Optical disc recorder - AbsoluteAstronomy.com

Computing

Computing is usually defined as the activity of using and improving computer hardware and software. It is the computer-specific part of information technology...

, an optical disc drive (ODD) is a disk drive that uses laser

Laser

A laser is a device that emits light through a process of optical amplification based on the stimulated emission of photons. The term "laser" originated as an acronym for Light Amplification by Stimulated Emission of Radiation...

light or electromagnetic waves near the light spectrum as part of the process of reading or writing data to or from optical disc

Optical disc

In computing and optical disc recording technologies, an optical disc is a flat, usually circular disc which encodes binary data in the form of pits and lands on a special material on one of its flat surfaces...

s. Some drives can only read from discs, but recent drives are commonly both readers and recorders, also called burners or writers. Compact disc

Compact Disc

The Compact Disc is an optical disc used to store digital data. It was originally developed to store and playback sound recordings exclusively, but later expanded to encompass data storage , write-once audio and data storage , rewritable media , Video Compact Discs , Super Video Compact Discs ,...

s, DVD

DVD

A DVD is an optical disc storage media format, invented and developed by Philips, Sony, Toshiba, and Panasonic in 1995. DVDs offer higher storage capacity than Compact Discs while having the same dimensions....

s, and Blu-ray disc

Blu-ray Disc

Blu-ray Disc is an optical disc storage medium designed to supersede the DVD format. The plastic disc is 120 mm in diameter and 1.2 mm thick, the same size as DVDs and CDs. Blu-ray Discs contain 25 GB per layer, with dual layer discs being the norm for feature-length video discs...

s are common types of optical media which can be read and recorded by such drives. Optical drive is the generic name; drives are usually described as "CD" "DVD", or "Blu-Ray", followed by "drive", "writer", etc.

Optical disc drives are an integral part of stand-alone consumer appliances such as CD players, DVD player

DVD player

A DVD player is a device that plays discs produced under both the DVD-Video and DVD-Audio technical standards, two different and incompatible standards. These devices were invented in 1997 and continue to thrive...

s and DVD recorder

DVD recorder

A DVD recorder , is an optical disc recorder that uses Optical disc recording technologies to digitally record analog signal or digital signals onto blank writable DVD media...

s. They are also very commonly used in computers to read software and consumer media distributed on disc, and to record discs for archival and data exchange purposes. Floppy disk drives, with capacity of 1.44 MB, have been made obsolete: optical media are cheap and have vastly higher capacity to handle the large files used since the days of floppy discs, and the vast majority of computers and much consumer entertainment hardware have optical writers. USB flash drive

USB flash drive

A flash drive is a data storage device that consists of flash memory with an integrated Universal Serial Bus interface. flash drives are typically removable and rewritable, and physically much smaller than a floppy disk. Most weigh less than 30 g...

s, high-capacity, small, and inexpensive, are suitable where read/write capability is required.

Disc recording is restricted to storing files playable on consumer appliances (film

Film

A film, also called a movie or motion picture, is a series of still or moving images. It is produced by recording photographic images with cameras, or by creating images using animation techniques or visual effects...

s, music, etc.), relatively small volumes of data (e.g., a standard DVD holds 4.7 gigabyte

Gigabyte

The gigabyte is a multiple of the unit byte for digital information storage. The prefix giga means 109 in the International System of Units , therefore 1 gigabyte is...

s) for local use, and data for distribution, but only on a small-scale; mass-producing large numbers of identical discs is cheaper and faster than individual recording.

Optical discs are used to back up

Backup

In information technology, a backup or the process of backing up is making copies of data which may be used to restore the original after a data loss event. The verb form is back up in two words, whereas the noun is backup....

relatively small volumes of data, but backing up of entire hard drives, typically containing many hundreds of gigabytes, is less practical than with the smaller capacities available previously. Large backups are often made on external hard drives, as their price has dropped to a level making this viable; in professional environments magnetic tape drives

Tape drive

A tape drive is a data storage device that reads and performs digital recording, writes data on a magnetic tape. Magnetic tape data storage is typically used for offline, archival data storage. Tape media generally has a favorable unit cost and long archival stability.A tape drive provides...

are also used.

