optical discs CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-R, DVD-RAM, DVD-RW, DVD + RW, DVD + R, DVD + R DL

VARIETY OF OPTICAL INFORMATION MEDIA

CD-R became the very first among recordable optical media. They had the ability to record only once. The data was saved when the laser heated the working layer, causing its chemical reaction (at t? = 250? C). At this moment dark spots are formed at the places of heating. This is where the concept of “burn out” came from. On DVD-R discs, “burn through” happens in a similar way.

A bit different situation with CDs , DVDs and Blu-ray discs with rewriting function. On their surface does not form such dark points, because the working layer is not a dye, but a special alloy that is heated by a laser to 600? C. Then, the surface areas of the disk that fall under the laser beam become darker and have reflective properties.

At the moment, in addition to CDs, which can be considered the pioneers in a series of optical media, there are such discs as DVD and Blu-ray. These types of disks differ from each other. For example, capacity. Blu-ray disc holds data up to 25 GB, DVD - up to 5 GB, and CD - up to 700 MB in total. The next difference is the way data is read and written to Blu-ray drives. A blue laser is responsible for this process, the wavelength of which is one and a half times less than that of a red laser CD or DVD drive. That is why on the surface of Blu-ray discs, equal in size to other types of discs, you can record information many times larger.

FORMATS OF LASER DISCS

The above three types of laser discs can also be classified according to their formats:

1. CD-R, CD-RW discs are the same in volume (up to 700; sometimes 800MB, but such discs are not readable by all devices). They differ only in that CD-R is a one-time recordable disc, and CD-RW is reusable.

2. DVD-R, DVD + R format discs, as well as DVD-RW discs differ only in the ability to repeatedly rewrite DVD-RW discs, and the rest of the parameters are the same. 4.7 GB - the volume of a standard DVD and 1.4 GB - the volume of a DVD with a diameter of 8 cm.

3. DVD-R DL, DVD + R DL - dual-layer discs that can hold 8.5GB information.

4. BD-R Formats - Blu-ray single-layer discs, 25 GB in size and BD-R DL - Dual-layer Blu-ray discs, 2 times larger.

5. Formats BD-RE, BD-RE DL Blu-ray discs - rewritable, up to 1000 times.

Disks with “+” and “-” signs are a relic of formatted disputes. Initially it was thought that “+” (for example, DVD + R) was the leader in the computer industry, and “-” (DVD-R) was a quality standard for consumer electronics. Now almost all the equipment easily recognizes disks of both formats. None of them has clear advantages over each other. Materials for their production are also identical.

WHAT ARE OPTICAL DISCS FROM YOURSELF

The disc itself, which is used at home to record information, is no different in size from discs produced industrially. The structure of all optical media is multilayered.

• The basis of each - the substrate . It is made of polycarbonate, a material resistant to various external environmental influences. This material is transparent and colorless.
• This is followed by a working layer . In recordable and rewritable discs, it is different in composition. In the first - it is an organic dye, in the second special alloy, changing the phase state.
• Then comes the reflective layer . It serves to reflect the laser beam, and it may include aluminum, gold or silver.
• The fourth is a protective layer . The protective layer, which is a hard varnish, covers only CDs and Blu-ray discs.
• The last layer is the label . So called top coat of lacquer, able to quickly absorb moisture. Thanks to him, all the ink falling on the surface of the disc in the printing process, quickly dry.

THE PROCESS OF TRANSFERING INFORMATION TO A DISK

Now a drop of scientific theory. All optical media have a spiral track running from the very center to the edge of the disk. It is along this path that the laser beam records information. The spots formed during the “burning” by the laser beam are called “pitas”. The areas of the surface that remain intact are called land. According to the language of the binary system, 0 is “pit”, and 1 is “land”. When a disc starts to play, the laser reads all the information from it.

Pitas and Lands have different reflectivity, therefore, the drive easily distinguishes between all the dark and light areas of the disk. And this is the very sequence of ones and zeros inherent in all physical files. Gradually, it became possible to increase focusing accuracy due to the development of technologies that have reduced its wavelength from a laser beam. Now on the same area of ​​the disk as before, you can place a much larger amount of information, because the distance between the laser and the working layer is directly dependent on the wavelength. Shorter wave - shorter distance.

WAYS TO RECORD DISCS

• Recording with industrial production of discs is called stamping . In this way, a large number of discs are released with the recording of music, movies, computer games. All information that gets on the disc during stamping is a set of the smallest indentations. Something similar happened when records were made.
• Record the same disk in the domestic environment occurs using a laser beam. It is also called “ burned ” or “sliced”.

ORGANIZATION OF RECORDING PROCESS FOR OPTICAL INFORMATION MEDIA

Stage 1. Recognition of media type. We loaded the disc and wait for the recorder to give information about the appropriate recording speed and the most optimal laser beam power.

Stage 2 The program that controls the recording, makes a request to the recorder about the type of media used, the amount of free space and speed with which to burn the disc.

Stage 3 We specify all the necessary data requested by the program, and compile a list of files that require writing to disk.

4 stage. The program transmits the recorder all the data and monitors the entire process of "burning".

Stage 5 The recorder sets the power of the laser beam and starts the recording process.

Even for carriers of the same format, the recording quality can be completely different. To ensure the quality of the recording is high, you should pay attention to the speed specified in the recording. There is a “golden rule” - fewer errors at lower speeds and vice versa. A significant role is played by the recorder itself, namely, its model.

