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Optical disc authoring requires a number of different optical disc recorder technologies working in tandem, from the optical disc media to the firmware to the control electronics of the optical disc drive.
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There are numerous formats of recordable optical direct to disk on the market, all of which are based on using a laser to change the reflectivity of the digital recording medium in order to duplicate the effects of the pits and lands created when a commercial optical disc is pressed. Emerging technologies such as holographic data storage and 3D optical data storage aim to use entirely different data storage methods, but these products are in development and are not yet widely available.
The earliest form is magneto-optical, which uses a magnetic field in combination with a laser to write to the medium. Though not widely used in consumer equipment, the original NeXT cube used MO media as its standard storage device, and consumer MO technology is available in the form of Sony's MiniDisc. This form of medium is rewriteable.
The most common form of recordable optical media is write-once organic dye technology, popularized in the form of the CD-R and still used for higher-capacity media such as DVD-R. This uses the laser alone to scorch a transparent organic dye (usually cyanine, phthalocyanine, or azo compound-based) to create "pits" (i.e. dark spots) over a reflective spiral groove. Most such media are designated with an R (recordable) suffix. Such discs are often quite colorful, generally coming in shades of blue or pale yellow or green.
Rewritable, non-magnetic optical media are possible using phase change alloys, which are converted between crystalline and amorphous states (with different reflectivity) using the heat from the drive laser. Such media must be played in specially tuned drives, since the phase-change material has less of a contrast in reflectivity than dye-based media; while most modern drives support such media, many older CD drives cannot recognize the narrower threshold and cannot read such discs. Phase-change discs are designated with RW (ReWriteable) or RE (Recordable-Erasable). Phase-change discs often appear dark grey.
Another technology creates pits in an inorganic carbon layer, a "write-once" option. Created by Millenniata, M-DISC, records data on special M-DISC with a data life-time of several hundred years. [1]
Optimum Power Calibration (OPC) is a function that checks the proper laser power for writing a particular session in the media in use. More sophisticated is Active OPC, which calculates the optimum laser power and adjusts it in real-time.
Optical discs can be recorded in Disc At Once, Track At Once, Session at Once (i.e. multiple burning sessions for one disc), or packet writing modes. Each mode serves different purposes:
Unlike early CD-ROM drives, optical disc recorder drives have generally used industry standard connection protocols. Early computer-based CD recorders were generally connected by way of SCSI; however, as SCSI was abandoned by its most significant users (particularly Apple Computer), it became an expensive option for most computer users. As a result, the market switched over to Parallel ATA connections for most internal drives; external drives generally use PATA drive mechanisms connected to a bridge inside the case that connects to a high-speed serial bus such as FireWire or Hi-Speed USB 2.0. Nearly all modern drives, particularly Blu-ray drives use Serial ATA.
Standalone recorders use standard A/V connections, including RCA connectors, TOSlink, and S/PDIF for audio and RF, composite video, component video, S-Video, SCART, and FireWire for video. High-bandwidth digital connections such as HDMI are unlikely to feature as recorder devices are not permitted to decrypt the encrypted video content.
Overburning is the process of recording data past the normal, vendor-specified size limit of the recordable media. Structures in the ATIP do not allow such sizes to be specified.
Overburning may be used to determine the actual capacity limit of a recordable disc, since the capacity rated by recordable disc vendors merely is the guaranteed capacity, beyond which the actual capacity is indefinite. Data located beyond the specified capacity is not guaranteed to be readable. [2]
Usually, the recorder must perform a complete write without pauses. Once the laser is on, stopping and restarting the recording process may introduce flaws.
A buffer underrun occurs during recording if the supply of data to the recorder is interrupted before the write is complete. Software typically moves the data to be recorded into a buffer; underrun occurs if the recorder processes data in the buffer faster than the software reloads it. Historically, buffer underrun was often caused by writing data obtained from a slow device, or by slowness of the recording software, from a slow processor or a processor executing other tasks concurrently.
Various recorders minimize or cope with buffer underrun in the following ways:
Buffer underrun is minimized by a strategy in which the recorder burns a packet rather than an entire session or an entire disc. When using rewritable media (CD-RW, DVD-RW, DVD-RAM), the UDF file system organizes the disc into packets that are written individually. The packets are referenced by a single, updated address table.
