ecma International. Ecma International (Ecma is an international private (membership-based non-profit Standards organization for information and communication systems Standard ECMA-130: Data Interchange on Read-only 120 mm Optical Data Disks (CD-ROM), 2nd edition (June 1996).
• Pohlmann, Kenneth C. (1992). The Compact Disc Handbook. Middleton, Wisconsin: A-R Editions. ISBN 0-89579-300-8.

External links

• Philips history of the CD
• Sony's CD history
• How CDs work at HowStuffWorks
• Patent History (CD Player) - published by Philips 2005
• Patent History CD Disc - published by Philips 2003
• Sony History, Chapter 8, This is the replacement of Gramophone record ! (第8章 レコードに代わるものはこれだ)Sony web site in Japanese