History

The first laser disk, demonstrated in 1972, was the Laservision 12-inch video disk. The video signal was stored as an analog format like a video cassette. The first digitally recorded optical disc was a 5-inch audio compact disc (CD) in a read-only format created by Philips and Sony in 1975. Five years later, the same two companies introduced a digital storage solution for computers using this same CD size called a CD-ROM. Not until 1987 did Sony demonstrate the erasable and rewritable 5.25-inch optical drive.

Laser and optics

The most important part of an optical disc drive is an optical path, placed in a pickup head (PUH), usually consisting of semiconductor laser

Laser

, a lens

Lens (optics)

A lens is an optical device with perfect or approximate axial symmetry which transmits and refracts light, converging or diverging the beam. A simple lens consists of a single optical element...

for guiding the laser beam, and photodiode

Photodiode

A photodiode is a type of photodetector capable of converting light into either current or voltage, depending upon the mode of operation.The common, traditional solar cell used to generateelectric solar power is a large area photodiode....

s detecting the light reflection from disc's surface.

Initially, CD lasers with a wavelength

Wavelength

In physics, the wavelength of a sinusoidal wave is the spatial period of the wave—the distance over which the wave's shape repeats.It is usually determined by considering the distance between consecutive corresponding points of the same phase, such as crests, troughs, or zero crossings, and is a...

of 780 nm were used, being within infrared range. For DVDs, the wavelength was reduced to 650 nm (red color), and the wavelength for Blu-ray Disc was reduced to 405 nm (violet color).

Two main servomechanism

Servomechanism

thumb|right|200px|Industrial servomotorThe grey/green cylinder is the [[Brush |brush-type]] [[DC motor]]. The black section at the bottom contains the [[Epicyclic gearing|planetary]] [[Reduction drive|reduction gear]], and the black object on top of the motor is the optical [[rotary encoder]] for...

s are used, the first one to maintain a correct distance between lens and disc, and ensure the laser beam is focused on a small laser spot on the disc. The second servo moves a head along the disc's radius, keeping the beam on a groove, a continuous spiral data path.

On read only media (ROM), during the manufacturing process the groove, made of pits, is pressed on a flat surface, called land. Because the depth of the pits is approximately one-quarter to one-sixth of the laser's wavelength, the reflected beam's phase is shifted in relation to the incoming reading beam, causing mutual destructive interference and reducing the reflected beam's intensity. This is detected by photodiodes that output electrical signals.

A recorder encodes (or burns) data onto a recordable CD-R

CD-R

A CD-R is a variation of the Compact Disc invented by Philips and Sony. CD-R is a Write Once Read Many optical medium, though the whole disk does not have to be entirely written in the same session....

, DVD-R

DVD-R

DVD-R is a DVD recordable format. A DVD-R typically has a storage capacity of 4.71 GB. Pioneer has also developed an 8.5 GB dual layer version, DVD-R DL, which appeared on the market in 2005....

, DVD+R

DVD+R

DVD+R is part of optical disc recording technologies. It is a format for optical disc data storage that utilizes digital recording. It is similar to, but incompatible with, the older DVD-R standard...

, or BD-R disc (called a blank) by selectively heating parts of an organic dye

Dye

A dye is a colored substance that has an affinity to the substrate to which it is being applied. The dye is generally applied in an aqueous solution, and requires a mordant to improve the fastness of the dye on the fiber....

layer with a laser. This changes the reflectivity of the dye, thereby creating marks that can be read like the pits and lands on pressed discs. For recordable discs, the process is permanent and the media can be written to only once. While the reading laser is usually not stronger than 5 mW

Watt

The watt is a derived unit of power in the International System of Units , named after the Scottish engineer James Watt . The unit, defined as one joule per second, measures the rate of energy conversion.-Definition:...

, the writing laser is considerably more powerful. The higher writing speed, the less time a laser has to heat a point on the media, thus its power has to increase proportionally. DVD burners' lasers often peak at about 200 mW, either in continuous wave and pulses, although some have been driven up to 400 mW before the diode fails.

For rewritable CD-RW

CD-RW

A CD-RW is a rewritable optical disc. It was introduced in 1997, and was known as "CD-Writable" during development. It was preceded by the CD-MO, which was never commercially released....

, DVD-RW

DVD-RW

A DVD-RW disc is a rewritable optical disc with equal storage capacity to a DVD-R, typically 4.7 GB. The format was developed by Pioneer in November 1999 and has been approved by the DVD Forum. The smaller Mini DVD-RW holds 1.46 GB, with a diameter of 8 cm.The primary advantage of DVD-RW over...

