DVD - Formats and Media

DVD - Digital Versatile Disc (formerly Digital Video Disc)

There are six DVD formats that are ratified by the DVD Forum;
DVD-ROM, DVD-Video, DVD-Audio, DVD-R, DVD-RW and DVD-RAM.
 

DVD-ROM

Developed as a media for distribution of computer data, there are a variety of capacities.
DVD-5 Single layer, single sided 4.7GB
DVD-10 Single layer, double sided 4.7GB per side (9.4GB)
DVD-9 Dual layer, single sided 8.5GB
DVD-17 Dual layer, double sided 8.5GB per side (17GB)

This media format is capable of being mass-produced with pre-encoded data at a pressing plant. Dual layer is now available, although it is more complex to achieve in a mass production facility.

DVD-Video

A distribution medium for films, based on DVD-5.
It can hold 133 minutes of MPEG2 video plus multiple audio channels.
The media for this format is capable of being mass-produced at a pressing plant.
After some general confusion about copyright issues, regional playing codes, and PAL/NTSC differences, DVD-video is now making an impact on the VHS tape market.

DVD-Audio

A distribution medium for Audio to the consumer based on DVD-5. It has a capacity for multi-channel sound, 24-bit sampling at 96khz bandwidth and multimedia options.
This format has recently been finalised, and consumer players are now available.
Sony is marketing a competing product called Super Audio Compact Disc (SACD) which contains a standard audio CD version as well, for backward compatibility with present CD players.

DVD-R (worm)

A write once media for computer data, split into two formats.
Authoring.
The authoring format is used for DVD-R's professional applications of prototyping and disc-checking DVD-video titles..
General.
General-use DVD-R is aimed at home video applications. These discs will be recordable in video recording devices, which will include copy protection circuits.
The discs will be read, but not write-compatible; i.e., professional recorders will write "authoring" but not "general use" discs, and vice versa.
This format lends itself to computer data archive, backup and distribution. Desktop, duplication and production devices enable software and custom applications to be delivered on DVD-R.

DVD-RAM (re-writable)

Phase Change Technology
A removable media designed for computer data storage, archive and backup. It has a higher capacity than present removable media technology and the drives and media are less expensive to manufacture than Magneto Optical products.
Media available:
Single sided 2.6GB Double sided 5.2GB
Single sided 4.7GB Double sided 9.4GB
There are now many 'fourth generation' DVD-ROM drives available that are capable of reading DVD-RAM media. The new ‘Multi’ format drives will also be able to read DVD-RAM
The cost of DVD-RAM drives and media is now very competitive.
DVD-RAM uses a different physical method of writing to the media, which provides a more robust writing process. This includes Block verify on write, Random access writing, and Block defect management.
These features and a 100,000 re-write cycle make it the best format for computer data.

DVD-RW

DVD-RW is a re-writable format, which has greater compatibility properties with DVD-R and DVD-ROM drives.
Designed as a medium for replacing VHS tape in the home, as new DVD-RW machines become increasingly available. These machines can play DVD-video discs, as well as record from the TV.

DVD-Multi drives

The DVD forum has established a set of hardware specifications to enable disc compatibility for formats officially created by the DVD forum. To this end the DVD forum has announced a hardware specification for one drive to read or write all the formats. These are:
DVD-Multi Reader Reads: DVD-video, DVD-audio, DVD-ROM, DVD-R, DVD-RW, DVD-RAM, as well as the CD formats.
DVD-Multi Writer Writes: DVD-R, DVD-RW, and DVD-RAM As well as the read capability of a DVD-Multi reader.

Other formats

There are some other formats that will soon be available in the marketplace.
4.7GB Write Once (WORM) Hitachi and JVC have announced a Write Once format, with all the benefits of DVD-RAM defect management and block verify after write.
This format has been put forward to the DVD forum for ratification as a format for the professional archive market.
PC+RW (or DVD+RW) (Sony, Philips, HP)
Capacity is 4.7GB per side.
This format will have no caddie and is an updated version of CD+RW The DVD Forum has not ratified PC+RW.
It is a competitor in the consumer market with DVD-RW.