digital versatile disc

digital versatile disc

digital versatile disc or digital video disc (DVD), a small plastic disc used for the storage of digital data. The successor media to the compact disc (CD), a DVD can have as much as 26 times the storage capacity of a CD. When compared to CD technology, DVD also allows for better graphics and greater resolution. In the case of an audio recording, where the data to be stored is in analog rather than digital form, the sound signal is sampled at a rate of 48,000 or 96,000 times a second, then each sample is measured and digitally encoded on the 43/4-in. (12-cm) disc as a series of microscopic pits on an otherwise polished surface. The disc is covered with a protective, transparent coating so that it can be read by a laser beam. As with other optical disks nothing touches the encoded portion, and the DVD is not worn out by the playing process. Because DVD players are backward compatible to existing technologies, they can play CD and CD-ROM discs; however, CD players cannot play DVD and DVD-ROM discs.

DVD formats include DVD-Video (often simply called DVD), DVD-ROM, and DVD-Audio. DVD-Video discs hold digitized movies or video programs and are played using a DVD player hooked up to a standard television receiver. In a sense, DVD-Video players are the successors to the videocasette recorders (VCRs) that play VHS tapes. DVD-ROM [Read Only Memory] discs hold computer data and are read by a DVD-ROM drive hooked up to a computer. These disks can only be read—the disks are impressed with data at the factory but once written cannot be erased and rewritten with new data. DVD-ROM also includes recordable variations. DVD-R [Recordable] discs can be written to sequentially but only once. DVD-RAM [Random Access Memory], DVD-RW, and DVD+RW [ReWritable] discs can be written to thousands of times; they differ in their technical standards and, as a result, in the amount of information they can hold. Many DVD recorders can record in several different recordable DVD formats. Some recorders include computer hard drives that allow the user to record tens to hundreds of hours of material temporarily; the user can then select the material that will be transferred to a DVD. When DVD was released in 1996 there was no DVD-Audio format, although the audio capabilities of DVD-Video far surpassed those available from a CD; the DVD-Audio format was introduced in 1999.

The Enhanced Versatile Disc (EVD) is an optical medium-based digital audio/video format, developed to provide a means for playing HDTV content using existing optical media. It was announced on November 18 2003 by China's Xinhua News Agency as a response to the popular DVD-Video format and its licensing costs (which some considered excessive). It uses an optical storage medium in CD size (120 mm) that is physically a DVD disc with the same UDF file system. China started development on EVD in 1999, because DVD Video (CSS, Macrovision, etc.) and MPEG-2 (Video and Systems) licensing costs were relatively high — reportedly in the range of $13–$20 USD per hardware video player.

On the EVD, the video codecs VP5 and VP6 from On2 Technologies were supposed to be used. These are more efficient than MPEG-2 Video and could enable the disc to store HDTV resolutions, which the standard DVD format does not support. With EVD, royalties to On2 for the VP6 codec part of the EVD design were anticipated to be about $2 USD per video player (a much lower fee than that associated with MPEG-2 Video). However, a contract dispute rapidly developed between On2 and Beijing E-World (the consortium of companies developing the EVD format). On2 announced in April 2004 that it was not being properly paid and would file multiple breach of contract claims against E-World for arbitration. Approximately one year later, the arbitrator dismissed all of On2's claims and ruled that nothing was owed to On2, primarily because no significant number of player devices had ever been produced by the E-World companies. While the EVD format design including VP6 had been proposed to the Chinese government to become a standard, the effort appears to have stalled at that point and no further progress is evident.

The audio codec was to come from Coding Technologies and was called the EAC (Enhanced Audio Codec) 2.0. It is the successor of a prior design known as EAC and works on the basis of spectral band replication. EAC 2.0 supports mono, stereo and 5.1 surround sound.

The development was supported by the Chinese government and was developed by Beijing E-world Technology (a multi-company partnership including SVA, Shinco, Xiaxin, Yuxing, Skyworth, Nintaus, Malata, Changhong, and BBK), which reported the overcoming of development, chip-design and production problems. The team applied for 25 patents, of which at least seven have currently been granted.

Prototype EVD discs and software players were presented in April 2004. As the disc is physically a DVD disc it could be read with any computer DVD drive. Successful copies were made with DVD-R discs. The number of films ever offered in the format was very limited.

Following the contract dispute in spring 2004, very little news was available about EVD until December 6th, 2006, when 20 Chinese electronic firms unveiled 54 prototype EVD players, announcing their intention to fully switch to this format by 2008 in an effort to decrease dependency on foreign electronic products and establish a niche in the market. Although earlier attempts have been made, none have had such widespread support as this.

It is speculated that currently no EVD is currently encoding in an HDTV resolution or an Image Constraint Token is preventing all discs to be displayed at full resolution. Support for the disc format had been dropped by the Xinhua Bookstore in Wuhan, which was a major supporter of the format, due to a lack of sales. The official Chinese EVD site (www.evd.cn) has also gone offline.

List of EVDs Released

See also

External links

Search another word or see digital versatile discon Dictionary | Thesaurus |Spanish
Copyright © 2014 Dictionary.com, LLC. All rights reserved.
  • Please Login or Sign Up to use the Recent Searches feature
FAVORITES
RECENT

;