, DVD+RW

DVD+RW

DVD+RW is a physical format for rewritable DVDs and can hold up to 4.7 GB. DVD+RW was created by the DVD+RW Alliance, an industry consortium of drive and disc manufacturers...

, DVD-RAM

DVD-RAM

DVD-RAM is a disc specification presented in 1996 by the DVD Forum, which specifies rewritable DVD-RAM media and the appropriate DVD writers. DVD-RAM media have been used in computers as well as camcorders and personal video recorders since 1998.-Design:DVD-RAM is one of three competing...

, or BD-RE media, the laser is used to melt a crystal

Crystal

A crystal or crystalline solid is a solid material whose constituent atoms, molecules, or ions are arranged in an orderly repeating pattern extending in all three spatial dimensions. The scientific study of crystals and crystal formation is known as crystallography...

line metal alloy

Alloy

An alloy is a mixture or metallic solid solution composed of two or more elements. Complete solid solution alloys give single solid phase microstructure, while partial solutions give two or more phases that may or may not be homogeneous in distribution, depending on thermal history...

in the recording layer of the disc. Depending on the amount of power applied, the substance may be allowed to melt back (change the phase back) into crystalline form or left in an amorphous

Amorphous solid

In condensed matter physics, an amorphous or non-crystalline solid is a solid that lacks the long-range order characteristic of a crystal....

form, enabling marks of varying reflectivity to be created.

Double-sided media may be used, but they are not easily accessed with a standard drive, as they must be physically turned over to access the data on the other side.

Double layer (DL) media have two independent data layers separated by a semi-reflective layer. Both layers are accessible from the same side, but require the optics to change the laser's focus. Traditional single layer (SL) writable media are produced with a spiral groove molded in the protective polycarbonate

Polycarbonate

PolycarbonatePhysical PropertiesDensity 1.20–1.22 g/cm3Abbe number 34.0Refractive index 1.584–1.586FlammabilityV0-V2Limiting oxygen index25–27%Water absorption – Equilibrium0.16–0.35%Water absorption – over 24 hours0.1%...

layer (not in the data recording layer), to lead and synchronize the speed of recording head. Double-layered writable media have: a first polycarbonate layer with a (shallow) groove, a first data layer, a semi-reflective layer, a second (spacer) polycarbonate layer with another (deep) groove, and a second data layer. The first groove spiral usually starts on the inner edge and extends outwards, while the second groove starts on the outer edge and extends inwards.

Some drives support Hewlett-Packard

Hewlett-Packard

Hewlett-Packard Company or HP is an American multinational information technology corporation headquartered in Palo Alto, California, USA that provides products, technologies, softwares, solutions and services to consumers, small- and medium-sized businesses and large enterprises, including...

's LightScribe

LightScribe

LightScribe is an optical disc recording technology that uses specially coated recordable CD and DVD media to produce laser-etched labels with text or graphics, as opposed to stick-on labels and printable discs....

photothermal printing technology for labeling specially coated discs.

Rotational mechanism

Optical drives' rotational mechanism differs considerably from hard disk drives', in that the latter keep a constant angular velocity

Constant angular velocity

In optical storage, constant angular velocity is a qualifier for the rated speed of an optical disc drive, and may also be applied to the writing speed of recordable discs...

(CAV), in other words a constant number of revolutions per minute

Revolutions per minute

Revolutions per minute is a measure of the frequency of a rotation. It annotates the number of full rotations completed in one minute around a fixed axis...

(RPM). With CAV, a higher throughput

Throughput

In communication networks, such as Ethernet or packet radio, throughput or network throughput is the average rate of successful message delivery over a communication channel. This data may be delivered over a physical or logical link, or pass through a certain network node...

is generally achievable at an outer disc area, as compared to inner area.

On the other hand, optical drives were developed with an assumption of achieving a constant throughput, in CD drives initially equal to 150 KiB/s. It was a feature important for streaming audio

Sound

Sound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations.-Propagation of...

data that always tend to require a constant bit rate

Bit rate

In telecommunications and computing, bit rate is the number of bits that are conveyed or processed per unit of time....