BURN-Proof (Buffer Underrun-Proof) is a proprietary technology for buffer underrun protection developed by Sanyo. [5]
FlextraLink is a proprietary technology for buffer underrun protection developed by Asus. [6] [7]
FlextraSpeed continuously monitors the recording media and sets the optimal writing speeds to ensure best recording quality, for discs that can’t withstand high-speed burning. [8]
Power Burn is a proprietary technology for buffer underrun protection, developed by Sony. Features:
SafeBurn is a proprietary technology for buffer underrun protection developed by Yamaha Corporation.
Packet writing is a technology that allows optical discs to be used in a similar manner to a floppy disk. Packet writing can be used both with once-writeable media and rewriteable media. Several competing and incompatible packet writing disk formats have been developed, including DirectCD and InCD. The standardized formats for packet writing are the Universal Disk Format in the plain, VAT, and spared builds.
Using the simulated writing or simulated burning feature of optical disc authoring software, the writing process will be simulated, which means that the disc spins and the laser moves as if on an actual writing process, but without any data being recorded to the disc.
This feature allows for observing the writing speeds and patterns (e.g. constant angular velocity, constant linear velocity and P-CAV and Z-CLV variants) with different writing speed settings and testing the highest capacity of an individual disc that would be achievable using overburning. [9]
This feature is standardized on CD-R, CD-RW, DVD-R and DVD-RW, but not on DVD+R and DVD+RW, on which only Plextor optical drives support simulated writing so far. [10] [11]
Retail recordable/writable optical media contain dyes in/on the optical media to record data, whereas factory-manufactured optical media use physical "pits" created by plastic molds/casts. As a result, data storage on retail optical media does not have the life-span of factory-manufactured optical media. The problem is exacerbated because as the writing laser of the recorder is used, its power output drops with age - typically after just a few years. Consequently, a disc written with a laser that is nearing the end of its useful life may not have a readable life that is as long as if a new laser had been used.
Dye based optical media should not be solely relied on to archive valuable data. MAM-A (Mitsui) claims a life of 300 years on their archival gold CD-R and 100 years for gold DVDs. Good alternatives would be to additionally backup one's media using other media technologies and/or investing in non-volatile memory technologies. [12]
CD-R is a digital optical disc storage format. A CD-R disc is a compact disc that can be written once and read arbitrarily many times.
An optical disc is a flat, usually disc-shaped object that stores information in the form of physical variations on its surface that can be read with the aid of a beam of light. Optical discs can be reflective, where the light source and detector are on the same side of the disc, or transmissive, where light shines through the disc to be detected on the other side.
In computing, an optical disc drive is a disc drive that uses laser light or electromagnetic waves within or near the visible light spectrum as part of the process of reading or writing data to or from optical discs. Some drives can only read from certain discs, but recent drives can both read and record, also called burners or writers. Compact discs, DVDs, and Blu-ray discs are common types of optical media which can be read and recorded by such drives.
A magneto-optical drive is a kind of optical disc drive capable of writing and rewriting data upon a magneto-optical disc. 130 mm (5.25 in) and 90 mm (3.5 in) discs were the most common sizes. In 1983, just a year after the introduction of the compact disc, Kees Schouhamer Immink and Joseph Braat presented the first experiments with erasable magneto-optical compact discs during the 73rd AES Convention in Eindhoven. The technology was introduced commercially in 1985. Although optical, they normally appear as hard disk drives to an operating system and can be formatted with any file system. Magneto-optical drives were common in some countries, such as Japan, but have fallen into disuse.
Optical disc authoring, including CD, DVD, and Blu-ray Disc authoring, is the process of assembling source material—video, audio or other data—into the proper logical volume format to then be recorded ("burned") onto an optical disc. This act is sometimes done illegally, by pirating copyrighted material without permission from the original artists.
DVD-RAM is a DVD-based 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.
A DVD recorder is an optical disc recorder that uses optical disc recording technologies to digitally record analog or digital signals onto blank writable DVD media. Such devices are available as either installable drives for computers or as standalone components for use in television studios or home theater systems.
