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However, in 1985 Yellow Book CD-ROM standard was established by Sony and Philips, which defined a non-volatile optical data storage medium using the same physical format as audio compact discs, readable by a computer with a CD-ROM drive. For its first few years of existence, the compact disc was purely an audio format.
. The originally CD-only label Ryko extended this system to the other media when it began making LPs and cassettes so that a digital recording on an LP would be DDA, and so forth.

A notable example is Herb Alpert's Rise album from 1979. A few examples of DAD recordings exist, mostly of works that were originally recorded digitally but later remixed by artists who preferred to work with analog technology. Two examples from 1982 are Signals by Rush and The Nightfly by Donald Fagen. By the time the compact disc was introduced worldwide digital recording and mixing was becoming commonplace among recording artists and producers known for their interest in fidelity.

An early example of an analog recording that was digitally mixed is Fleetwood Mac's 1979 release Tusk. Martin used digital mixing, however, to eliminate the distortion and noise that an analog master tape would introduce (thus ADD). Others, such as former Beatles producer George Martin, felt that the multitrack digital recording technology of the early 1980s had not reached the sophistication of analog systems. Stevie Wonder adopted the technology in early 1979 for Journey Through the Secret Life of Plants and used it on all later recordings.

Many other top recording artists were early adherents of digital recording. It was unmixed, being recorded straight to a two-track 3M digital recorder in the studio. The first digitally recorded (DDD) popular music album was Ry Cooder's Bop Till You Drop, recorded in late 1978. (Unmixed analog recordings are likewise usually described as ADD to denote a single generation of analog recording).

These unmixed digital recordings are still described as DDD since the technology involved is purely digital. In most cases there was no mixing stage involved; a stereo digital recording was made and used unaltered as the master tape for subsequent commercial release. The first 16-bit PCM recording in the United States was made by Thomas Stockham at the Santa Fe Opera in 1976 on a Soundstream recorder. Commercial digital recording of classical and jazz music began in the early 1970s, pioneered by Japanese companies such as Denon, although experimental recordings exist from the 1960s.

Often this code was accompanied by a short description such as "Full Digital Recording" for DDD and "Digitally Mixed Analog Recording" for ADD. Almost all early CDs are "AAD" (analog recording and mixing, digital transfer to CD) as a result. The first letter represents how the album was recorded, the second how it was mixed, and the third how it was transferred (inevitably a D, as the CD is a digital medium). Many CDs, especially classical music and many popular recordings, come with a three-letter code printed on the back known as the SPARS (acronym for Society of Professional Audio Recording Studios) Code, where "A" stands for analog and "D" stands for digital.

Note that the CD+G or “karaoke” extension also uses the R-W subchannels or subcodes to store low resolution graphics. ITTS is also used by Digital Audio Broadcasting or the MiniDisc. The text is stored in a format usable by the Interactive Text Transmission System (ITTS). About 31 megabytes of information can be stored there.

The information is stored in the lead-in area of the CD, where there is roughly five kilobytes of space available, or in the R through W Subchannels on the disc, which are not used by strict Red Book CDs. album name, song name, and artist) on a standards-compliant audio CD. It allows for storage of additional information (e.g. CD-Text is part of the CD+G extension to the Red Book standard for audio CDs.

Channels R…W are unused by Red-Book compliant CDs, and have been used for extensions to the standard. The ISRC is used by the media industry, and contains information about the country of origin, the year of publication, owner of the rights, as well as a serial number, and some additional tags:. It contains positioning information, the Media Catalog Number (MCN), and International Standard Recording Code (ISRC). Channel Q is used for control purposes of more sophisticated players.

Quite a few players ignore it in favor of the Q Channel. Channel P is a simple pause/music flag, which can be used for low-cost search systems. These streams are called "channels", and are labeled starting with the letter P, like so:. Each of these bits corresponds to a separate stream of information.

