The Technology pages provide an introduction to the CD and DVD formats plus provisional information on the new higher density versions to be launched in 2005.
· The Compact Disc was launched in 1982 for high quality digital audio and has become one of the most successful examples of consumer electronics technology.
· In 1984 the CD Audio specification was extended to CD-ROM for computer applications and was subsequently extended to other formats all based on the audio compact disc format.
· In 1996 DVD became available in Japan and was then launched in the USA in 1997 and Europe in 1998. DVD is available in three formats: DVD-Video for high quality movies, DVD-ROM for games and other computer applications and DVD-Audio for high quality music. There is also the DualDisc, launched at the end of 2004.
· In 2005, two new formats will be launched offering movies in high definition video.
Deluxe offers our customers a full range of CD and DVD services including premastering, replication and fulfilment.
Click on the links on the left or the logos on the right to find out more about these technologies and the various CD & DVD formats and how they are manufactured. There is also a glossary of terms relevant to CD, DVD and the applications they are used for
DVD technology
DVD technology was developed to provide an optical disc format with a much larger capacity than the CD, for a wide range of applications. Pre-recorded DVD discs provide capacities from 4.7 GB to 17.1 GB and can support a wide range of applications, including DVD-Video and DVD-Audio.
The term DVD-ROM is used to define both the physical/logical format of pre-recorded DVD discs and the computer multimedia applications of DVD. DVD-ROM discs, as opposed to DVD-Video or DVD-Audio discs, are being used for games, encyclopaedias and other applications where the large size is needed. In addition DVD-Video and DVD-Audio discs often include a DVD-ROM section with data that runs on a PC, giving additional features such as Internet access
The Disc
As a disc, DVD looks very much like the CD. Both are shiny discs that are 4 3/4 inches (12.0 cm) in diameter. Both are optical formats containing digital information. This means a laser pickup is used to read the digital data encoded on the disc. But that's where the similarities end.
DVD is actually a family of physical and application formats. As far as the physical format, DVD can hold anywhere from seven times to over 25 times the digital data on a CD, depending on the the disc's construction. Additionally, the DVD may be used for video, audio, or data storage applications as a DVD-Video, DVD-Audio, or DVD-ROM application format, respectively.
The Physical Format
There are three reasons for DVD's greater data capacity:
1. Smaller pit size
2. Tighter track spacing
3. Multiple layer capability
Smaller Pit Size. DVDs have smaller pit size than CDs. Pits are the slight depressions or dimples on the surface of the disc that allow the laser pickup to distinguish between the digital 1's and 0's.
Tighter Track Spacing. DVDs also feature tighter track spacing (i.e., track pitch) between the spirals of pits. In order for a DVD player to read the smaller pit size and tighter track spacing of the DVD format, a different type of laser with a smaller beam of light is required. (This is one of the major reasons why CD players cannot read DVDs, while DVD players are capable of reading Audio CDs.)
A comparison of a CD's pit size and track spacing vs. that of a DVD
Multiple Layer Capability. Finally, DVDs may have up to 4 layers of information, with two layers on each side. To read information on the second layer (on the same side), the laser focuses deeper into the DVD and reads the pits on the second layer. When the laser switches from one layer to another layer, it is referred to as the "layer switch" or the "RSDL (reverse spiral dual layer) switch". To read information from the other side of the DVD, almost all DVD players require the user to manually flip the disc.
Based on DVD's dual-layer and double-sided options, there are four disc construction formats:
1. Single-sided, single-layered
2. Single-sided, dual-layered
3. Double-sided, single-layered
4. Double-sided, dual-layered
Single-Sided, Single-Layered. Also known as DVD-5, this simplest construction format holds 4.7 Gigabytes (GBytes) of digital data. The "5" in "DVD-5" signifies the nearly 5 GBytes worth of data capacity. Compared to 650 Megabytes (MB) of data on CD, the basic DVD-5 has over seven times the data capacity of that of a CD. That's enough digital information for approximately two hours of digital video and audio for DVD-Video, or 74 minutes of high resolution music for DVD-Audio.
Single-Sided, Dual-Layered. The DVD-9 construction holds about 8.5 GBytes. DVD-9s do not require manual flipping: the DVD player automatically switches to the second layer in a fraction of a second, by re-focusing the laser pickup on the deeper second layer. This capability allows for uninterrupted playback of long movies up to four hours! Frequently, DVD-9 is used to put a movie and its rich set of bonus materials on the same DVD-Video disc, or its optional DTS Surround Sound track.
Double-Sided, Single-Layered. Known as DVD-10, this construction features a capacity of 9.4 GBytes of data. DVD-10s are commonly used to put a widescreen version of the movie on one side, and a full frame version of the same movie on the other side. Almost all DVD players require you to manually flip the DVD, that's why the DVD-10 is called the "flipper" disc. (There are a few DVD players that can perform the side flipping automatically.)
Double-Sided, Dual-Layered. The DVD-18 construction can hold approximately 17 GBytes (almost 26 times the data capacity of a CD), or about 8 hours of video and audio as a DVD-Video. Think of DVD-18 as a double-sided DVD-9, where up to four hours of uninterrupted video and audio can be stored on one side. To access the content on the other side of a DVD-18, you have to manually flip the DVD. To date, few titles have been released using this construction. Content providers (e.g., movie studios) usually choose to go with two DVD-9s than a single DVD-18 because DVD-18s cost far more to produce
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