SIGNATURE ON OPTICAL DISKS

A disk on which some information has appeared, it is desirable to sign right there, in order to avoid confusion. This can be done in different ways:

• printing text on blanks, the surface of which is varnished and allows you to print texts and images using an MFP with a special tray.
• with the help of a recorder, with the support of special technologies that carry out the application of text and monochrome images on a special surface. The cost of such disks can have 2 times the cost of simple disks;
• self-signed signature manually (with a special marker);
• technology LabelTag - text is applied directly to the disk work surface. The inscription can not always be well read;
• stickers printed separately on any of the printers. Their use is not welcome, because they can damage the surface of the disc, come off at the time of its playback.

DURATION OF THE STORAGE OF OPTICAL INFORMATION MEDIA

On the labels of new discs, you can see the term indicating how much data can be stored on this carrier. Sometimes this figure corresponds to 30 years. In reality, such a term is almost impossible. During its existence, the disk can be subjected to various impacts and damage. If it was recorded at home, its shelf life is reduced even more. Only perfect storage conditions will keep all data on disks safe and sound.

CD-DA (Compact Disc - Digital Audio), were developed by Sony and Philips in 1982. The wavelength of the laser in the air - 780 nm. Diameter 120 mm (information zone from approximately 50 mm to 116 mm) or 80 mm. Thickness 1.2 mm. Weight - from 14 g to 33 g (DVD - from 13 to 20 g). The chain of grooves (pits) is arranged in a spiral as in a record, but in a direction from the center (in fact, CD is a sequential access device with an accelerated rewind). The interval between the turns is 1.6 μm, the pit width is 0.5 μm, the depth is 0.125 μm (1/4 of the wavelength of the laser beam in polycarbonate), the minimum length is 0.83 μm. The volume is 74 minutes of sound (44.1 kHz, 16 bits, PCM, big-endian) or 650 MB of data (333000 sectors of 2048 bytes), for 80 mm - 21 minutes (185 MB). The sampling rate was chosen to make copying to DAT (48 kHz) difficult. There are modifications in 80 minutes (700 MB), 90 minutes (791 MB) and 99 minutes (870 MB). A constant linear speed of moving the carrier relative to the head (1.25 m / s) is provided, respectively, the rotational speed changes when reading different parts of the disk (from 500 rpm to 200 rpm), which increases the access time (it is necessary to accelerate and slow down the rotation of the disk) . The nominal (1x) data transfer rate is 150 KB / s (176400 bytes / s of audio or raw data, 4.3 Mbps of “physical” data).

• CD-DA (Digital Audio, Audio CD). IEC 908. Red Book. 1982
• CD-ROM. Yellow Book (1983). ISO / IEC 10149 (1989). ECMA-130 (1988, 1996). Describes the physical CD format for data storage.
• CD-I (Interactive) - multimedia discs for consumer devices (including MPEG video). Green Book.
• CD-ROM XA. 1989 Allows you to alternate data of different types (data, graphics, video, sound, text) on one track. Multisession
• PhotoCD (above CD-ROM XA and Orange Book). 1990. Attempt by Kodak to isolate itself from competitors through its own CD-ROM format. Multisession
• VideoCD (MPEG-1 over CD-ROM XA, 352x280x25, not to be confused with analogue CD-Video). White Book.
• CD-Bridge, CD-I Bridge. Combination and unification of CD-DA, CD-ROM XA, CD-I, PhotoCD, VideoCD.
• SVCD (Super Video CD, MPEG-2, 2.6 Mbit / sec).
• CD-MO, CD-WO (CD-R), CD-E (CD-RW). Orange Book. 1990. Defines how to record CDs described in red, green, yellow and white books. Hybrid disc - the first session is stamped, the remaining CD-Rs
• CD Text (proposed by Philips).
• CD-Graphics (CD-G, CD + G). Used in karaoke.
• CD Extra (CD Plus). The first session of the disc is designed for music players, the rest for reading a CD-ROM (CD-ROM XA). Blue Book. Stamped multisession.
• CD-MRW (Mount Rainer). Manage bad blocks for CD-RW and some other improvements that allow you to use it as a direct access device.
• DVD-ROM. DVD Forum. 1995 year. ECMA-267 (120 mm), ISO / IEC 16448. ECMA-268 (80 mm), ISO / IEC 16449.
• DVD-Video. Video based on DVD-ROM. MPEG-2 MP @ ML (720x576x25i, Dolby Digital Sound or MP2, 133 minutes).
• DVD-Audio. DVD-ROM based sound (up to 24 bit, up to 192 kHz). DVD-AudioV (with additional information).
• DVD-R (A), DVD-R (G). 1997. ECMA-279 (outdated version 1.0). ECMA-359, ISO / IEC DIS 23912 (version 2, 2004).
• DVD-RAM. Approved by the DVD forum in 1997. ECMA-272, ECMA-273 (outdated version 1.0), ISO / IEC 16824, ISO / IEC 16825. ECMA-330, ECMA-331, ISO / IEC 17592, ISO / IEC 17594 (version 2 ).
• DVD-VR. DVD-RAM based video. Incompatible format with DVD-Video.
• DVD-RW (DVD-R / W, DVD-ER). 2000. ECMA-338, ISO / IEC 17342 (version 2, 2002)
• DVD + RW. 2001. ECMA-274 (outdated version 1.0), ISO / IEC 16969. ECMA-337, ISO / IEC 17341 (version 2, 2003). Write speed up to 4x.
• DVD + R. Write speed up to 8x. ECMA-349, ISO / IEC 17344 (version 2, 2004).
• DVD + R9. Double Layer. Write speed up to 2.4x
• DVD Forum promises DVD-R DL.