Each of the 96 subchannel data bytes can be thought of as being divided into eight bits. 1 byte for command, 1 byte for instruction, 2 bytes for parityQ, 16 bytes for data, and 4 bytes parityP. The 96 bytes of subchannel information in each sector contain four packets of 24 bytes apiece:. In each sector there are 2352 bytes (24×98) of audio content data and 96 bytes of subchannel data.

Thus each channel has a bit rate of 7.35 (=44.1/6) kbit/s. The eight bits are used as eight different subcoding channels, and given letters designating their usage: P, Q, …, W. The eight bits of a subcode byte are available for control and display. A frame comprises 33 bytes, of which 24 are audio bytes (six full stereo samples), eight error correction, CIRC-generated, bytes plus one subcode byte.

The data in a CD are arranged in frames. Besides digital audio, a CD contains digital data called "subcode", which is multiplexed with the digital audio. ... An audio CD has a very different structure:.

A CD-ROM (data) sector contains 2352 bytes:. A 1x speed CD drive reads 75 consecutive sectors per second. The playing time is 74 minutes, or 4440 seconds, so that the net capacity of a Mode-1 CD-ROM is 682 MB. The net byte rate of a Mode-1 CD-ROM is 44.1k×2048/(6×98) = 153.6 kB/s.

In a Mode-2 CD-ROM, which is mostly used for video files, there are 2336 user-available bytes per sector. A Mode-1 CD-ROM, which has the full third layer error correction capability, contains a net 2048 bytes of the available 2352 per sector. Note that the CIRC error correction system used in the CD audio format has two interleaved layers. In order to achieve improved error correction and detection, a CD-ROM has a third layer of Reed-Solomon error correction.

The CD-ROM is in essence a data disc, which cannot rely on error concealment, and it requires therefore a higher reliability of the retrieved data. A CD-ROM sector contains 98 frames, and holds 98×24 = 2352 bytes. The synchronization word cannot occur in the normal bit stream, and can thus be used to identify the beginning of a frame. A 27-bit unique synchronization word is added, so that the number of channel bit in a frame totals 588.

In total we have 33*(14+3) = 561 channel bits. The eight bits of a subcode byte are available for control and display. A frame comprises 33 bytes, of which 24 are audio bytes (six full stereo samples), eight error correction, CIRC-generated, bytes plus one subcode byte. Data in a CD-ROM are organized in both frames and sectors.

2×2×6 = 24 bytes. A frame can accommodate six complete 16-bit stereo samples, i.e. The smallest entity in the CD audio format is called a frame. Each 14-bit EFM word alternates with a 3-bit merging word.

Each 14 consecutive bits are grouped and decoded using Eight-to-Fourteen Modulation to get a byte. As bit-times are counted off, a transition (pit-to-land, or land-to-pit) is interpreted as a "1" bit, while a constant region (all-land or all-pit) is interpreted as a "0" bit. Under a microscope, all that is visible is a series of various-sized pits arranged in a long spiral, starting near the inner hole. A "4.7 GB" DVD has a nominal capacity of about 4.38 GiB.

But DVD capacities are given in decimal units. A "700 MB" (or "80 minute") CD has a nominal capacity of about 700 MiB. CD capacities are always given in binary units. 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.

CDs would often be released with one or more bonus tracks, enticing consumers to buy the CD for the extra material. The 74-minute playing time of a CD, being more than that of most long-playing vinyl albums, was often used to the format's advantage during the early years when CDs and LPs vied for commerical sales. However, these discs can cause problems in playback when the end of the disc is reached. Another technique to increase the capacity of a disc is store data in the lead out groove that is normally used to indicate the end of a disk, and an extra minute or two of recording is often possible.

This is the limit for most conventional audio CDs today. Using a linear velocity of 1.2 m/s and a track pitch of 1.5 micrometre leads to a playing time of 80 minutes, or a capacity of 700 MB. A disc with data appearing slightly more densely is allowable. If the disc diameter were 115 mm, the maximum playing time would have been 68 minutes, i.e., six minutes less.

