In computing and optical disc recording technologies, an optical disc (OD) is a flat, usually circular disc that encodes binary data (bits) in the form of pits and lands on a special material, often aluminum, on one of its flat surfaces. Its main uses are physical offline data distribution and long-term archival. Changes from pit to land or from land to pit correspond to a binary value of 1; while no change, regardless of whether in a land or a pit area, corresponds to a binary value of 0.
Universal Disk Format (UDF) is an open, vendor-neutral file system for computer data storage for a broad range of media. In practice, it has been most widely used for DVDs and newer optical disc formats, supplanting ISO 9660. Due to its design, it is very well suited to incremental updates on both recordable and (re)writable optical media. UDF was developed and maintained by the Optical Storage Technology Association (OSTA).
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.
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.
The Holographic Versatile Disc (HVD) is an optical disc technology that was expected to store up to several terabytes of data on an optical disc 10 cm or 12 cm in diameter. Its development commenced in April 2004, but it never arrived due to lack of funding. The company responsible for HVD went bankrupt in 2010.
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.
The double-density compact disc (DDCD) is an optical disc technology developed by Sony using the same laser wavelength as a compact disc, namely 780 nm. The format is defined by the Purple Book standard document. Unlike the compact-disc technology it is based on, DDCD was designed exclusively for data with no audio capabilities.
An optical jukebox is a robotic data storage device that can automatically load and unload optical discs, such as Compact Disc, DVD, Ultra Density Optical or Blu-ray and can provide terabytes (TB) or petabytes (PB) of tertiary storage. The devices are often called optical disk libraries, "optical storage archives", robotic drives, or autochangers. Jukebox devices may have up to 2,000 slots for disks, and usually have a picking device that traverses the slots and drives. Zerras Inc. provides a removeable capsule that holds up to 200 discs per library which can be scaled-out to manage 1600 discs per 42U rack unit. The arrangement of the slots and picking devices affects performance and maintenance costs, depending on the robotics design, the space between a disk and the picking device. Seek times and transfer rates vary depending upon the optical technology used.
In computing, external storage comprises devices that store information outside a computer. Such devices may be permanently attached to the computer, may be removable or may use removable media.
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.
A combo drive is a type of optical drive that combines CD-R/CD-RW recording capability with an ability to read DVD media; some manufacturers refer this as CD-RW/DVD-ROM drive. The term is used almost exclusively by Apple Inc. as a name for the low-end substitute for their high-end SuperDrive, as the latter was designed to both read and write CD and DVD recordable media. The device was created as a mid-range option between a CD burner and a DVD burner, which at the time the combo drive was introduced was generally an expensive option costing in excess of US$300 a unit.
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.
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 invented and developed in 1995 and released in late 1996. Currently allowing up to 17.08 GB of storage, the medium can store any kind of digital data and was widely used for software and other computer files as well as video programs watched using DVD players. DVDs offer higher storage capacity than compact discs while having the same dimensions. However, as with CDs, the information and data storage will begin to degrade over time with most standard DVDs lasting up to 30 years depending the type of environment they are stored and whether they are full with data.
The Blu-ray Disc (BD), often known simply as Blu-ray, is a digital optical disc storage format. It is designed to supersede the DVD format, and capable of storing several hours of high-definition video. The main application of Blu-ray is as a medium for video material such as feature films and for the physical distribution of video games for the PlayStation 3, PlayStation 4, PlayStation 5, Xbox One, and Xbox Series X. The name "Blu-ray" refers to the blue laser used to read the disc, which allows information to be stored at a greater density than is possible with the longer-wavelength red laser used for DVDs.
HD DVD is a discontinued high-density optical disc format for storing data and playback of high-definition video. Supported principally by Toshiba, HD DVD was envisioned to be the successor to the standard DVD format.
Although research into optical data storage has been ongoing for many decades, the first popular system was the Compact Disc, introduced in 1982, adapted from audio (CD-DA) to data storage with the 1985 Yellow Book, and re-adapted as the first mass market optical storage medium with CD-R and CD-RW in 1988. Compact Disc is still the de facto standard for audio recordings, although its place for other multimedia recordings and optical data storage has largely been superseded by DVD.
The preservation of optical media is essential because it is a resource in libraries, and stores audio, video, and computer data to be accessed by patrons. While optical discs are generally more reliable and durable than older media types, environmental conditions and/or poor handling can result in lost information.
The Image Mastering Application Programming Interface, or IMAPI, is a component of Microsoft Windows operating system used for CD and DVD authoring and recording.
