Production Glossary
DVD
The DVD was created by four different companies (Panasonic, Sony, Toshiba, and Philips) in 1995. The origin of the acronym DVD comes from the phrase “digital versatile disc”, but is more unofficially referred to as a “digital videodisk”.DVDs provide the capacity to store up to 17.08 GB of storage (thanks to double-layer recording technology), compared to the CD which can only store up to 650 megabytes of data. The DVD is regularly glitch free and able to be viewed more often than a video cassette tape, which can wear out with constant viewing. The DVD provides a superior format with the ability to skip forward or backwards without the need of fast-forward and rewind and makes storage and transport of entertainment and other data easier due to its compact size.
The DVD comes in multiple forms that offer different functions for the consumer. The most common form of a DVD is the DVD-ROM, a disc that is unable to be erased and recorded on. Movies and box set TV shows are an example of the DVD-ROM. Because of its interactivity and the great quality of picture and sound, the DVD was chosen as the successor to the video cassette tape.
DVDs are also able to record and store media. These DVDs are known as recordable or re-writable discs (DVD-R/RW, DVD-RAM, DVD+R/RW). Generally used for storing a backup copy of data and transportation, the re-writable DVDs enable the user to store more data in one location than previous forms of secondary storage.
A DVD that is manufactured with data already recorded on it goes through a stamping process in which the information is physically stamped onto the DVD. This data is embedded into the DVD using a circling trail of pits and lands that begins at the center and then snakes around and around until it lands on the outermost edge. When the disc is double-layered, that trail of pits continues on a second layer of the DVD or, in the case of a double-sided DVDs, on to the opposite side of the disc. In order to be read by the DVD player, a beam of laser tracks the spinning disc enabling a mechanism specific to the player to identify the intensity of the beam’s reflection in the pits and lands. The variance in the reflections are then translated into bits of info that form bytes.
The DVD has seen two successors, the HD DVD and Blu-ray Disc. While both of these options provide increased storage (30 GB and 50 GB respectively), it does not appear that they will eradicate the use of the standard DVD format. In fact, DVDs are still the dominating format culminating in 87% of video sales per year and contributing to the near 1 billion DVD player sales per year.