. But to ensure no disc capacity is wasted, a head had to transfer data at a maximum linear rate at all times too, without slowing on the outer rim of disc. This had led to optical drives—until recently—operating with a constant linear velocity

Constant linear velocity

In optical storage, constant linear velocity is a qualifier for the rated speed of an optical disc drive, and may also be applied to the writing speed of recordable discs. CLV implies that the angular velocity varies during an operation, as contrasted with CAV modes...

(CLV). The spiral groove of the disc passed under its head at a constant speed. Of course the implication of CLV, as opposed to CAV, is that disc angular velocity is no longer constant, and spindle motor need to be designed to vary speed between 200 RPM on the outer rim and 500 RPM on the inner rim.

Later CD drives kept the CLV paradigm, but evolved to achieve higher rotational speeds, popularly described in multiples of a base speed. As a result, a 4× drive, for instance, would rotate at 800-2000 RPM, while transferring data steadily at 600 KiB/s, which is equal to 4 × 150 KiB/s.

For DVD base speed, or "1× speed", is 1.385 MB/s, equal to 1.32 MiB/s, approximately 9 times faster than the CD base speed. For Blu-ray drives base speed is 6.74 MB/s, equal to 6.43 MiB/s.

There are mechanical limits to how quickly a disc can be spun. Beyond a certain rate of rotation, around 10000 RPM, centrifugal stress can cause the disc plastic to creep

Creep (deformation)

In materials science, creep is the tendency of a solid material to slowly move or deform permanently under the influence of stresses. It occurs as a result of long term exposure to high levels of stress that are below the yield strength of the material....

and possibly shatter

CD shattering

CD shattering, DVD shattering and optical disc shattering , a phenomenon also known as exploding CDs, occurs when a optical disc shatters inside a high speed optical disc drive with a loud cracking sound. Typically, the disc and the drive will be ruined...

. On the outer edge of the CD, 10000 RPM limitation roughly equals to 52× speed, but on the inner edge only to 20×. Some drives further lower their maximum read speed to around 40× on the reasoning that blank discs will be clear of structural damage, but that discs inserted for reading may not be. Without higher rotational speeds, increased read performance may be attainable by simultaneously reading more than one point of a data groove, but drives with such mechanisms are more expensive, less compatible, and very uncommon.

Because keeping a constant transfer rate for the whole disc is not so important in most contemporary CD uses, to keep the rotational speed of the disc safely low while maximizing data rate, a pure CLV approach needed to be abandoned. Some drives work in partial CLV (PCLV) scheme, by switching from CLV to CAV only when a rotational limit is reached. But switching to CAV requires considerable changes in hardware design, so instead most drives use the zoned constant linear velocity (Z-CLV) scheme. This divides the disc into several zones, each having its own different constant linear velocity. A Z-CLV recorder rated at "52×", for example, would write at 52× on the innermost zone and then progressively decrease the speed in several discrete steps down to 20× at the outer rim.

Loading mechanisms

Current optical drives use either a tray-loading mechanism, where the disc is loaded onto a motorised or manually operated tray, or a slot-loading mechanism, where the disc is slid into a slot and drawn in by motorized rollers. Slot-loading drives have the disadvantage that they cannot usually accept the smaller 80 mm discs or any non-standard sizes; however, the Wii

Wii

The Wii is a home video game console released by Nintendo on November 19, 2006. As a seventh-generation console, the Wii primarily competes with Microsoft's Xbox 360 and Sony's PlayStation 3. Nintendo states that its console targets a broader demographic than that of the two others...

and PlayStation 3

PlayStation 3

The is the third home video game console produced by Sony Computer Entertainment and the successor to the PlayStation 2 as part of the PlayStation series. The PlayStation 3 competes with Microsoft's Xbox 360 and Nintendo's Wii as part of the seventh generation of video game consoles...

video game consoles seem to have defeated this problem, for they are able to load standard size DVDs and 80 mm discs in the same slot-loading drive.

A small number of drive models, mostly compact portable units, have a top-loading mechanism where the drive lid is opened upwards and the disc is placed directly onto the spindle (for example, all PlayStation 1 consoles, portable CD players, and some standalone CD recorders all feature top-loading drives).

These sometimes have the advantage of using spring-loaded ball bearings to hold the disc in place, minimizing damage to the disc if the drive is moved while it is spun up.