In optical storage, constant linear velocity (CLV) is a qualifier for the rated speed of an optical disc drive, and may also be applied to the writing speed of recordable discs. CLV implies that the angular velocity varies during an operation, as contrasted with CAV modes. The concept of constant linear velocity was patented in 1886 by phonograph pioneers Chichester Bell and Charles Tainter.
MultiLevel Recording was a technology originally developed by Optex Corporation and promoted by Calimetrics to increase the storage capacity of optical discs. It failed to establish itself on the market. Through a combination of proprietary media, recorder, reader and player modifications, Calimetrics proposed that ML could increase the capacity of a CD-ROM, CD-R or CD-RW to 2 GB, a single-layer DVD, DVD-R, DVD+R, DVD-RW, DVD+RW or DVD-RAM to 7.1 to 10 GB and a single-layer Blu-ray Disc (BD) to as much as 60 GB. An optionally integrated Digital Rights Management (DRM) system entitled MovieGuard was also suggested. An industry group called the ML Alliance was formed in 2000 to help commercialize ML technology. Members eventually included Calimetrics, TDK, Sanyo Semiconductor, Plextor, Matsushita Kotobuki Electronics, Mitsubishi Chemical Corporation, Verbatim, Teac and Yamaha.
Phase-change Dual is a rewritable optical disc and a standard for it, developed by Matsushita Electric Industrial Co., Ltd. in April 1995.
In computing, buffer underrun or buffer underflow is a state occurring when a buffer used for communicating between two devices or processes is fed with data at a lower speed than the data is being read from it. The term is distinct from buffer overflow, a condition where a portion of memory forms a buffer of a fixed size yet is filled with more than that amount of data. This requires the program or device reading from the buffer to pause its processing while the buffer refills. This can cause undesired and sometimes serious side effects because the data being buffered is generally not suited to stop-start access of this kind.
Professional Disc (PFD) is a digital recording optical disc format introduced by Sony in 2003 primarily for XDCAM, its tapeless camcorder system. It was one of the first optical formats to utilize a blue laser, which allowed for a higher density of data to be stored on optical media compared to infrared laser technology used in the CD and red laser technology used in the DVD format.
Optical storage refers to a class of data storage systems that use light to read or write data to an underlying optical media. Although a number of optical formats have been used over time, the most common examples are optical disks like the compact disc (CD) and DVD. Reading and writing methods have also varied over time, but most modern systems as of 2023 use lasers as the light source and use it both for reading and writing to the discs. Britannica notes that it "uses low-power laser beams to record and retrieve digital (binary) data."
DVD recordable and DVD rewritable are optical disc recording technologies. Both terms describe DVD optical discs that can be written to by a DVD recorder, whereas only 'rewritable' discs are able to erase and rewrite data. Data is written ('burned') to the disc by a laser, rather than the data being 'pressed' onto the disc during manufacture, like a DVD-ROM. Pressing is used in mass production, primarily for the distribution of home video.
In optical disc authoring, there are multiple modes for recording, including Disc-At-Once, Track-At-Once, and Session-At-Once.
Drive Letter Access (DLA) is a discontinued commercial packet writing application for the Microsoft Windows operating system that allows optical disc data storage devices to be used in a manner similar to floppy disks. DLA is a packet writing technology for CD and DVD media that uses the UDF file system.
CD-RW is a digital optical disc storage format introduced in 1997. A CD-RW compact disc (CD-RWs) can be written, read, erased, and re-written.
The DVD is a digital optical disc data storage format. It was invented and developed in 1995 and first released on November 1, 1996, in Japan. The medium can store any kind of digital data and has been widely used for video programs or formerly for storing software and other computer files as well. DVDs offer significantly higher storage capacity than compact discs (CD) while having the same dimensions. A standard single-layer DVD can store up to 4.7 GB of data, a dual-layer DVD up to 8.5 GB. Variants can store up to a maximum of 17.08 GB.
As of 2021, multiple consumer-oriented, optical-disk media formats are or were available:
A CD-ROM is a type of read-only memory consisting of a pre-pressed optical compact disc that contains data. Computers can read—but not write or erase—CD-ROMs. Some CDs, called enhanced CDs, hold both computer data and audio with the latter capable of being played on a CD player, while data is only usable on a computer.