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. The program area is 86.05 cm², so that the length of the recordable spiral is 86.05/1.6 = 5.38 km. The main parameters of the CD (taken from the September 1983 issue of the compact disc specification) are as follows:. The Sony PCM-1610 and PCM-1630 are well known examples of PCM adaptors used in conjunction with the Sony U-matic VCR.

There was a long debate over whether to use 14 or 16 bit samples and/or 44,056 or 44,100 samples/s when the Sony/Philips task force designed the compact disc; 16 bits and 44.1 kilo-samples/s prevailed. This system could either store 14-bit samples with some error correction, or 16-bit samples with almost no error correction. Similarly PAL has 294 lines and 50 fields, which gives 44,100 samples/s. A standard NTSC video signal has 245 usable lines per field, and 59.94 fields/s, which works out at 44,056 samples/s.

This technology could store six samples (three samples per each stereo channel) in a single horizontal line. A 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. The sampling rate of 44.1 kHz is inherited from a method of converting digital audio into an analog video signal for storage on video tape, which was the most affordable way to store it at the time the CD specification was being developed. Reed-Solomon error correction allows the CD to be scratched to a certain degree and still be played back.

In broad terms the format is a two-channel (four-channel sound is an allowed option within the Red Book format, but has never been implemented) stereo 16-bit PCM encoding at a 44.1 kHz sampling rate. Philips is responsible for the licensing program of the intellectual property pertinent to the Compact Disc including the "Compact Disc Digital Audio" logo that appears on the disc. The format of the audio disc, known as the "Red Book" / Sony standard, was laid out by Sony and Philips in 1981. Bulk packaging can be done before or after printing.

Sometimes the spindle of 150 discs are shrinkwrapped together in bulk. The finished assembly has security stickers applied, and is shrinkwrapped with marketing stickers applied. Printing and Packaging: The label is printed onto the disc using a one to six color process (in the case of silk screening), then the printed discs are loaded into a packaging macine that combines a jewel box, tray card, the disc, and booklet. The discs are sampled by QC to ensure quality product.

A laquer is spin coated onto the disc and the disc is tranfered to a spindle. At this point the disc is clear, so a coating of aluminum or gold is applied to the disc for reflectivity. The chamber opens and a robotic arm grabs the disc and transfers it to the next stage. Melted polycarbonate resin is injected into the chamber and the CD is pressed using up to 40 tons of pressure.

Pressing: Each stamper is mounted in an injection moulding machine. This process is also done in a clean room environment. Each stamper is quality checked. Multiple stampers can be made from one glass master.

Stamper Process: Next the glass master is used to create nickel stampers using an electroplating technique. The glass master produced is quality checked before it moves to the next stage. Source material is encoded into the appropriate format whereupon a computer controlled machine "burns" the pits into the emulsion layer of the glass master. The glass is coated with an emulsion.

The nickel is transfered by exciting the nickel to a plasma state whereupon a thin layer of nickel will adhere to the glass. Mastering Process: First, in a clean room, a glass master is prepared by coating a perfectly flat piece of half inch thick circular glass with a layer of nickel. Discs are consequently much easier to ruin by scratching the label side, whereas clear-side scratches can be repaired by refilling them with plastic of similar index of refraction. 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.

Most CD manufacturers, dependent on the exact pit geometry such as the slope of the pit edges etc, choose a pit depth of around 90-100 nm, (which is around λ/6n) yielding a sound trade-off between the quality of the push-pull radial tracking and full aperture detection signal. For a maximum push-pull radial tracking signal the best choice is λ/8n = 65 nm. For a maximum full aperture signal, the optimum pit depth is λ/4n = 130 nm (refractive index n=1.5, λ=780 nm). However, the Red Book implicitly specifies the pit depth by specifying the strength of both the push-pull radial tracking signal and full aperture detection signal.

