2011-05-03T00:55

2011-05-03T00:55

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How to power a CD?

The design of the CD-DA disc (Compact Disk - Digital Audio, compact disc - digital audio) and the method of recording sound on a new one is described by the standard of the company, which was promoted by Sony and Philips, we see in 1980 the name Red Book (Chervona Book).

A standard compact disc (CD) is made up of three balls: the basics that make it good. The base of the viconan is made of translucent polycarbonate, on which the informational relief is formed by the pressing method. On top of the relief, a metal ball is sawn, which is used (aluminum, gold, silver, other metals and alloys). When the ball is covered with a ball of polycarbonate or neutral varnish - so that the entire metal surface of the bula is protected from contact with the outer core. The thickness of the disc is 1.2 mm.

The informational relief of the disk is a continuous spiral path that starts in the center and is composed of a sequence of burying - pits. Spaces between pits are called lands. The number of intervals and intervals of different periods of time is recorded on the disk with a digital signal encoding: the transition from the interval to the interval and the next indicates one, and the interval of the interval or the interval - the interval of the series of zeros. The distance between the turns of the track is selected from 1.4 to 2 microns, the standard is 1.6 microns.

How does a disc sound?

The output stereo audio signal is digitized in 16-bit audio (linear quantization) with a sampling frequency of 44.1 kHz. The negative digital signal is called PCM (Pulse Code Modulation - pulse code modulation, ІКМ), the skin pulse of the output signal is represented by a code word. The skin of the left and right channels are processed in the first frame, or microframes, 24 bytes (192 bits) wide, which should be 7350 pieces per second, which are coded for the additional CIRC code (Cross Interleaved) according to the scheme: interleaved from the trim by 1 byte, encoded with C2, cross-interleaved with the interleaved trim, encoded with equal C1, interleaved from the trim by 2 bytes. Riven C1 appointments for the detection and correction of single pardons, C2 - for group pardons. As a result, a block of up to 256 bits will be output, given in a way that is safe by the ranks of the correction of pardons, and before that it is "smeared" to the block, so that the total sound data in the physically non-contiguous areas of the disk can be recorded before recording, and the pardons are lowered on the other areas of the disk.

The Reed-Solomon code can have an overworld of 25% and allows you to display up to a few pardon bytes and a correction up to a couple of pardons or two pardon bytes. The maximum length of a package of pardons, which will be corrected again, is about 4000 bits (~ 2.5 mm of the length of the path), if there is no such package, then there may be more corrections.

After another interleaving of the skin block, a series of subcodes is added - P, Q, R, S, T, U, V, W; skin block otrimuє vіsіm subkodnyh battles. Then 98 skin blocks with subcodes are formed into one overframe with a trivality of 1/75 sec (the total amount of pure sound data is 2352 bytes), the titles are also a sector, in which the subcodes of the first two blocks serve as a sign of synchronization, and 96 ranks of the skin subcode, which are missing, establish P -word, Q-word too. The sequence of subcode lines is also called subcode channels as a stretch of the track.

Words chi channels of subcodes are selected for recording by the recording format, indication of fragments in phonograms is also limited. - for example, channel P is used for identifying audio tracks and pauses between them (0 - pause, 1 - sound), and channel Q - for identifying the format of tracks and sectors, recording TOC (Table Of Contents) and time marks, which is the hour of creation. The Q channel can also be used for recording information in ISRC (International Standard Recording Code - international standard recording code), recognized for the presentation of information about the virobnik, an hour later, and also for the bottom of the track on okremі fragments (the whole sound disc can be up to 99 audio tracks, the skin of which can include up to 99 fragments).

By the way, framed in this way, the frames are encoded to the channel coding in terms of "short - intermittent" with the variation of the superfluous code 8/14 (Eight to Fourteen Modulation - EFM), in which case the bytes are encoded with 14-bit words, which increases the parsing of the signal. Between words, three successive bits are inserted to complete the exchange for a number of sum zeros and one, which makes it easier to demodulate and change the constant warehouse signal. As a result of the skin primary microframe, 588 channel bits are output, and the bit stream is removed and recorded on a disk with a speed of 4.3218 (588 x 7350) Mbit/s. EFM-encoding oscillators give a digital stream, in which zeros are greater, lower ones, and the system of representing ones between the two and the interval was selected, and the number of zeros between the ones - the old one or the interval is clear.

On the top of the disc, there is a so-called lead-in zone, which contains information about the disc format, the structure of sound programs, the addresses of fragments, the names of works, etc. For example, a visible (lead-out) zone (track with the number AA) is recorded, which plays the role of the inter-recorded area of ​​the disk; The P-code bit for this zone is changed from the frequency of 2 Hz. A number of pobootovyh progravachіv can't recognize a disk without a zone zone, but someone can do without it. Between the introductory and visible zones, a program area (Program Memory Area - PMA) is recorded to avenge sound data. The program area is added to the entry zone with a slot of 150 empty blocks (2 seconds), which plays the role of the gap (pre-gap).