• A stamped CD-ROM is polycarbonate, coated on one side with a reflective layer (aluminum or - for critical applications - gold) and a protective varnish with printed label. This side should be protected from mechanical damage, since varnish is very vulnerable. Minor damage on the other side is less significant (while maintaining transparency), because Optics are not focused on the surface of the disk. Changing the reflectivity is carried out by stamping depressions in the metal layer. Storage time is estimated at 10 years.
• CD-R (CD-WORM) - instead of the aluminum reflecting layer, a gold or silver alloy is used, in front of which a layer of heat-sensitive paint is applied. During recording, the area (pit) is irradiated with a laser and, when heated, the paint expands and begins to scatter light in a manner similar to a recess in the aluminum reflective layer. It is impossible to keep unrecorded discs for a long time (no more than 5 years) and keep in the sun. Blue and green cyanine (cyanine) blanks have an estimated (no one has yet tested in practice;) a storage time of 75 years, phthalocyanine (phtalocyanine) - 200 years. Phthalocyanine is more resistant to heat and light, but requires careful tuning of the laser power. On the top layer of polycarbonate there is a spiral marking track (pregroove) containing ATIP codes - the required laser power, the possible recording speed and time codes for each frame, as well as information about the media (information is determined by the manufacturer of the matrix, the manufacturer of the disk can use the matrix not for its intended purpose : pour another paint, etc.):
  • matrix manufacturer (not disk!)
  • type of workpiece (CD-R, CD-RW)
  • paint type (die type), more precisely, what the matrix manufacturer supposed
  • the number of blocks available for writing (determined by the matrix)
  • allowable write speed (min, max)
  • recommended laser power
  • audio is a higher quality disc (and a price that includes a special tax) that you can write CD-DA on; household recorders record only on such blanks
• CD-RW (CD-E). Modifications: 1x-4x (Multi Speed), 4x-12x (High Speed, 10x written on the box, self-identified as 8x, but written to 12x!), 12x-24x (Ultra High Speed), for high-speed PCA disks is offset. so old (4x) devices do not recognize the new disk (4x-10x). A mechanism is used to transform the crystalline (high reflectivity) states of the recording layer into amorphous (low reflectivity) and back under the influence of point heating by a laser. Erase power is less than write power. It is impossible to bend strongly (the amorphous state is semi-fluid). Shelf life - 10 years. Record cycles - 1000 (some manufacturers swear that 100000). I note that the PCA is designed for 100 entries. The reading cycles are 100,000. The reflection level is lower than that of the stamped one; therefore, they are read only by modern CD-ROM devices with automatic gain control (MultiRead marker; almost everything, starting from 8x), usually slower than CD-ROM or CD-R. Also has a pre-extruded markup track with ATIP.
• DDCD (Sony) - reduced distance between turns and reduced pit size. 1.3 GB.
• ML-ROM, ML-R, ML-RW (TDK) - 3 bits per pit. Capacity and speed tripled. 120 mm disks - 2 GB, 80 mm - 650 MB, 60 mm - 200 MB.
• DVD-ROM. The carrier is similar to a CD-ROM (120 mm and 80 mm), but the laser wavelength is reduced from 780 nm to 635/650 nm, which made it possible to reduce the distance between the turns to 0.74 μm and the size of the pit to 0.14 μm. Interestingly, the change in wavelength led to the fact that DVD devices read CD-RW better than CD-R - look for the words "dual laser". The narrower focusing of the beam made it possible to reduce the thickness of the disc to 0.6 mm and glue them together in two, thus making double-sided discs, increasing the capacity from 4.7 GB (Type A, DVD-5, SS / SL, 120 mm) to 9.4 GB (Type B, DVD-10, DS / SL). Hereinafter, in the story of a DVD, 1 GB equals a billion bytes, not 2 ^ 30. Data on each side can be stored in one or two layers (focusing the beam at different depths), thus increasing the capacity to 8.5 GB (Type C, DVD-9, SS / DL) or 17 GB (Type D, DVD-18, DS / DL). Another system of channel coding and correction codes, but the same disgrace with a spiral track, constant linear speed and interlaced video (basic reading speed - 1350 KB of data per second; 3.49 m / s for single-layer and 3.84 m / s for double-layer discs; 26.16 channel Mb / s). Spiral double-layer disc can twist in one direction (PTP) or in opposite directions (OTP).
• DVD-R. Unilateral (4.7 GB, 1S; first version - 3.95 GB) and double-sided (9.4 GB, 2S). Thermal paint as in CD-R, but of a different type. Read on any DVD-ROM. DVD-R (A) - can only be recorded on professional equipment. DVD-R (G) - can be recorded only on consumer equipment, protected from copying to them. Lasers with different wavelengths (635 and 650 nm) are used for recording on A and G discs. The maximum recording speed is up to 16x (written on the box, but the device can have its own opinion).
• DVD-RAM. Single and double sided (type 1 cartridges only). The first version is 2.6 GB per side, the second is 4.7 GB. Used phase change as in CD-RW in combination with MO, Reflectance is lower than that of DVD-ROM. The version for recording video is called DVD-VR. Instead of CLV, Zone CLV is used. Not only pregroove is printed, but also sector headings. Handling bad blocks is provided. Placed in openable (type 2) or solid cassettes (type 1) or without them (read only). A special cassette (type 3) is provided for placing discs in it. When removing a disc from a cassette of type 2, it is necessary to pierce a hole that allows the device to unambiguously determine that the disc was removed or replaced. Some devices refuse to write to such discs. Up to 100 thousand rewrite cycles. Storage time is 30 years. Direct access to both reading and writing. Formatting is required before use. Usually not readable on DVD-ROM, DVD-R, DVD-RW, DVD + RW. When recording data, a second pass is required for verification, which reduces the recording speed to 700 kB / sec. Manufactured since 1998.
• DVD-RW. 4.7 GB Designed based on DVD-R, but using a phase change like a CD-RW. Отражающая способность ниже, чем у DVD-ROM (некоторые устройства путают его с двухслойным DVD-ROM), кассета не нужна, читаются почти на любых DVD-ROM. Версии 1.0 (впечатанный lead-in), 1.1 и 1.1B (каждая болванка имеет уникальный ключ для шифрования) одинаковой емкости. Максимальная скорость, определённая в стандарте - 4x (бывают устройства 8x).
• DVD + RW. The first version is 3 GB, the second is 4.7 GB. Used phase change as in CD-RW. Single-sided (type S) and double-sided (type D). Allows you to overwrite part of the data without affecting others (for example, overwriting a poorly recorded sector). No cassette required. For video, CLV is used, for data - CLV or CAV (not readable on DVD-ROM). Reflectivity is lower than DVD-ROM. Not supported by DVD-forum. Up to 1000 rewrite cycles. The maximum speed defined in the standard is 4x (there are 8x devices).
• DVD + R. Coined DVD alliance to complete the picture. Format from DVD + RW, chemistry from CD-R. Single-sided (type S) and double-sided (type D). The maximum speed defined in the standard is 8x (there are 16x devices).
• DVD+R9. Двухслойный DVD+R. 8.5 GB. Безумно дорогие. Максимальная скорость, определённая в стандарте - 2.4x (бывают устройства 4x).
• Divx (не путайте с Divx;-) ). Технология взимания арендной платы за просмотр DVD-Video: встроенный в DVD-player модем дозванивается до владельца лицензии и получает ключ на использование диска в течении 48 часов. Такая гадость не могла жить долго.