Some early CD-ROM drives used a mechanism where CDs had to be inserted into special cartridges or caddies

Caddy (hardware)

In computer hardware, a caddy refers to a sheath used to hold some media.If the medium is a hard disk drive, the caddy is also referred to as a disk enclosure, which is discussed there...

, somewhat similar in appearance to a 3.5" floppy diskette. This was intended to protect the disc from accidental damage by enclosing it in a tougher plastic casing, but did not gain wide acceptance due to the additional cost and compatibility concerns—such drives would also inconveniently require "bare" discs to be manually inserted into an openable caddy before use.

Computer interfaces

Most internal drives for personal computer

Personal computer

A personal computer is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end-user with no intervening computer operator...

s, server

Server (computing)

In the context of client-server architecture, a server is a computer program running to serve the requests of other programs, the "clients". Thus, the "server" performs some computational task on behalf of "clients"...

s and workstation

Workstation

A workstation is a high-end microcomputer designed for technical or scientific applications. Intended primarily to be used by one person at a time, they are commonly connected to a local area network and run multi-user operating systems...

s are designed to fit in a standard 5.25" drive bay

Drive bay

A drive bay is a standard-sized area for adding hardware to a computer. Most drive bays are fixed to the inside of a case, but some can be removed....

and connect to their host via an ATA or SATA

Sata

Sata is a traditional dish from the Malaysian state of Terengganu, consisting of spiced fish meat wrapped in banana leaves and cooked on a grill.It is a type of Malaysian fish cake, or otak-otak...

interface. Additionally, there may be digital and analog outputs for Red Book audio. The outputs may be connected via a header cable to the sound card or the motherboard. At one time, computer software resembling cd players controlled playback of the CD. Today the information is extracted from the disc as data, to be played back or converted to other file formats.

External drives usually have USB or FireWire interfaces. Some portable versions for laptop use power themselves off batteries or off their interface bus.

Drives with SCSI

SCSI

Small Computer System Interface is a set of standards for physically connecting and transferring data between computers and peripheral devices. The SCSI standards define commands, protocols, and electrical and optical interfaces. SCSI is most commonly used for hard disks and tape drives, but it...

interface were made, but they are less common and tend to be more expensive, because of the cost of their interface chipsets, more complex SCSI connectors, and small volume of sales.

When the optical disc drive was first developed, it was not easy to add to computer systems. Some computers such as the IBM PS/2 were standardizing on the 3.5" floppy and 3.5" hard disk, and did not include a place for a large internal device. Also IBM PCs and clones at first only included a single ATA

ATA

ATA or Ata may refer to:* Ata , people with the first name or family name-Education:* Ashcroft Technology Academy, Wandsworth, London, England* Advanced Technologies Academy, a high school in Las Vegas, Nevada, USA...

drive interface, which by the time the CDROM was introduced, was already being used to support two hard drives. Early laptops simply had no built-in high-speed interface for supporting an external storage device.

This was solved through several techniques:

Early sound cards could include a second ATA interface, though it was often limited to supporting a single optical drive and no hard drives. This evolved into the modern second ATA interface included as standard equipment
A parallel port
Parallel port
A parallel port is a type of interface found on computers for connecting various peripherals. In computing, a parallel port is a parallel communication physical interface. It is also known as a printer port or Centronics port...

external drive was developed that connected between a printer and the computer. This was slow but an option for laptops
A PCMCIA optical drive interface was also developed for laptops
A SCSI card could be installed in desktop PCs for an external SCSI drive enclosure, though SCSI was typically much more expensive than other options

Compatibility

Most optical drives are backwards compatible with their ancestors up to CD, although this is not required by standards.

Compared to a CD's 1.2 mm layer of polycarbonate, a DVD's laser beam only has to penetrate 0.6 mm in order to reach the recording surface. This allows a DVD drive to focus the beam on a smaller spot size and to read smaller pits. DVD lens supports a different focus for CD or DVD media with same laser.