The total cost of recording on a CD is 74 times, but with a change in the standard track size and distance between pits, it is possible to achieve an increase in the recording time - for the cost of reducing the speed of reading in a standard disk drive.

How are CDs recorded and made?

The main way to prepare disks is to press from matrixes. The original is formed from a free digital master-string, which can be used to prepare and encode a digital signal, with a special high-precision workbench on a glass disk covered with a ball of photoresist - a material that changes its size under the infusion of a laser exchange. When processing the original recorded by the retailer on the slate, the necessary relief is necessary, which is transferred to the nickel original (negative) by electroforming, which can serve as a matrix for serial production, or the basis for taking positive copies, which, from their own hand, are known to be negatives.

Stamping is done using the casting method under a vice: a polycarbonate lining with a relief is pressed from a negative matrix, a ball is sawed to the beast, which is vibrated, which is covered with varnish. On top of the zahisny ball, sound the informational inscriptions and the image.

Recordable discs (CD-R, "blanks") are prepared in the same way, but between the base and the ball, which beats, the ball of organic speech expands, which darkens when heated. In front of the station there is a piercing ball, with the influx of a laser exchange, opaque dilyankas, equivalent to pits, are established. To ease the step behind the track, when recording to the disk, a front relief (marking) is formed in the preparation process, the track to remove the marks of the frame and the synchronization signals recorded with a reduced amplitude and the year are crossed by the signal that is being recorded.

The discs that are recorded, for the account of the presence of an organic fixing ball, may have a lower coefficient of fermentation, lower stamping, which is why the work of the engraver (Compact Disk Player - CDP), are protected on standard aluminum discs superficially, inferiorly.

How do CDs work?

When playing an audio CD, it wraps with a constant linear velocity (Constant Linear Velocuty - CLV), when the velocity of the track is approximately 1.25 m/s. The system for stabilizing the speed of the wrapping is supported on such a level, in order to secure the speed of a licensed digital stream, which costs 4.3218 Mb/s, so it can be changed. The top speed of the disc changes at 500 rpm when reading the inner tracks of the track up to 200 rpm on the outside.

To read information from the disk, a conductor laser is used from a long hair at about 780 nm (infrared range). Passing the laser passing through the focusing lens, it falls on the ball, which hits it, it hits the light at the photodetector, de-emphasizes the focusing of the light and the space, as well as rechecking the brightness of focusing with the flames on the road and the left orifice on the center of the door. When focusing is disturbed, the lens moves, which works on the principle of the speaker diffuser (voice coil), when the entire head moves along the radius of the disk when it moves out of the center of the track. In fact, the systems of steering with a lens, a head and a spindle motor at the drive and automatic control systems (ACS) and are in the mode of constant speed for the chosen path.

Removing the photodetector signal code 8/14 is demodulated, as a result of which the result of encoding by CIRC with the addition of subcodes is confirmed. We will then carry out the addition of subcode channels, deinterleaving and decoding of CIRC on a two-stage corrector (C1 - for single pardons and C2 - for group pardons), as a result of which a large part of the pardons caused by damage during stamping, defects and heterogeneity on the disc material superficial, fuzzy designation of a pet/promotion at the photodetector then. Through the war, the flow of "pure" sound signals to the DAC was converted to an analog form.

In sound programmers, after the corrector, there is also an interpolator of different folding, which approximately restores the pardons, as if it was not possible to correct it in the decoder. Interpolation can be linear - in the simplest direction, polynomial or with multiple folds of smooth curves.

For vikonannya deinterleaving whether a CD-reader attachment may buffer memory (standard size - 2 KB), as at the same time vykoristovuetsya to stabilize the speed of the digital stream. For decoding, it is possible to select a few different strategies, in which the manifestation of group pardons is wrapped in proportion to the supremacy of their corrections; The choice of strategy depends on the decoder's retailer. For example, for a CD-programmer with a tight interpolator, a strategy can be selected with an emphasis on maximum exposure, and a CDP with a simple interpolator or a CD-ROM drive - on maximum correction.

What are the parameters for the sound signal of a CD?

The standard digitization parameters - sampling frequency 44.1 kHz and bit depth for 16 - determine the theoretically calculated characteristics of the signal:

• Frequency range: 0..22050 Hz
• Dynamic Range: 98 dB
• Noise Rating: -98 dB
• Non-linear rate: 0.0015% (at maximum signal level)

In real attachments, CD recordings of upper frequencies are often cut at 20 kHz to adjust the margin for the coolness of the frequency response of the filter. The noise level can be less than 98 dB for a different linear DAC and a noisy out-of-band amp, and more - for oversampling times at a higher frequency with different DACs of the Delta-Sigma type, Bitstream or MASH and low-noise amps. The coefficient of non-linear creations is heavily deposited in the presence of a stagnant DAC of the lances that live like a life.