CD может иметь bar code (вертикальные штрихи), прожженный лазером в BCA (burst cutting area, внутреннее кольцо перед lead-in), используемый для серийного номера, но мне не встречались устройства, которые умеют его читать. DVD может иметь BCA только на односторонних дисках. Для повышения надежности используются коды EDC и ECC.

SID (Source Identification Code) для DVD Audio. Состоит из двух частей: Mastering Code (строка "IFPI" и 4-символьный код, выжигается лазером на штампе) и Mould Code (строка "IFPI" и 4-символьный код, гравируется на форме), которые отпечатываются на противоположных сторонах подложки на внутреннем кольце (до BCA). Должны читаться невооруженным глазом. В этом же кольце могжет быть напечатана и другая информация, требуемая местными законами.

Не рекомендуется наклеивать что-либо на поверхность диска (нарушите балансировку, а скорость вращения 5000 об/мин; к тому же некоторые виды клея растворяют защитный лак; а эти гадкие воздушные пузыри?) или надписывать его (промнете защитный слой или чернила его растворят, графитовая пыль тоже не подарок). Единственным безопасным методом маркировки является печать на специальном принтере. Кстати, простейший способ уничтожить информацию на CD - это содрать присохшую наклейку. Мыть можно теплой водой с мылом (никаких органических растворителей, спирта и прочей химии).

Торговая марка, под которой продаются заготовки, не всегда (точнее, почти всегда не) соответствуют их реальному изготовителю. Даже по ATIP вы можете узнать лишь изготовителя матрицы, но не конкретный завод, использующий эту матрицу. Примеры ATIP дисков различных типов, размеров и скоростей записи. Большой обзор CD-R заготовок, продающихся на московском рынке, можно найти на IXBT.

Поверхность диска разделена на области:

• PCA (Power Calibration Area). Используется для настройки мощности лазера записывающим устройством. 100 элементов.
• PMA (Program Memory Area). Сюда временно записываются координаты начала и конца каждого трека при извлечении диска из записывающего устройства без закрытия сессии. 100 элементов.
• Вводная область (Lead-in Area) - кольцо шириной 4 мм (диаметр 46-50 мм) ближе к центру диска (до 4500 секторов, 1 минута, 9 MB). Состоит из 1 дорожки (Lead-in Track). Содержит TOC (абсолютные временные адреса дорожек и начала выводной области, точность - 1 секунда).
• Область данных (programm area, user data area).
• Выводная область (Lead-out) - кольцо 116-117 мм (6750 секторов, 1.5 минуты, 13.5 MB). Состоит из 1 дорожки (Lead-out Track).

Двоичный нуль представляется в виде отсутствия изменений в отражающей способности поверхности диска (длина участка определяет число нулевых бит), единица - в виде изменения отражающей способности на рассматриваемом участке.

Каждый байт данных (8 бит) кодируется 14-битным символом на носителе (кодировка EFM). Символы отделяются 3-битными промежутками, выбираемыми так, чтобы на носителе не было более 10 нулей подряд.