	Pressed CD	CD-R CD-R A CD-R is a variation of the Compact Disc invented by Philips and Sony. CD-R is a Write Once Read Many optical medium, though the whole disk does not have to be entirely written in the same session....	CD-RW CD-RW A CD-RW is a rewritable optical disc. It was introduced in 1997, and was known as "CD-Writable" during development. It was preceded by the CD-MO, which was never commercially released....	Pressed DVD	DVD-R DVD-R DVD-R is a DVD recordable format. A DVD-R typically has a storage capacity of 4.71 GB. Pioneer has also developed an 8.5 GB dual layer version, DVD-R DL, which appeared on the market in 2005....	DVD+R DVD+R DVD+R is part of optical disc recording technologies. It is a format for optical disc data storage that utilizes digital recording. It is similar to, but incompatible with, the older DVD-R standard...	DVD-RW DVD-RW A DVD-RW disc is a rewritable optical disc with equal storage capacity to a DVD-R, typically 4.7 GB. The format was developed by Pioneer in November 1999 and has been approved by the DVD Forum. The smaller Mini DVD-RW holds 1.46 GB, with a diameter of 8 cm.The primary advantage of DVD-RW over...	DVD+RW DVD+RW DVD+RW is a physical format for rewritable DVDs and can hold up to 4.7 GB. DVD+RW was created by the DVD+RW Alliance, an industry consortium of drive and disc manufacturers...	DVD+R DL DVD+R DL DVD+R DL also called DVD+R9, is a derivative of the DVD+R format created by the DVD+RW Alliance. Its use was first demonstrated in October 2003. DVD+R DL discs employ two recordable dye layers, each capable of storing nearly the 4.7 GB capacity of a single-layer disc, almost doubling the total...	Pressed CAT BD	BD-R	BD-RE	BD-R DL	BD-RE DL
Audio CD player	Read	Read	Read	None	None	None	None	None	None	None	None	None	None	None
CD-ROM CD-ROM A CD-ROM is a pre-pressed compact disc that contains data accessible to, but not writable by, a computer for data storage and music playback. The 1985 “Yellow Book” standard developed by Sony and Philips adapted the format to hold any form of binary data.... drive	Read	Read	Read	None	None	None	None	None	None	None	None	None	None	None
CD-R CD-R A CD-R is a variation of the Compact Disc invented by Philips and Sony. CD-R is a Write Once Read Many optical medium, though the whole disk does not have to be entirely written in the same session.... recorder	Read	Write	Read	None	None	None	None	None	None	None	None	None	None	None
CD-RW CD-RW A CD-RW is a rewritable optical disc. It was introduced in 1997, and was known as "CD-Writable" during development. It was preceded by the CD-MO, which was never commercially released.... recorder	Read	Write	Write	None	None	None	None	None	None	None	None	None	None	None
DVD-ROM drive	Read	Read	Read	Read	Read	Read	Read	Read	Read	None	None	None	None	None
DVD-R DVD-R DVD-R is a DVD recordable format. A DVD-R typically has a storage capacity of 4.71 GB. Pioneer has also developed an 8.5 GB dual layer version, DVD-R DL, which appeared on the market in 2005.... recorder	Read	Write	Write	Read	Write	Read	Read	Read	Read	None	None	None	None	None
DVD-RW DVD-RW A DVD-RW disc is a rewritable optical disc with equal storage capacity to a DVD-R, typically 4.7 GB. The format was developed by Pioneer in November 1999 and has been approved by the DVD Forum. The smaller Mini DVD-RW holds 1.46 GB, with a diameter of 8 cm.The primary advantage of DVD-RW over... recorder	Read	Write	Write	Read	Write	Read	Write	Read	Read	None	None	None	None	None
DVD+R DVD+R DVD+R is part of optical disc recording technologies. It is a format for optical disc data storage that utilizes digital recording. It is similar to, but incompatible with, the older DVD-R standard... recorder	Read	Write	Write	Read	Read	Write	Read	Read	Read	None	None	None	None	None
DVD+RW DVD+RW DVD+RW is a physical format for rewritable DVDs and can hold up to 4.7 GB. DVD+RW was created by the DVD+RW Alliance, an industry consortium of drive and disc manufacturers... recorder	Read	Write	Write	Read	Read	Write	Read	Write	Read	None	None	None	None	None
DVD±RW recorder	Read	Write	Write	Read	Write	Write	Write	Write	Read	None	None	None	None	None
DVD±RW/DVD+R DL recorder	Read	Write	Write	Read	Write	Write	Write	Write	Write	None	None	None	None	None
BD-ROM	Read	Read	Read	Read	Read	Read	Read	Read	Read	Read	Read	Read	Read	Read
BD-R recorder	Read	Write	Write	Read	Write	Write	Write	Write	Write	Read	Write	Read	Read	Read
BD-RE recorder	Read	Write	Write	Read	Write	Write	Write	Write	Write	Read	Write	Write	Read	Read
BD-R DL recorder	Read	Write	Write	Read	Write	Write	Write	Write	Write	Read	Write	Read	Write	Read
BD-RE DL recorder	Read	Write	Write	Read	Write	Write	Write	Write	Write	Read	Write	Write	Write	Write