Dinami DIAPAZON 98 dB is tortured for CD, Vidnici with the maximum of the sound signal, the prote on the small signal is simply the sparrowing of the dinemino, the dintering of the din.

What is jitter?

Jitter is a constant triviality for the period of the third phase of the digital signal, if the strict evenness of the passage of the fronts of the impulses is broken. Such a triple fault is due to the instability of clock generators, as well as in the field of vision of a clock signal from a complex signal using the PLL method (Phase Locked Loop - a loop from a phase lock, or a phase auto-tuning of a frequency - PLL). Such a sight, for example, at the demodulator signal, read from the disk, after which the reference clock signal is established, which is a way of correcting the speed of the disk wrapping, "upgrades" to the reference frequency of 4.3218 MHz. The frequency of the sync signal, and also the second phase and the phase of the information signal, are constantly fluctuating with a different frequency. The addendum can be introduced by the unevenness of the roztashuvannya on the disk, generated, for example, by inaccurate compression or by an unstable record.

However, the unevenness of the signal from the disk is fully compensated by the input buffer of the decoder, so whether there is a third detonation that wins out before the signal is added to the buffer, at this stage it is reduced. Vibration from the buffer is controlled by a stable generator with a fixed frequency, so such generators can also be taman, although it is a little less, unstable. Zocrema, you can be viklikana with changes in the lances of life, yak, at your own pace, you can blame at the moment of the ATS spratsovuvannya and the correction of the disc speed or the position of the head / lens. On low-capacity disks, corrections are often made, giving a number of experts a drive to impair the stability of the output signal from the disk's brightness, although the real reason is the lack of good decoupling of CDP systems.

What do the abbreviations AAD, DDD, ADD mean?

Letters and abbreviations are used to form a sound signal, victorious when the disk is created: the first - when recording, the other - when processing that link, the third - the final master signal, from which the disk is formed. "A" means analog (analog) form, "D" - digital (digital). The master-signal for CD is always used only in digital form, so the third letter of the abbreviation is always "D".

І analog, і digital form the signal may have its own advantages and disadvantages. When recording and processing a signal in analog form the most important are the "thin elements", the main ones - the main harmonics, the noise protection and the amplitude-frequency and phase-frequency characteristics (AFC / PFC). When processed in digital form, the primary harmonics are formed at half the sampling frequency, and often even lower, while all further operations are limited to the maximum possible accuracy for the opposite. The signal, which passed through the analog processing, is estimated by experts as "warm" and "lively", modern methods The signal processing is more conveniently implemented in the digital version.

Can two identical discs sound different?

First of all, it is necessary to reconsider that the discs are effectively replaced by an identical digital sound signal. Повний двійковий збіг двох дисків на рівні конфігурації пітів і проміжків практично неможливий за рахунок дрібних дефектів матеріалу і спотворень при обробці матриць і пресуванні, проте завдяки надмірному кодуванню переважна більшість цих помилок виправляється при декодуванні, забезпечуючи один і той же цифровий потік "високого рівня".

It is possible to replace digital disks by means of a way to read them from a CD-ROM drive, which supports the Read Long or Raw Read mode - reading "long sectors", as if they are actually CD-DA overframes with a volume of 2352 bytes of skins. More information can be found in the CD-ROM FAQ or in the Sound Programming Guide (CD-DA Grabbers/Rippers). You can also swap discs on studio equipment, so you can read discs digitally on a DAT recorder.

The reasons for blaming digital powers between similar-sounding discs may be a little bit. Acting to drive a CD-ROM and other devices for digital reading CD-DA can, by preventing direct copying, introduce into the signal a little memory for hearing (for example, zastosovuchichi polynomials that smooth out), and more drives that read commands for reading new frames are inaccurately and inaccurate. When preparing copies (transfers) of audio discs, especially in a pirated way, they are often copied with resampling to a different frequency (for example, 48 kHz DAT) with a further resampling to a different one, or through an analog path with a digital / analog conversion. A number of versions of recording programs for CD-R also navmisno or vaguely spoof the data, so the copy does not match the original.

It is required to indicate that a digital drive should be loaded in place of two discs when they are paired in the current system (CD-ROM, special attachments for matching the original / copy only), it does not mean that on that chi identical CDP code should also be signaled from them . Therefore, the most important way to determine the cause of corruption in the sound will be CDP with digital output, for every hour of listening to both discs, a recording is made on the storage. The next digital sequence will be shown from the signalograms, deprogramming the signal to be introduced in a slightly different way.

Understandably, before matching the original and the copy in such a way, it is necessary to reconsider in the repetition of the results of the multiple reading of the discs themselves. Various digital signalograms in which case can tell about the wrong reading of the disk, or I’ll rot the robot digital interfaces(Priymach, transmitter, cable, roses). The identity of digital data in case of repeated creation of multiple disks can be considered as a sufficient sign of the reliability of both the disks themselves, as well as the systems of reading, decoding and intermodular transmission.