It specifies that the pit depth should be less than (and, thus, not equal) 130 nm. Figure 1, page 8a, of the Red Book specifies many mechanical parameters including the pit depth. This in turn is decoded by reversing the Eight-to-Fourteen Modulation used in mastering the disc, finally revealing the raw data stored on the disc. Instead a change from pit to land or land to pit indicates a one, while no change indicates a zero.

The pits and lands themselves do not represent the zeroes and ones of binary data. By measuring this intensity with a photodiode, one is able to read the data from the disc. The destructive interference thus reduces the intensity of the reflected light compared to when the laser is focused on just a land. The difference in height between pits and lands is one quarter to one sixth of the wavelength of the laser light, leading to a half-wavelength or less phase difference between the light reflected from a pit and from its surrounding land.

A CD is read by focusing a 780 nm wavelength semiconductor laser through the bottom of the polycarbonate layer. The spiral begins at the center of the disc and proceeds outwards to the edge, which allows the different size formats available. To grasp the scale of the pits and land of a CD, if the disc is enlarged to the size of a stadium, a pit would be approximately the size of a grain of sand. The spacing between the tracks is 1.6 μm.

(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 3.5 μm long. The information on a standard CD is encoded as a spiral track of pits moulded into the top of the polycarbonate layer. There is a 15 mm hole in the centre of the disc, usually used by some form of clamp or clip device within the player to hold it in place and allow it to be rotated by a motor. Some irregularly shaped discs will work with tray loading CD drives if they include a circular ridge on their underside which centers them on the part of the tray designed to hold 80 mm CDs, assuming the tray has such a feature.

Irregularly shaped, non rotationally symmetric discs with an offset centre of mass may also cause damaging vibration if played in computer CD drives, which can operate at a much higher rotational velocity than stand-alone audio CD players. Examples include Business Card CDs in the shape of a rectangular card and CDs shaped like the map of a country etc, although such discs are not always compatible with all CD players — they will work with any machine where the disc is inserted by manually clipping it onto the spindle (the mechanism used in virtually all portable CD players), but may not necessarily be inserted into drives which load the disc from a tray, or pull it into a slot. Other unique shapes and smaller form factors have also been sold or given away as promotional items. Each such "miniCD" or "Maxi CD" can hold 21 minutes of music, or 180 MB of data (this form factor has also been called "CD3", since it is about three inches across).

Japan), much like the old vinyl single. 80 mm discs are also available, a format which is mainly used for audio CD singles in some regions (e.g. Such a standard disc weighs 15 grams. By far the most common is 120 mm in diameter, with a 74-minute audio capacity and a 650 MB data or a 80-minute audio capacity and a 700 MB data (See storage capacity; this form factor has also erroneously been called "CD5" since it is 4 3/4 inches in diameter, about five inches across).

CDs are available in two sizes. Common printing methods for compact discs are silkscreening and offset printing. The lacquer can be printed with a label. Compact discs are made from a 1.2 mm thick disc of polycarbonate plastic coated with a much thinner layer of Super Purity Aluminium (or rarely, gold, used for its data longevity, such as in some limited-edition audiophile CDs) layer which is protected by a film of lacquer.

The CD and its later extensions have been extremely successful: in 2004 the annual worldwide sales of CD-Audio, CD-ROM, and CD-R reached about 30 billion discs. A user-recordable CD for data storage, CD-R, was introduced in the early 1990s, and it became the de facto standard for exchange and archiving of computer data and music. A CD can store around 640 megabytes of data. With this it was now possible to disseminate massive amounts (for the time) of computer data instead of digital sound.

Two years later, in 1985, the CD-ROM (read-only memory) was introduced. From its origins as a music format, Compact Disc has grown to encompass other applications. [2]. It spurred the sale of compact disc players like no other recording before it, helped to drive down the price of players, induced other acts and record labels to release more music on CD and firmly established the format in the mind of the average consumer.