Из 24 байтов данных (192 бита) формируется кадр (F1-frame), 588 битов носителя, не считая промежутков:

• синхронизация (24 бита носителя)
• символ субкода (биты субканалов P, Q, R, S, T, U, V, W)
• 12 символов данных
• 4 символа контрольного кода
• 12 символов данных
• 4 символа контрольного кода

При декодировании могут использоваться различные стратегии обнаружения и исправления групповых ошибок (вероятность обнаружения против надежности коррекции).

Последовательность из 98 кадров образует сектор (2352 информационных байта). Кадры в секторе перемешаны, чтобы уменьшить влияние дефектов носителя. Адресация сектора произошла от аудиодисков и записывается в формате A-Time - mm:ss:ff (минуты:секунды:доли, доля в секунде от 0 до 74). Отсчет начинается с начала программной области, т.е. адреса секторов вводной области отрицательные. Биты субканалов собираются в 98-битные слова для каждого субканала (из них 2 бита - синхронизация). Используются субканалы:

• P - маркировка окончания дорожки (min 150 секторов) и начала следующей (min 150 секторов).
• Q - дополнительная информация о содержимом дорожки:
  • число каналов
  • данные или звук
  • можно ли копировать
  • признак частотных предискажений (pre-emphasis): искусственный подъем высоких частот на 20 дБ
  • режим использования подканала
    • q-Mode 1: во вводной области здесь хранится TOC, в программной области - номера дорожки, адреса, индексы и паузы
    • q-Mode 2: каталоговый номер диска (тот же, что на штрих-коде) - 13 цифр в формате BCD (MCN, ENA/UPC EAN)
    • q-Mode 3: ISRC (International Standard Recording Code) - код страны, владельца, год и серийный номер записи
  • CRC-16

На самом деле все еще "интереснее", т.к. в дополнение к секторам определяются секции того же полезного размера, но с несовпадающими границами, причем часть адресов является адресами секторов, а другая - адресами секций. Но об этом лучше сразу забыть ;)

A sequence of sectors of the same format is combined into a track (track) from 300 sectors (4 seconds. See subchannel P) to the entire disk. A disc can have up to 99 tracks (numbers from 1 to 99). A track may contain service areas:

• pause - only subchannel information, no user data
• The pre-gap is the beginning of the track, does not contain user data and consists of two intervals: the first one with a length of at least 1 second (75 sectors) allows you to “settle out” from the previous track, the second one with a length of at least 2 seconds sets the format of the track sectors
• post-gap - the end of the track, does not contain user data, at least 2 seconds long

The introductory digital domain must end with post-gap. The first digital track should start from the second part of the pre-view. The last digital track should end with post-gap. Output digital domain does not contain pre-view.

CD-DA. Each sector contains 588 signal samples (PCM, 2 channels, 16 bits). Samples are spread across the sector to reduce the impact of data dropout.

CD-ROM Mode 0: not available.

CD-ROM Mode 1: synchronization, block address, 2048 bytes of user data, EDC (CRC-32), ECC (276 bytes, two sums: P and Q - not to be confused with subchannels!), 8 bytes of zeros.

CD-ROM Mode 2: synchronization, block address, 2336 bytes of user data without additional protection.

CD-ROM XA Mode 1 is the same as CD-ROM Mode 1.

CD-ROM XA Mode 2 Form 1: synchronization, block address, CD-I subtitle (8 bytes, defines the type and format of user data - audio, video, data), 2048 bytes of user data, EDC (CRC-32), ECC ( 276 bytes, two sums: P and Q - not to be confused with subchannels!).

CD-ROM XA Mode 2 Form 2: synchronization, block address, subtitle CD-I (8 bytes), 2324 bytes of user data, EDC (CRC-32).

CD Text (text - author, title - is recorded in the subchannels RW).

CD-Graphics. RW subchannels are used to record graphics.

CD-R and CD-RW. When the disc is closed (finalizing, fixating), the output area is recorded immediately after the program area, after which the input area containing the TOC is recorded. If the disc was not recorded at one time, then the TOC is formed from PMA. The laser can not turn on and off instantly, so the data "burned" during the transition process can not be read (because of this there is a problem of emptying the buffer). Unused spaces are left at the joints. Recording methods:

• disk-at-once (DAO). Can be used as a master disk.
• session at once (SAO).
• track-at-once (TAO).
• Batch write. Before the package there should be one linking (link) sector and 4 input (run-in). After the package, 2 output sectors (run-out) should be recorded. Disk space is reduced by 7 sectors per packet. Package length can be fixed within the track or variable. By pre-formatting packages of fixed length, you can organize a CD-RW disc as a direct access device (it takes a lot of time and space on auxiliary sectors - 120MB). When using variable-length packages, the space is not cleared when a file is deleted.

Multisession (multisession) record. The lead-out area of ​​the second session is recorded after the lead-out area of ​​the first session, then the data area, etc. The size of the exit zone for the second and subsequent sessions is reduced to 2,250 sectors (0.5 minutes, 4 MB). A session is called closed if its data area is framed by an input and output area. Unclosed sessions can only be read by recording devices (access to PAM is required). The pointer in the session TOC to the output area may contain either the address of the output area of ​​the session (closed disk), or the address of the input area of ​​the next session. Recording is limited by disk space, space in PMA and the number of tracks (tracks are numbered all over the disk from 01 to 99). A session can be independent (TOC indicates only tracks within a session) or related (TOC contains addresses of tracks from previous sessions). Sessions can also be linked at the file system level. The session mechanism allows you to "change" a CD-R by writing a new session.