Hearing-sounding discs may be correct - the most recognizable is the blind test (double-blind test). The essence of the method is that the expert (hearer) is not guilty of manipulating the equipment and the people who virobley їх, and the person herself, quite rank changing the disks, is not guilty of the nobility of the peculiarities of their place. In such a rank, as much as possible, they turn on whether they are drunk, among them there are "thin" and untrained people, one on one for equipment, and the expert's thought is vvazhaetsya borderline unprecedented.

What is HDCD?

High Definition Compatible Digital is a "supersystem" for encoding sound on CD, which uses the standard CD-DA format. Sound signal with a bite with a bunny by rosobranstya ry with the frequency of samples of the digitalitic, in the result, the main part is to be the main part, the yak dawn, the method of PCM, and the dodatkovs are clarified areas that are masked. . When an HDCD disc is played on the original CDP, only the main part of the signal is extracted, and when a special CDP is played, the decoder and the HDCD processor extract all the information about the signal from the digital code.

How do you deal with CDs?

Uniquely mechanical poshkodzhennya be-like from the surface, dragged onto the disk of organic retailers and that direct bright light, hitting that overgrowth of the disk. Writing on recording discs is only allowed to be done with olives or special felt-tip pens, under the pressure of the onslaught of sack or pir'yanikh pens.

With a Wiimann disc out of the box, beware of yogo peregina. One of the handy and safe methods involves the participation of two hands - the thumb of the left hand lightly presses on the latch, easing yoga, while the other hand takes the disc out of the latch. The method with the best of one hand, if the pointed finger loosens the fixator, and the great and middle finger lifts the disk, it means more precise adjustment, without any easy bending of the disk, otherwise the fixator’s paddles are broken.

A fermented disc can be washed with warm water with a sweet or non-aggressive surface-active speech (shampoo, cleaning powder), or with rinds, which are specially released. Non-delicate stains on a transparent ball can be polished - with polishing pastes, so as not to avenge organic retailers and oils, but with a great toothpaste.

What is a "green felt-tip pen" and what wine is needed?

Richly coristuvachіv this expertise confirms that the synthesis of such a rank, the disk gives more pure sound in high-class devices, attributing more accurate reading of digital information from the disk, which, in its own sight, can not be delivered safely. The system (driver and decoder) can properly read not only unbroken discs, but also discs of medium hardness, possible reasons full of sounding next shukati over the disk. The best explanations for this phenomenon are those factors, which create different sounding of disc copies that run digitally.

Where to know more detailed information about CDs?

Optical discs are a popular carrier of information. More koristuvachiv know only CD and DVD discs, indeed, the views of the disks are much larger. Krajina Glad to tell you, yak see discs, and I will help you to find out in їkhnyu raznomanіttі.

See CDs

CDs or CDs, first of all, they were recognized for recording that creation of music, but now they are used for collecting practical computer information. Recording and reading information on disks is carried out with the help of a laser. The thickness of the CD is 1.2 mm, the diameter is 120 mm, the capacity is 650 or 700 MB (it has 74 or 80 sound lengths). Іsnuyut min CD with a diameter of 80 mm, ale їх ємніст less - 190-200 MB (21 sounds). Mini CDs can be read to anyone who wears the car radio. Buvayut figured CDs different forms, they are released more importantly for commercial purposes. Such disks are not recommended to be stuck in computer drives, because high speed the stink wrapper can peel off.

CDs can be split into CD-ROM, CD-R and CD-RW. Tsey podіl obumovleno mozhlivistyu write down on the disk information and recognition of the disk. Information on disk CD-ROM recorded by a scribe, it is not possible to change or see it, you can read the data. On disks CD-R(they are sometimes called "blanks") you can write down your information, but it will be impossible to erase it or change it. As if there was no more space left on the disk, and when recording, you allowed the option to add information, you can add files to the disk. Disks CD-RW trimming and overwriting information, but such disks are not readable by all drives.

See DVD discs

DVD discs allow you to save more information, lower CDs and laser lights with less longevity. DVD disc capacity standard size(120 mm) can be sized from 4.7 GB up to 17 GB, and the minimum capacity of DVD (80 mm) is 1.6 GB.

Fallow in the capacity of DVDs, they see the same type of discs:

• DVD-5- one-spherical one-sided disk, capacity - 4.7 GB
• DVD-9- double-sided single-sided disk, capacity - 8.5 GB
• DVD-10- Single ball double sided disk, capacity - 9.4 GB
• DVD-14- double-sided disk, two-ball from one side and one-ball - from the other, capacity - 13.24 GB
• DVD-18- Double ball double sided disk, capacity - 17.1 GB

Two ball disks hold two information balls from one side, they are designated by the abbreviation DL. Double-sided disc - actually two discs glued with non-working surfaces. Obviously, the size of such a disc is controlled in order to confirm the size of a superb one-ball DVD.