One of the first all-digital rock recordings and the first by a major act, Brothers in Arms played to the strengths of the CD by offering more and longer tracks, running ten minutes longer than the album's concurrent LP and cassette releases. This "highbrow niche" status of the CD format changed dramatically in May, 1985, when UK rock band Dire Straits released the album Brothers in Arms. The far larger popular and rock music industries were slower to adopt the new format, especially in the huge consumer markets in Europe and the United States. The new audio disc was enthusiastically received, especially in the early-adopting classical music and audiophile communities and its handling quality received particular praise.

This event is often seen as the "Big Bang" of the digital audio revolution. The Compact Disc reached the market in late 1982 in Asia and early the following year in other markets. According to Philips, the Compact Disc was thus "invented collectively by a large group of people working as a team."[1]. The Compact Disc Story, 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.

Philips also contributed the Eight-to-Fourteen Modulation, EFM, which offers both a large playing time and a high resilience against disc handling damage such as scratches and fingerprints; while Sony contributed the error-correction method, CIRC. Philips contributed the general manufacturing process, based on the video Laserdisc technology. After a year of experimentation and discussion, the taskforce produced the "Red Book", the Compact Disc standard. Prominent members of the task force were Kees Immink and Toshitada Doi.

In 1979 Philips and Sony decided to join forces, setting up a joint task force of engineers whose mission was to design the new digital audio disc. At the end of the 1970s, Philips, Sony, and other companies presented prototypes of digital audio discs. In the early 1970s, using video Laserdisc technology, Philips' researchers started experiments with "audio-only" optical discs, initially with wideband frequency modulation FM and later digitized PCM audio signals. .

Online services such as CDDB were developed to work around these shortcomings in the computer age. As a result, the original CD format has a number of limitations; no built-in track names or disc naming for example. Only later did the concept of an 'audio file' arise, and the generalising of this to any data file. The design of the CD was originally conceived as an evolution of the gramophone record, rather than primarily as a data storage medium.

Compact disc technology was later adapted for use as a data storage device, known as a CD-ROM. They hold about 20 minutes of audio. The 80 mm discs are used as "CD-singles" or novelty "business-card CDs". The 120 mm discs can hold 74 minutes of audio, and versions holding 80, 90 or even 99 minutes have been introduced.

Standard compact discs have a diameter of 120 mm, though 80 mm versions exist in circular and "business-card" forms. An audio CD consists of several stereo tracks stored using 16-bit PCM coding at a sampling rate of 44.1 kHz. A standard compact disc, often known as an "audio CD" to differentiate it from later variants, stores audio data in a format compliant with the red book standard. It is the standard playback format for commercial audio recordings today.

A compact disc (or CD) is an optical disc used to store digital data, originally developed for storing digital audio. ISBN 895793008. Middleton, Wisconsin: A-R Editions. The Compact Disc Handbook.

Pohlmann (1992). Kenneth C. 458-465, May 1998 [4]. Kees Immink, The Compact Disc Story, AES Journal, pp.

AAD: analog tape recorder used during session recording and subsequent mixing and/or editing, digital tape recorder used during mastering (transcription). ADD: analog tape record used during session recording, digital tape recorder used during subsequent mixing and/or editing and during mastering (transcription). DDD: digital tape recorder used during session recording, mixing and/or editing, and mastering (transcription). 276 bytes: error correction.

8 bytes: null. 4 bytes: error detection. 2 048 bytes: user data. 4 bytes: sector ID.

12 bytes: sync. Outer radius program area: 58 mm. Inner radius program area: 25 mm. Disc thickness: 1.2 mm.

Disc diameter 120 mm. Track pitch: 1.6 μm. Scanning velocity: 1.2–1.4 m/s (constant linear velocity) - Equivalent to about 500 rpm at the inside of the disc, or about 200 rpm at the outside edge.