CD-RW erasure: full and fast (TOC only). If the disk is so damaged that it is impossible to perform erasing, then you can try to erase it with ultraviolet light (or sunlight).

It is rumored that some devices record on each disk the Recorder Unique Identifier (RID): the device manufacturer's identifier, model number and serial number (as I remember, typewriters were recorded in the USSR;).

There are two methods: purchase of a blank marked up (pregroove) for a more standard volume due to closer spiral turns or use of lead-out for these areas and some space behind it. You can use both methods at once. CD-R blanks come in 80 minutes (700 MB), 90 minutes (791 MB) and 99 minutes (870 MB), CD-RW blanks have been encountered (so far?) Only 700 MB. Both methods violate the standard. Either the recording device or the reading device may not be able to work with a closer spiral (see the table of compatibility of recording devices and supported write speeds). For example, my Plextor PX-W1610TA has to set the write speed for 700 MB of CD-RW blanks to 8x (and this does not always help). Lack of space for a lead-out can lead to abnormal termination of the recording (in this case, the TOC will not be written and the disk will be unreadable - write it in DAO mode and the TOC will always be, the -dao switch in cdrecord), the program will fail to start recording (use the -ignsize switch in cdrecord) or the inability to read the resulting disk (especially in older devices, nothing will help here). Another problem is caused by the method of addressing blocks on a disk (the address is written in the format MM: SS: FF relative to the beginning of the data region): first, 2 decimal digits are allocated to the number of minutes, which immediately limits the amount to 99 minutes, second, blocks Lead-in addresses are negative numbers for which addresses are reserved starting at 80:00:00. That is why in the ATIP even the 99-minute blanks are imprinted length 79:59:74. And what the recording device, program or reader will do when it encounters two blocks with the same address is unknown. In general, if your data is dear to you - do not be greedy, write down this 700 MB for 2 blanks.

The disk information area is divided into an input zone (lead-in zone), a data zone (data zone), and a lead zone (lead-out zone). On a double-layered disk with opposite spirals (OTP), each side contains only one information zone on both layers. An intermediate zone (middle zone) is used to move the beam from layer to layer. Sectors are addressed sequentially throughout the information zone (LBA). No tracks, pauses, gaps, subchannels and A-time addressing. Uniform data format: farewell modes and forms.

The structure of the introductory zone:

• Initialization zone The number of sectors is not defined by the standard, but the last sector should have the number 0x02EFFF.
• Reference Code. 32 sectors, starting at address 0x02F000, containing the standard pattern.
• Buffer zone 1. 480 sectors, starting at address 0x02F020.
• Control data zone 3072 sectors, starting at address 0x02F200. Contains 192 copies of the following information:
  • physical format description (2048 bytes):
    • standard version number (4 bits)
    • disc category: read only, rewritable (4 bits)
    • maximum access speed: 2.52 Mb / s, 5.04 Mb / s, 10.08 Mb / s (4 bits)
    • physical disk size: 80 mm, 120 mm (4 bits)
    • layer type: read only, rewritable (4 bits)
    • PTP or OTP
    • single or double sided disc
    • track width: 0.74 microns (4 bits)
    • pit length: 0.133 or 0.147 micron (4 bits)
    • distribution of the data zone: the address of the first data sector (0x030000 for DVD-ROM, 0x031000 for DVD-RAM), the address of the last data sector (for DVD-RAM it is fixed), the address of the last data sector on layer 0 for OTP mode.
    • for DVD-RAM: can I burn to disc without tape?
    • for DVD-RAM: read and write powers, speeds and time intervals
    • NBCA (Narrow Burst Cutting Area)
  • Disc maker information: not standardized (2048 bytes).
  • manufacturer information content: not standardized (14 * 2048 bytes).
• Buffer zone 2. 512 sectors, starting at address 0x02FE00.

Binary zero is represented as no change in the reflectivity of the disk surface (the length of the section determines the number of zero bits), the unit - in the form of changes in the reflectivity in the area under consideration.

The physical sector contains 4836 bytes. Of these, 104 bytes of synchronization and 4732 bytes of channel data.

For DVD, in contrast to CD, the encoding is 8-bit bytes of the recording frame with 16-bit channel symbols without RLL (2.10) spaces (the encoding itself provides no more than 10 consecutive zeros, but knowledge of the subsequent character is sometimes required to decode a byte).

Bytes of 16 frames are mixed similarly to CD to reduce the impact of local carrier defects. Each such “large” block (ECC block) contains 4832 bytes of ECC and 33024 (2064 * 16) bytes of the data frame.

The data frame DVD-ROM, DVD-RAM, DVD-R, DVD-RW (Data Frame) consists of:

• data identification (ID)
  • sector number (24 bits). The same rake, as with standard ATA - what to do, when the size of the next version of DVD will exceed 34 GB?
  • layer number (1 bit)
  • read only or writeable (also a sign of the binding sector)
  • zone type: data, lead-in, lead-ut, middle (2 bits)
  • reflectivity of the carrier (more or less than 40%)
  • track tracking method: by pit or printed track - groove (1 bit)
  • sector format: CLV or zoned (1 bit)
• data identification checksum (IED)
• copyright management information (6 bytes); not used for dvd ram
• 2048 bytes of user data (Main Data)
• data checksum

Thus, the storage of 2048 bytes of user data consumes 4836 bytes of the physical sector (mixed and spread). This is significantly better than approximately 8415 bytes in the case of a CD-ROM.

