CD (Compact Disc):
An optical disc. CD is a term loosely used when describing a variety of compact disc formats, from the production (mass-produced) audio and data discs, to the write-once “recordable” versions (CD-R) or write-many "rewritable" versions (CD-RW) CDs. The standard CD can hold about 650MB of data.
CD+G (Compact Disc plus Graphics):
Primarily used for karaoke, this type of CD embeds graphical data with the audio data, allowing video pictures to be displayed periodically
as music is played. A special player is needed to read and display
CD-I (Compact Disc-Interactive):
A compact disc format designed to allow interactive multimedia applications
(digital audio and video, video games, and software applications)
to be run on a player attached to a television.
CD-R (Compact Disc-Recordable):
A version of CD on which data can be recorded but not erased. An organic dye-based material is used to hold data that are written to it by a laser.
CD-ROM (Compact Disc-Read Only Memory):
An extension of the compact disc digital audio format that allows computer data to be stored.
A peripheral device attached to a computer that allows it to read and play all CDs.
CD-RW (Compact Disc-ReWritable):
A version of CD on which data can be recorded and erased and re-recorded in the same physical location of the disc. A phase-changing metal alloy film is used to hold the data that are written to it by the laser.
Once stood for Digital Video Disc or Digital Versatile Disc, now just DVD. The next generation of optical disc storage technology after the CD. A DVD is the same physical size and shape as a CD, but has a higher density and gives the option for data to be double-sided or double-layered in the disc.
An audio-only storage format similar to CD-Audio. DVD-Audio differs, however, in offering 16, 20 and 24-bit samples at a variety of sampling rates from 44.1 to 192KHz, compared with 16 bits and 44.1KHz for CDs. The latest audio format more than doubles the fidelity of a standard CD. DVD-Audio discs can also contain music videos, graphics, and other information.
DVD-R (DVD-Recordable, sometimes referred to as DVD minus R):
A version of DVD on which data can be recorded, but not erased, by a disc drive. An organic, dye-based material is used to hold data that are written to it by a laser. DVD-R provides secure recording for volumes of information that cannot be accidentally or intentionally altered. DVD-R has a capacity of 4.7 GB. There are two versions of DVD-R:
1. DVD-R (A) (DVD-Recordable for Authoring):
A format for professional content developers and software producers.
Primarily used to create master discs that will be mass-produced by software houses and multimedia/video postproduction facilities.
2. DVD-R (G) (DVD-Recordable for General use) and DVD+R (DVD plus Recordable):
A format for general recording of all types of content: audio, video, and data. Compatible with most DVD-Video players and DVD-ROM drives.
The differences between DVD-R and DVD+R are as follows:
—DVD+R uses a different technique from DVD-R in how the laser follows the disc track while writing data to the disc. A writer disc-drive is generally capable of writing to one type of disc but some may be capable of writing to both types. All DVD drives should read both DVD-R and DVD+R.
—DVD-R uses constant linear velocity (CLV) for the disc rotation; DVD+R can use CLV or constant angular velocity (CAV) for the disc rotation. CAV allows for easier random access of data on the disc.
—DVD+R can provide lossless linking of new data added from multiple
DVD-RAM (DVD-Random Access Memory):
A rewritable DVD. It is a cartridge-based, or, more recently, cartridge-
less optical disc for data recording and playback. Data can be recorded and erased up to 100,000 times, making the DVD-RAM a virtual hard disk. DVD RAM uses a phase-change data layer to record data written to it by a laser. Current DVD-ROM drives and DVD-Video players cannot read DVD-RAM media.
DVD-ROM (Read Only Memory):
Typically, an optical disc used for storing data, interactive sequences, audio, and video. DVD-ROMs run in DVD-ROM, DVD-R, DVD-RW, or DVD-RAM drives, but not in DVD-Video players connected to televisions and home theaters. However, most DVD-ROM drives will play DVD-Video movies if the associated software is installed in the computer.
DVD-RW (sometimes referred to as DVD minus RW, DVD-ReWritable):
The DVD-RW is similar to DVD-RAM except that its technology features
a sequential read-write access more like a phonograph than a hard disk. Its read-write capacity is 4.7 GB, and it can be re-written to about 1,000 times. For general recording of all types of content, for audio, for video recording and editing, and for random data recording.
Compatible with most DVD-Video players and DVD-ROM drives.
DVD+RW (DVD plus RW), (DVD-ReWritable):
For general recording of all types of content, for audio, for video recording and editing, and for random data recording. Compatible with most DVD-Video players and DVD-ROM drives.
Care and Handling of CDs and DVDs—A Guide for Librarians and Archivists 33
The differences between DVD-RW and DVD+RW are as follows:
—DVD+RW uses a different technique from DVD-RW in how the laser follows the disc track while writing data to the disc. A writer disc-drive is generally capable of writing to one type of disc but some may be capable of writing to both types. Most newer DVD drives should read both DVD-RW and DVD+RW.
—DVD-RW uses constant linear velocity (CLV) for the disc rotation; DVD+RW can use CLV or constant angular velocity (CAV) for the disc rotation. CAV allows for easier random access of data on the disc.
—DVD+RW can provide lossless linking of new data inserted or added from multiple recording sessions.
Used for viewing movies and for other visual entertainment, DVD Video is a popular format for high-quality MPEG2 or MPEG4 video and digital surround sound. It enables multilanguage, multisubtitling,
and other advanced user features. The total capacity is 17 GB if two layers are used on both sides of the disk.