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DVD Information  | Tech Info Home Page |


DVD - Digital Video Disc ( Also known as Digital Versatile Disk )

General Information

For a listing of DVD products go to the "DVD Drives" page

DVD is a disk the same size as a CD-ROM disk.

DVD technology uses a very short wavelength laser beam to read pits from the spinning platter. The technology used will be MPEG-2 for video and AC-3 for audio. A decoding I/O card is needed to decompress the data. This card can be an ATAPI or SCSI card.

The standard DVD holds 4.7GB of information on one side of the platter.

DVD disks which are double sided ( data on both sides of the disk) must be manually flipped in order to play the other side of the disk.

There are 3 types of DVD drives, Read Only, Recordable and Rewritable.

The disks are contained in one of two types of cartridges (jackets),  Type 1 is a sealed jacket, while Type 2 allows you to remove the disk. The disk can only be written while in the jacket. The double-sided type DVD-RAM disks are Type 1.

DVD disks for PC computers are used just like CD disks, typically with NO cartridges. The DVD-RAM media is the most common one which could be used with a cartridge.

A Typical DVD disk is 120mm is size, with 8cm sizes also available to be used with camcorders and other portable devices. The 8cm disks (just like the equivalent sized CD disks) can be used on regular drives.


Standard DVD Disk

Mini DVD Disk

DVD Media Types -

DVD Read Only technology -
The Disks have a 4.7 GB capacity and the data is pressed on to the disk at production.

1) DVD-R - DVD-R (DVD-Recordable)
A recordable DVD format. Drives use the record-once writable DVD format. The drives can read pressed DVDs, and will read and record one time to DVD-R media. DVD-R is primarily used for authoring and testing of DVD titles, as well as some DVD publishing. DVD-R media is available in capacities up to 4.7GB, and is capable of being read in most read-only DVD drives and DVD-Video players.

- The recordable technology (disks) is also known as DVD-R., DVD-recordable as well as "write-once" disks.
- Write-once DVD-R discs are playback compatible with DVD-ROM and DVD-Video drives.
- The newer formats of DVD-R discs hold 4.7GB of information in contrast to the original format which had a capacity of 3.95GB.

DVD rewritable technology -
There are several incompatible formats used by rewritable DVD drives. DVD-RAM and DVD+RW (DVD Plus RW), and DVD/RW.

2) DVD-RW- D V D - RW (DVD-Re-Writable)
A rewritable version of DVD-R. It uses a phase-change recording layer, similar to CD-RW. DVD-RW media does not require a caddy or cartridge, DVD-RW media is available in capacities up to 4.7GB per side, and was designed to allow for more than 1,000 rewrites.

3) DVD-RAM - DVD-RAM (DVD-Random Access Memory)
A rewritable DVD format that allows for more than 100,000 rewrites. Media  is available as a bare disc, a single-sided disc in a removable cartridge, or a dual-sided disc in a permanent cartridge. It comes in single sided 2.6GB and double sided 5.2GB sizes. Data is written on the disk with a laser using the phase-change method. It is mostly used by Toshiba, Hitachi and Matsushita.

DVD-RAM discs are not playback-compatible with DVD-Video and DVD-ROM

4) DVD-ROM - DVD (Digital Versatile Disc)
The disc with a capacity up to 25 times greater than that CD-ROM. This Read-only format is not recordable. The term DVD-Video refers to the storage of films on DVD media.

5) DVD+RW - DVD+RW is the technology supported  by Sony and HP, uses phase-change technology to rewrite data up to 3GB per side.

6) DVD/RW (aka DVD-RW aka DVD-minus-RW ) - Typically, a rewritable DVD disk can be re-used thousands of times. Shelf life at room temperature is anywhere from 30 to 100 years. Much shorter if its run over by a chair.


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