NBCA is a narrow ring to the introductory zone on which the code is marked with vertical bars (and what is written there?).

DVD-RAM contains both printed (embossed) and rewritable data. The first 5 zones of the lead-in zone are printed: the initialization zone, the reference code, the first buffer zone, the control data and the second buffer. In the remaining zones, the spiral is formed by an etched groove (groove), and the recording is made both in the grooves (groove track, groove sector), and between them (land track, land sector). The spiral is divided into virtual tracks (360 ° rotation). In the introductory zone, in addition to the 5 zones defined by the DVD-ROM standard, there is a junction zone (gap between printed and rewritable regions, empty space without sectors), protection zone 1, disk testing area, disk testing area, protection area 2, reserve zone, DMA 1 (defective block management area), DMA 2. Address 0x030000 has not the first sector of the data zone, but the first sector of the first protection zone. The lead-out zone consists of a DMA 3, DMA 4 zone, a protection zone 1, a zone for testing a disk, a zone for testing a disk drive, a protection zone 2, a reserve zone. The first sector of the data zone has the address 0x031000. Each track of the introductory zone consists of 18 sectors. The rewritable region is divided into 24 subzones divided by guard zones. The subzone is framed by protective zones and has an area of ​​spare blocks. LSN (Logical Sector Number) addressing is entered, so all sectors with user data have consecutive numbers starting from 0. Within each subzones, the tracks consist of the same number of sectors (from 17 to 40), but these sectors contain 2697 bytes (data format the physical sector of the DVD-ROM is framed with any additional information, and the title is imprinted during manufacture). The helix itself has a sinus-like shape, with the zero phase located on the border between the sector header and the rest of it (now I understand why DVD-RAM blanks are so expensive;). The contents of all DMA zones are identical and contain information about the formatting of the disk, the primary list of defects (detected during formatting) and the secondary list of defects (detected during operation).

The DVD-R before the lead-in zone contains the R-Information zone, which is divided into the PCA (Power Calibration Area, 7088 sectors, 256 for the disc manufacturer) and RMA (Recording Management Area) familiar with the CD-R.

The lead-out zone follows the data zone, but cannot begin earlier than some boundary. Recording mode - CLV. In incremental mode, 3 methods of linking old and new pieces can be used (who chooses?):

• 2K loss
• 32K loss
• without loss

The size of the initialization zone (in Lead-In) is determined rigidly and it is divided into the initialization zone itself (45,664 sectors of zeros), buffer zone 0 (512 sectors of zeros) and the information zone about the physical format, which consists of 3,072 sectors containing 192 repetitions of 16 sectors (in fact, the same information as in the control data zone, but not filled by the manufacturer of the blank):

• non-standardized manufacturer information
• standard version number (4 bits)
• disc category: read only, rewritable (4 bits)
• maximum access speed: 2.52 Mb / s, 5.04 Mb / s, 10.08 Mb / s (4 bits)
• physical disk size: 80 mm, 120 mm (4 bits)
• layer type: read only, rewritable (4 bits)
• PTP or OTP
• single or dual layer disc
• track width: 0.74 microns (4 bits)
• pit length: 0.133 or 0.147 micron (4 bits)
• distribution of the data zone: the address of the first data sector (0x030000 for DVD-R), the address of the last data sector
• NBCA availability
• address of the first sector of the current output boundary zone and the next input boundary zone

The boundary zones are designed to prevent ordinary DVD-ROM devices from reading data from still unrecorded parts. Each takes from 12 MB to 92 MB depending on the location.

The control data zone is embossed or pre-recorded, therefore framed by binding to the previous and subsequent information. The buffer zone 2 has been renamed to the zone of additional boundary (it contains one more variant of information about the physical format).

A control spiral track is squeezed out on a DVD-R, which also contains data (blocks are numbered down) - Unrecorded Zone (almost undead;):

• restrictions on the equipment used in writing (special drives, restricted use)
• physical characteristics of the disk: diameter, speed, spot size, wavelength, etc.
• maximum writeable address
• suggested values ​​for OPC (Optimum Power Calibrate)
• write strategy (duration of laser pulses and pauses between them for different circumstances) and the parameters of its adaptive adjustment (we need to melt the paint, but not evaporate)

The data zone can be divided into subzones (RZone, 2102), which can be open (no more than 2) and closed (completed). The unused and unreserved part is called the invisible RZone.

RMA format

• recorder manufacturer ID
• model
• serial number (here it is happiness!)
• Information about each recording session (RMD)
  • disk status: empty, recording in DAO mode, complementary recording, closed
  • OPC information for 4 devices: manufacturer, serial number, model, write strategy, power, time, PCA sector, OPC result
  • addresses of the first sectors of the output boundary zones
  • amount of rzone
  • the number of the first open RZone
  • number of the second open RZone
  • addresses of the first sectors of each RZone and the last recorded address in it

The data structure is very similar to the DVD-R structure. Recording mode - CLV.

The control data zone and buffer zone 1 are extruded or prerecorded. The control data zone does not consist of 192 identical copies, but only of 176, followed by 16 servo control units (not defined in the standard).

The extruded control path (Unrecorded Zone) additionally contains suggested OPC values ​​and strategies for erasing. In the PCA, for the disk manufacturer, 16 sectors are allocated around 256.