Some types of CD-R media with less-reflective dyes may cause problems. May not work in non MultiRead-compliant drives. May not work in some early-model DVD-ROM drives. A large-scale compatibility test conducted by cdrinfo.com in July 2003 found DVD-R discs playable by 96.74%, DVD+R by 87.32%, DVD-RW by 87.68% and DVD+RW by 86.96% of consumer DVD players and DVD-ROM drives. Read compatibility with existing DVD drives may vary greatly with the brand of DVD+R DL media used. Need information on read compatibility. May not work in non DVD Multi-compliant drives. Recorder firmware may blacklist or otherwise refuse to record to some brands of DVD-RW media. Need information on read compatibility. As of April 2005, all DVD+R DL recorders on the market are Super Multi

Super Multi

Super Multi is a term used to label DVD recorders that support both "minus" and "plus" DVD formats, as well as DVD-RAM....

-capable. As of October 2006, recently released BD drives are able to read and write CD media.

Recording performance

Optical recorder drives are often marked with three different speed ratings. In these cases, the first speed is for write-once (R) operations, second for re-write (RW or RE) operations, and one for read-only (ROM) operations. For example a 12/10/32× CD drive is capable of writing to CD-R discs at 12× speed (1.76 MB/s), write to CD-RW discs at 10× speed (1.46 MB/s), and read from any CDs at 32× speed (4.69 MB/s).

In the late 1990s, buffer underruns

Buffer underrun

In computing, buffer underrun or buffer underflow is a state occurring when a buffer used to communicate between two devices or processes is fed with data at a lower speed than the data is being read from it. This requires the program or device reading from the buffer to pause its processing while...

became a very common problem as high-speed CD recorders began to appear in home and office computers, which—for a variety of reasons—often could not muster the I/O performance to keep the data stream to the recorder steadily fed. The recorder, should it run short, would be forced to halt the recording process, leaving a truncated track that usually renders the disc useless.

In response, manufacturers of CD recorders began shipping drives with "buffer underrun protection" (under various trade names, such as Sanyo

Sanyo

is a major electronics company and member of the Fortune 500 whose headquarters is located in Moriguchi, Osaka prefecture, Japan. Sanyo targets the middle of the market and has over 230 Subsidiaries and Affiliates....

's "BURN-Proof", Ricoh

Ricoh

or Ricoh, is a Japanese company that was established in 1936 on February 6th, as , a company in the RIKEN zaibatsu. Its headquarters is located in Ricoh Building in Chūō, Tokyo....

's "JustLink" and Yamaha's "Lossless Link"). These can suspend and resume the recording process in such a way that the gap the stoppage produces can be dealt with by the error-correcting

Reed–Solomon error correction

In coding theory, Reed–Solomon codes are non-binary cyclic error-correcting codes invented by Irving S. Reed and Gustave Solomon. They described a systematic way of building codes that could detect and correct multiple random symbol errors...

logic built into CD players and CD-ROM drives. The first of these drives were rated at 12× and 16×.

Recording schemes

CD recording on personal computers was originally a batch-oriented task in that it required specialised authoring software to create an "image" of the data to record, and to record it to disc in the one session. This was acceptable for archival purposes, but limited the general convenience of CD-R and CD-RW discs as a removable storage medium

Removable media

In computer storage, removable media refers to storage media which is designed to be removed from the computer without powering the computer off.Some types of removable media are designed to be read by removable readers and drives...

.