According to the possibility of recording, rewriting that remote information DVD discs, like CDs, can be divided into ROM, R and RW. Ale dodatkovo separate the following types of discs:

• DVD-R, DVD-R(G)- once burning a disc, assignments for home victoria.
• DVD-R for car, DVD-R(A)- once recording a disc for professional purposes.
• DVD-RW- Rewrite the disc. You can overwrite or delete information up to 1000 times. But you can’t erase part of the information, you can only erase the disk and overwrite it again.
• DVD-RAM vikoristovuyut technology change phase. You can rewrite up to 100,000 times, the theoretical term of service is up to 30 years. But stinks are expensive, they are issued more importantly in special cartridges and are supported by more drives and engravers.
• DVD+RW based on CD-RW technology that supports overwriting information up to 1000 times. Tsey format z'yavivaya pіznіshe for DVD-RW.
• DVD+R- once burning a disc, similar to DVD-R.

I realized that I would like to drive or the program does not support all DVD formats. Most of today's drives support both DVD-R(W) and DVD+R(W). Ale old bring that pleyers, released before the DVD + R (W) format appeared, read only DVD-R (W) discs. Establish "supermulti" drive, ie support all kinds of discs, including DVD-RAM.

Other types of discs

stand alone so called Dual Discs. Both discs have both CD and DVD formats. On one surface of such a disc, music is recorded in CD format, and on the other - five-channel sound, video, menu, subtitles, images, etc. in DVD format.

HD DVDs (High-width DVDs) mothers can up to 15 GB, and doubles up to 30 GB. Main competitor BD, Blu-ray Disc accommodating 23 to 66 GB fallow in number of balls. A prototype of a 100 GB choti-ball disk has been announced, and it is planned to release ten-ball disks with a volume of up to 320 GB.

Standing up to BD and HD DVD took away the title of "format war". Ale, the film studios decided to convert HD DVD to the speed of BD discs, to which the release of that support to the HD DVD format was officially attributed.

Otzhe, іsnuє impersonal vivid optical discs. Choose a disk for recording information warto, depending on its capacity, the ability to overwrite information and the model of your drive or a per-bit player. Knowing the main types of discs, you won't get lost in the current rich assortment.

A CD of creations in order to save audio recordings from a digital watch (like CD-Audio), the prote nadal became widely played like a nose for saving any data (files) from a double watch (t.v. CD-ROM- English. Compact Disc Read Only Memory CD with less readability, or CD-ROM- "Compact disc, permanent memory attachment"). Next, CDs appeared with the possibility of reading the information entered by them once, and recording ( CD-R- English. Compact Disc-Recordable , recording a CD) and overwriting ( CD-RW- English. Compact Disc-ReWritable , a CD that can be rewritable).

The first CD, which was consumed on the shelves of music stores, was Billy Joel's album of 1978 rock 52nd street. CD sales of this recording began in Japan on July 1, 1982.

For Philips' tribute, over 200 billion CDs were sold in the world in 25 years. I don’t care about those that more and more people value for better bathing music files via the Internet, following IFPI data, CD sales in 2007 accounted for close to 70% of all music sales.

A significant contribution to the popularization of CDs was made by Microsoft and Apple Computer. In 1987, John Scully, then CEO of Apple Computer, said that CDs would revolutionize the personal computer world. One of the first mass multimedia computers/adventure centers to win CDs was the Amiga CDTV (Commodore Dynamic Total Vision), later CDs began to be featured in the Panasonic 3DO and Amiga CD32 game consoles.

Beethoven's Ninth Symphony

Eyewitnesses and participants in the talks about the CD format testify that Philips and Sony did not have a single idea about the actual diameter of the disc until May 1980. From the looks of Sony engineers, a sufficient diameter of 100 mm, shards of vins allow you to miniaturize a portable programmer. In the light of Philips's great ceramics, the idea was to create a disc no larger than the diagonal size of a standard audio cassette (115 mm), which is a small success on the market. In addition, in this case, the disc fits the normal rows of linear dimensions of the DIN system.

The vice-president of the Sony Corporation Norio Oga, a musician, having taken into account that the disc is guilty of containing Beethoven's Symphony No. 9. And here, for good reason, on disks you can expand up to 95% of classic works. Later investigations showed that, for example, the ninth symphony of the viconnant philharmonic orchestra in Berlin, under the ceramics of Herbert von Karajan, had a small trivality of 66 marks. The symphony under the ceremonial work of Wilhelm Furtwängler, the victor at the Bayreuth festival - 74 hvilini became the most important vikonann. This was the main argument for the praised decision about the capacity of the disk.

“As in the majority of vipadkivs, the garna of history does not have anything good from real life. This story came from the pen of Philips PR,” says Kees Immink, a senior Philips engineer. Reality, to my mind, was different. Under Hannover, Philips is already preparing a line for the production of CDs at the PolyGram plant. AT minimal terms you can start the selection of disks with a size of 115 mm. Issuance of disks with a size of 120 mm, with significant losses of pennies at the same time, shards of bindings from the replacement of equipment. On the thought of Imminka, Sony did not want to accept the situation that Philips takes away the advantage of entering the market.