The format of information on each recording session (RMD) is different for different recording modes (DAO, incremental recording, limited rewriting) and contains data on the disk status (empty, complementary recording, DAO, closed after the complementary recording, minimally cleared, a failure occurs formatting, empty and write-protected, DAO and write-protected, complementary recording and write-protected, closed after complementary recording and write-protected, minimally cleared and write-protected, various limited rewriting modes), copy of information from the embossed track, OPC information for 4 devices (similar to DVD-R, but supplemented with information about erasing), number of changes, number of erasures, RMD bitmap defectiveness bitmap, type of erasing now and current position, type of formatting happening now and current position, addresses and status of input and output boundaries (up to 16 pieces), the number and boundaries of RZone (up to 16 pieces), bitmaps of defectiveness of blocks.

Types of erasure

• Minimal cleaning (the introductory zone and the R-Information zone are erased, except for the PCA, the introductory zone of the RMA and the first 6 RMD
• whole disk (erases all information zone and R-Information zone, except for PCA, introductory RMA zone and 6 first RMDs)
• RZone tail (from the beginning to the last recorded RZone block)
• boundaries of the uncovered zone (last entrance and last exit borders)
• last restricted area

Formatting types (everything is filled with zeros, except for the input zone, output zone, input boundary, output boundary)

• full
• border shift (from the beginning of the last output border, the size is set)
• adding a border (from the beginning of the newly created input border, the size is set)
• fast shift (the area is in an intermediate state)
• quick add (region appears in intermediate state)
• closing the border (transfer area from intermediate to closed state)

States of limited area:

• intermediate - the data is recorded, and the boundaries are not formed
• незавершённое - данные и входная граница оформлены, а выходная - нет
• закрытое - данные и границы записаны

Каждая заготовка DVD-RW 1.1B имеет уникальный (64 бит) идентификатор (механизм защиты CPRM). Содержимое диска может шифроваться (C2) по ключу, генерируемому из этого идентификатора, поэтому простое копирование даст нечитаемые данные (фильмы).

Режим записи - CLD (Constant Linear Density), устройство может реализовать CAV. Скорость записи - до 4x. Формат фрейма данных и его кодирование совпадает с DVD-ROM. Выбранный метод записи позволяет произвольно записывать и перезаписывать ECC блоки (32 КБ).

Информационная зона делится на вводную зону, зону (пользовательских) данных (2295104 сектора) и выводную зону. Все их можно перезаписывать, чистая болванка не содержит ничего. Первый сектор зоны данных имеет адрес (PSN) 0x30000. Логический адрес (LSN) этого сектора равен 0.

Запись идёт по выдавленной канавке. Канавка имеет форму спирали, на которой с помощью небольших отклонений записана информация об адресах блоков, которые должны быть размещены в данном месте (ADIP - Address-in-Pregroove). На 1 ECC блок приходится 51 бит информации, записанной в ADIP (из них 22 бита - физический адрес). Дополнительно во вводной зоне ADIP содержит информацию о физическом формате (256 байт, копируется в управляющую зону при инициализации):

• тип диска (+RW) и номер версии
• физический размер и максимальная скорость чтения
• плотность дорожек и длина пятна
• адреса первого и последнего блока зоны данных
• ограничения на запись
• изготовитель диска (8 байт)
• тип носителя данного изготовителя (3 байта)
• ревизия типа носителя (1 байт)
• скорость, мощность, параметры стратегии записи, рекомендации для OPC (могут быть варианты для различных скоростей)

Вводная зона состоит из

• начальной зоны (нули)
• внутренней зоны тестирования диска (используется изготовителем диска)
• внутренней зоны тестирования устройства (для OPC)
• защитной зоны 1 (разделяет тестовые зоны и полезные данные)
• резервной зоны 1 (управление плохими блоками)
• резервной зоны 2 (управление плохими блоками)
• внутренней зоны идентификации диска (набор Disk Control Block - DCB)
• резервной зоны 3 (управление плохими блоками)
• зоны опорных кодов (специальный битовый шаблон)
• буферной зоны 1 (нули)
• зоны данных управления (формат аналогичен DVD-ROM, копируется из ADIP)
• буферной зоны 2 (нули)

Выводная зона состоит из

• буферной зоны 3 (нули)
• внешней зоны идентификации диска (копия внутренней зоны)
• защитной зоны 2 (разделяет тестовые зоны и полезные данные)
• резервной зоны 4 (нули)
• внешней зоны тестирования устройства (для OPC)
• внешней зоны тестирования диска (используется изготовителем диска)
• защитной зоны 3 (нули)

Полное форматирование означает заполнение всей информационной зоны (информацией или нулями). Диск считается частично форматированным, если заполнена вводная зона, кроме начальной зоны. При этом внутрення зона идентификации диска должна содержать Formatting DCB (FDCB). Форматирование может происходить до записи на диск (необязательная проверка зоны данных), в фоновом режиме одновременно с записью, последовательная запись без форматирования (в конце записанной области создаётся временная выводная зона; может быть перезаписана при следующем сеансе записи; минимальный размер записи довольно велик).

DCB используются для обмена информацией между устройствами типа +RW. Для чтения полностью отформатированных или записанных дисков в DVD-ROM они не нужны. Обеспечиавют возможность защиты от форматирования, перезаписи и чтения управляющей информации. Каждый DCB должен содержать уникальный идентификатор последнего записавшего его устройства (изготовитель, модель, серийный номер). Пока определены 2 типа DCB

• FDCB (Formatting DCB)
  • количество изменений содержимого FDCB
  • состояние: не форматирован, частично