DVD (Digital Versatile Disk) (page 2)
- Introduction
- DVD Formats
- DVD Configurations and Basic design
- DVD-R and DVD-RW or RAM
- DVD-ROM
- DVD-Video and DVD-Audio
- Red laser vs. Blue laser
- DVD--> VHS
- DVD-->DVD
- DVD R/RW Format Compatibility
- White Papers
DVD Formats
| Format | Application | Status | |
|---|---|---|---|
| DVD-ROM | High-capacity computer ROM storage, capable of replacing multiple CDs. Multimedia, computer games, interactive systems, databases. | Available today. | |
| DVD-Audio | High-quality surround-sound music with increased playing time. | Available today. | |
| DVD-Video | High-quality multi-lingual movies on one disk with random-access to episodes and surround-sound audio. | Available today. | |
| DVD-RAM and DVD-R | Very large (compared to CD) direct access data storage. |
Limited availability. Standards are not finally set. |
DVD Configurations and Basic design
CD Players and CD-ROM drives use an infrared laser working at a wavelength of 780 nanometers. Since the wavelength is one of the parameters responsible for the beam diameter, which translates into smaller and denser bits (click here for details), the new DVD Players and DVD-ROM drives use the red laser working at 650 nm and 635 nm wavelengths.
Another parameter, important for smaller and denser bits, is the Numerical Aperture (NA) that was achieved in DVD by refining the laser assembly.
DVD's digital modulation and ECC (error correction code) were designed to support the increased storage capacity. The 8 to 16 (EFM PLUS) modulation scheme (8 to 17 is used in a CD) is very efficient and provides backward compatibility. Also, the RS-PC (Reed Solomon Product Code) error correction code is about 10 times more robust than that currently used in CD systems.
Unlike a CD, a DVD is a bonded disc, made of two 0.6 mm substrates joined together. Although they are similar in appearance, some substantial differences between the CD and DVD are revealed under the surface.
The DVD format provides several configurations of data layers, moving from 2D storage towards 3D storage. Each configuration is designed to provide additional storage capacity:
| Name | Media structure | Capacity (GB) |
|---|---|---|
| DVD-5 | Single Side / Single Layer | 4.7 |
| DVD-9 | Single Side / Dual Layer | 8.54 |
| DVD-10 | Double Side / Single Layer | 9.4 |
| DVD-18 | Double Side / Dual Layer | 17.08 |
| DVD-R | Single or Double Side / Single Layer | 3.95 / 7.9 |
| DVD-RAM | Single or Double Side / Single Layer | 2.6 / 5.2 |
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