As it were not there, in the early 1980s, a residual disc size of 120 mm with a capacity of 74 audio recordings and a sampling rate of 44.1 kHz was inserted with a stroke of the pen of the greatest ceramics of firms. Other technical parameters were overprotected, vihodyachi z zgodzhenih danih.

Obligation of the data that are being saved

Compact discs are 12 cm in diameter and can hold up to 650 MB of information (or 74 sound recordings). However, beginning around the year 2000, more and more wide-ranging discs with a volume of 700 MB, which allow recording 80 pieces of audio, were later released as a disk with a volume of 650 MB. Zustrichayutsya and carry a volume of 800 megabytes (90 hvilin) ​​and more, but they can not read and bring CDs. There are also singles with a diameter of 8.9 cm [ ] (do not stray from minidiscs with a diameter of 8 cm), on which they fit close to 140 or 210 MB of data, or 21 audio files, and CDs, credit cards are guessed in the form (so-called sound discs-business cards).

The increase in the amount of saved information has become possible re-winning tolerances for the preparation of disks. So, for example, between the tracks following the ECMA-130 standard, set 1.6 ± 0.1 micrometers, the linear speed of the disc wrapping is 1.2 or 1.4 m / s ± 0.01 m / s throughput building 4.3218 Mbps. A capacity of 650 MB with a speed of 1.41 m / s and a capacity of 1.7 microns between tracks, and a capacity of 800 MB - a speed of 1.39 m / s [ ] and between the tracks 1.5 microns.

Technical details

Disc geometry

The compact disc has a polycarbonate backing of 1.2 mm and a diameter of 120 mm, covered with a thin metal ball (aluminum, gold, silver, etc.), protected by a lacquer ball, on which sound the graphic appearance of the disc is applied. The principle of reading through the lining allows even more simple and effective protection of the information structure and visualization of the outer surface of the disk. The diameter of the beam on the outer surface of the disk should be close to 0.7 mm, which increases the stability of the system before sawing and cutting. In addition, on the outer surface there is a collar ledge with a height of 0.2 mm, which allows the disk, placed on a flat surface, not to roll along the surface. At the center of the expansion disk there is an opening with a diameter of 15 mm (the diameter of a person's finger). The disk sleeve without a box becomes ~15.7 g. The disk sleeve of the original jewel-box (not slim) is ~74 g.

Coding information

The format for storing data on a disk is known as Red Book ("Chervona kniga"), which was distributed by Sony. It is possible to record sound on a CD in two channels with 16-bit Pulse Code Modulation (PCM) and a sampling frequency of 44.1 kHz. Zavdyaki korektsії pardons for the additional code Rіda - Solomon easy radial podryapini do not pour into the reading of the disk. In times of pardon, the value of the ICM signal, which could not be corrected by the pardon correction system, is replaced by approximate values, taken away for additional interpolation of the correct data. Philips also holds all rights to the "Compact disc digital audio" mark, the logo of the audio compact disc format.

Information structure

The information on the disc is recorded on a seemingly spiral track pit (eng. pit - burial), which was seen in a polycarbonate base. Skin pit may approximately 100 nm ridge and 500 nm rim. Dovzhina pita varies from 850 nm to 3.5 microns. Spaces between pits are called land (English land - expanse, base). The length of the tracks at the spiral becomes 1.6 microns. Drinks rose or smolder light that falls on them, and the lining - looks good. To that CD records - butt of diffraction gaps with a period of 1.6 microns. For alignment, DVD has a period of 0.74 microns.

Razrіznyayut disks less for reading ("aluminієві"), CD-R - for one-time entry, CD-RW - for one-time recording. Disks of the remaining two types are approved for recording on special drives that can be written. Some CD-players and music centers may not play such discs (the rest of the time, the players of other music centers and CD-players turn on CD-R/RW reading in their outbuildings).

Reading information

The data from the disc can be read with the help of a laser exchange with a long wind of 780 nm, which is carried out by a guided laser. The principle of reading information by a laser of all types of nose in the field of registering a change in the intensity of the incoming light. The laser light focuses on the information ball into a flame with a diameter of ~1.2 µm. If the light was focused between the pits (on the lens), then the primary photodiode registers the maximum signal. As light is consumed on the power supply, the photodiode registers less light intensity.

Vіdminnіst mіzh discs only for reading (CD) and discs that can be rewritten (CD-R/RW) are used in the way of molding pits. At the disc of Tilki for the reader of PITI IT IS IT IT IT REALFNETE (Phase Difraziyonoye), I will be the optical glybin of the skin of the skin menthi menthi divzhini hvitla laser, and the Phazi Phazi Khvili Mizh Svitel, Vidbimi . As a result, in the area of ​​the photodetector, the effect of destructive interference is observed and a decrease in the level of the signal is recorded. In the CD-R/RW slope, the spot is an area with more light, lower land (amplitude diffraction range). As a result, the photodiode also registers a decrease in the intensity of the beaten light of the disc. Dovzhina zhivlennya zminyuє as the amplitude, so the valority of the signal that is recorded.