Packet writing

Packet writing

Packet writing or IPW , is an optical disc recording technology used to allow write-once and rewritable CD and DVD media to be used in a similar manner to a floppy disk from within the operating system, i.e., it allows users to create, modify, and delete files and directories on demand without the...

is a scheme in which the recorder writes incrementally to disc in short bursts, or packets. Sequential packet writing fills the disc with packets from bottom up. To make it readable in CD-ROM and DVD-ROM drives, the disc can be closed at any time by writing a final table-of-contents to the start of the disc; thereafter, the disc cannot be packet-written any further. Packet writing, together with support from the operating system

Operating system

An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...

and a file system

File system

A file system is a means to organize data expected to be retained after a program terminates by providing procedures to store, retrieve and update data, as well as manage the available space on the device which contain it. A file system organizes data in an efficient manner and is tuned to the...

like UDF, can be used to mimic random write-access as in media like flash memory and magnetic disks.

Fixed-length packet writing (on CD-RW and DVD-RW media) divides up the disc into padded, fixed-size packets. The padding reduces the capacity of the disc, but allows the recorder to start and stop recording on an individual packet without affecting its neighbours. These resemble the block-writable access offered by magnetic media closely enough that many conventional file systems will work as-is. Such discs, however, are not readable in most CD-ROM and DVD-ROM drives or on most operating systems without additional third-party drivers.

The DVD+RW disc format goes further by embedding more accurate timing hints in the data groove of the disc and allowing individual data blocks to be replaced without affecting backwards compatibility (a feature dubbed "lossless linking"). The format itself was designed to deal with discontinuous recording because it was expected to be widely used in digital video recorder

Digital video recorder

A digital video recorder , sometimes referred to by the merchandising term personal video recorder , is a consumer electronics device or application software that records video in a digital format to a disk drive, USB flash drive, SD memory card or other local or networked mass storage device...

s. Many such DVRs use variable-rate video compression schemes which require them to record in short bursts; some allow simultaneous playback and recording by alternating quickly between recording to the tail of the disc whilst reading from elsewhere.

Mount Rainier

Mount Rainier (packet writing)

Mount Rainier is a format for writable optical discs which provides the packet writing and defect management. Its goal is the replacement of the floppy disk...

aims to make packet-written CD-RW and DVD+RW discs as convenient to use as that of removable magnetic media by having the firmware format new discs in the background and manage media defects (by automatically mapping parts of the disc which have been worn out by erase cycles to reserve space elsewhere on the disc). As of February 2007, support for Mount Rainier is natively supported in Windows Vista

Windows Vista

Windows Vista is an operating system released in several variations developed by Microsoft for use on personal computers, including home and business desktops, laptops, tablet PCs, and media center PCs...

. All previous versions of Windows require a third-party solution, as does Mac OS X

Mac OS X

Mac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems...

Recorder Unique Identifier

Owing to pressure from the music industry, as represented by the IFPI and RIAA

Recording Industry Association of America

The Recording Industry Association of America is a trade organization that represents the recording industry distributors in the United States...

, Philips

Philips

Koninklijke Philips Electronics N.V. , more commonly known as Philips, is a multinational Dutch electronics company....

developed the Recorder Identification Code (RID) to allow media to be uniquely associated with the recorder that has written it. This standard is contained in the Rainbow Books

Rainbow Books

The Rainbow Books are a collection of standards defining the formats of Compact Discs.Red BookYellow BookThe Rainbow Books are a collection of standards defining the formats of Compact Discs.Red Book...

. The RID-Code consists of a supplier code (e.g. "PHI" for Philips), a model number and the unique ID of the recorder. Quoting Philips, the RID "enables a trace for each disc back to the exact machine on which it was made using coded information in the recording itself. The use of the RID code is mandatory."

Although the RID was introduced for music and video industry purposes, the RID is included on every disc written by every drive, including data and backup discs.

Source IDentification Code

The Source IDentification Code (SID) is an eight character supplier code that is placed on every CD-ROM. The SID identifies not only manufacturer, the individual factory, and even the machine that produced the (blank, writeable) disc.

Quoting Philips: "The Source IDentification Code (SID Code) provides an optical disc production facility with the means to identify:

all discs mastered and/or replicated in its plant;
and the individual Laser Beam Recorder (LBR) signal processor or mould that produced a particular stamper or disc."

Use of RID and SID together in forensics

The standard use of RID and SID mean that each disc written contains a record of the machine that produced a disc (the SID), and which drive wrote it (the RID). This combined knowledge may be very useful to law enforcement, to investigative agencies, and to private and/or corporate investigators.

External links

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