The speed of reading / writing a CD is specified as a multiple of 150 Kb / s (tobto 153600 bytes / s). For example, a 48-speed drive ensures maximum read or write speed, which is 48 × 150 = 7200 Kb/s (7.03 Mb/s).

Clean disk

They also use cleaning CDs, on the working surface of which is attached an attachment for cleaning the sensor lens (div. photo).

Protection for copying

The specification of compact discs does not transfer the same mechanism of protection from copying - discs can be freely reproduced and replicated. Prote, beginning in 2002, various recording companies began to work and try to create CDs, protected from copying. The essence of the rich methods is to start up to the last pardon from the data, to record it on a disk, those on a per-bottom CD-player or a music center, the disk is reopened, but on a computer - nothing. As a result, such disks are far from being read by all other players, but in some computers - they are read; go out software security, which allows you to copy protected discs, etc. The recording industry continues to try new methods.

Philips has stated that discs that do not meet the Red book specifications are protected from the Compact disc digital audio mark.

For disks with data, various methods of copy protection are used, for example, the method of vimiryuvannya data positions, StarForce, SecurDisc and other technologies.

The CD-Audio format (before the advent of cd-grabers) was a kind of copyright protection and did not allow the extraction of audio files from a disk, for example, for the help of the Windows Explorer program.

Stages of CD production

1. Mastering is the process of preparing data for launch into a series.
2. Photolithography is the process of making a disc stamp. A ball of photoresist is applied to the cursed disk, on which the information is recorded. Photoresist is a polymeric light-sensitive material, a kind of light that changes its physical and chemical power.
3. Recording information. The recording is carried out by a laser exchange, the intensity of which is modulated by the information that is being recorded. For the creation of vitality, the intensity of the laser moves up, which leads to the destruction of the chemical bonds of the photoresist molecules, after which the wines “zadubue”.
4. Photoresist development. The surface of the photoresist is subject to etching (acid, puddle, plasma), in which there are those areas of the photoresist, which were exposed to the laser exchange.
5. Electrotype. The manifestations of the curses of the master disk are placed in a galvanic bath, where an electroplating of a thin nickel ball is carried out on its surface.
6. Stamping disks by casting method under a vice with a victorious stamp.
7. Filed mirror metal (aluminum, gold, silver and silver) to the ball on the information ball.
8. Applying sour varnish.
9. Application of a graphic image - a label (in English Label).

Burning to CDs

There are also discs that are recognized for recording in home minds: CD-R (Compact Disc Recordable) for one-time use and CD-RW (Compact Disc ReWritable) for one-time recording. Such disks contain special active material that allows recording/rewriting information. Separate discs with organic (mostly CD-R-type discs) and inorganic (mostly CD-RW-discs) active material.

When vikoristannі organic active material recording zdіysnyuєtsya ruynuvannya khіmіchіchnyh zv'yazkіv material, scho lead to yogo darkening (change the coefficient of fermentation of the material). When the inorganic active material is changed, the record is changed by the change in the coefficient of fermentation of the material as a result of the transition from an amorphous aggregate state to a crystalline state. In fact, and in another way, the recording is carried out by modulating the intensity of the laser.

For most people, such discs that are recorded are called "blanks". The process of recording is called "disappearance" (in English. To Burn) of the disc.

HD-BURN technology

The essence of the technology for recording a high-width field lies in the development of two new principles that allow you to record two more information on the primary media - a CD-R disc.

1. The life span on the disc changes to 0.62 µm. [ ] The life span of the sizable CD becomes 0.83 µm. [ ] This means that HD-BURN increases the disc capacity by 1.35 times. The 0.62 µm footprint was designed so that current DVD Video players and DVD-ROM drives could read HD-BURN discs after minor upgrades.
2. Another pardon correction system is being installed: CIRC (Cross Interleaved Reed Solomon Code) replacement RS-PC (RS-PRODUCT Code) with modulation 8-16. Tse allowed to increase the capacity 1.49 more times. For Sanyo's notice, the RS-PC pardon correction system is not only compact, but also effective, lower CIRC. [ ]

As a result, the capacity of one CD recorded in HD-BURN mode will double shift the capacity of a CD recorded in HD-BURN mode.

What is a CD

CDs were found in 1980. by engineers from Sony and Philips. On the fly, CDs were victorious for recording audiophonograms. The audio disc standard is called CD-DA (Compact Disk - Digital Audio, compact disc - digital audio). The headline of the CD before the traditional sound carrying (gramophone records, magnetic line) is in the supraphonic high quality sounding of the hour of the creation of phonograms. When a CD is being engraved, there is no laser contact between it and the disc. That's why in the phonograms, which are being created, there are more and more daily third-party noises, rustling and crackling, power in the sound records.

With the development of computer technology, compact discs began to win as an attachment for collecting information. Such discs were called CD-ROM (Compact Disk - Read-Only Memory, compact disc - permanent attachment). At a physical glance, I build a CD-ROM disc that is identical to an audio CD-DA-disc and looks like a less logical track structure (tracks).

A standard compact disc (CD) is made up of three balls: the basics that make it good. The base of the vikonan is made of translucent polycarbonate, on which the informational relief is pressed using the molding method. On top of the relief, a metal ball is sawn, which is used (aluminum, gold, silver, other metals and alloys). When the ball is covered with a ball of polycarbonate or neutral varnish - so that the entire metal surface of the bula is protected from contact with the outer core. On the zahisny ball, apply writings and little ones (by the method of shovkography with a special chemically neutral farboi). The thickness of the disc is 1.2 mm.

The information is recorded on the disk near a spiral path that goes from the center to the edge of the disk, de-rotting the grave (so called drink). The information is encoded by the number of pits (mentally - logical 1) and between them (mentally - logical 0). The distance between the turns of the track is selected from 1.4 to 2 microns, the standard is 1.6 microns. The information on the disk is encoded with the zavodovim code of Rіd - Solomon with victorious charguvannya - so that dribnі zboї when reading the tracks nіyak n_dbivayutsya on the reliability of the read information. The path can be without interruption LU. SO is divided into fragments (for example, sessions in multisession discs).

A compact disc is a plastic disc that has a round hole in the center. On a new laser for help, it is recorded and read optical information in digital format.

On the other hand, such discs were stoked for the preservation of digital music recordings, stink-knowing under the name "Audio CD". Ale, after a short period of time, disks were attached to save files in order to save digital information in a different format (video, text, software, music, pictures and photos). Such discs began to be called CD-ROM or "CD only for reading", even if you can write down information on it more than once, then it's worthless. Even through the rokіv z'yavlyayutsya disks, on yakі koristuvach mіg itself write information (CD-R), as well as disks with the possibility of overwriting (CD-RW), the information from which can be erased and recorded again.

Format files to be recorded on Audio CDs and on CD-ROMs. At zv'yazku z tsim, progravachi, recognized for reading only Audi CD, do not think it's possible to convert information from the disk to CD-ROM format, for which a special reading device is required.

The history of the CD begins in the 70s of the last century. Formerly vin appeared in 1979 roci. The cost of the joint venture of Sony and Philips. Company Sony developed a way to encode signals (similar to the one used by professional digital tape recorders), and for Philips it was a manufacturing process, in which the company's technology was put into production of laser discs.

On an industrial scale, CDs began to be released in 1982 at the German city under the auspices of the city of Langenhagen. The first music CD, which was the first to be sold, was presented in black 1982. On this disk of viishov, the album of the band "ABBA" - "The Visitors" is on sale. The great influx on the expansion of CDs is small and gigantic, like Apple and Microsoft.

True, yet another version of the similar CDs is credited to some American culprit James Russell from the Optical Recording Company. Already in 1971, the fate of wines showed their wines, which allowed them to save information. Russell's mailing list of optical discs became a bugbear to prevent sound-carrying heads from sound-carrying vinyl handkerchiefs from his favorite musical compositions. And for the last year Philips and Sony have repeated yoga wine.

Compact discs can be made with a thickness of 0.12 cm and a diameter of 12 cm. Viconan stink from polycarbonate with thin metal coatings (as a rule, silver, gold, aluminum thin) and varnish with a ball. On one disk of the disk, in a different way, information and images are applied, related to the mix (names of viconists, names of albums, tracks, logos, etc.).

W external side of the disk is a ledge, which operates the disk, and allows the working surface to fray from the recorded information. At the center there is a round opening, 1.5 cm in diameter. It is important to have a trochy CD less than 16 grams.

Music was recorded on CDs in Red Book format. It was dual-channel and low sampling rate of 44.1 kHz, as well as pulse-code modulation, which is 16 bits. Small podryapini, scho go to the edge of the disk in the center of the chi navpaki, do not add reading information from the disk. It is possible to start the code of Reed-Solomon, which gives the possibility of correcting the forgiveness of reading.

The information on the disk is recorded in tracks that are twisted around the form of a spiral. Pit mayut standard width and depth equal to 500 nm and 100 nm vidpovidno. And the axis along the length of the five varies one type of one and may have a range of variations from 850 nm to 3.5 microns.

Use the following types of discs: CD-ROM - only for reading, CD-R - for one-time recording, CD-RW - rewritable. To record information on CDs, special attachments are required to write (bring). There are also figured discs “Shape CD”, which are optical carriers of the CD-ROM type, like vicons in the form of stars, hearts, cars, cars, etc. As a rule, such discs are played like they carry video or audio information for people who are involved in show business. Shape CD was patented by German producer Mario Koss in 1995. Please respect that discs of the designated type are not vicorated in computer drives, since the stench is more fast, lower music, so the disc can be damaged and damaged by the drive.