| When
DVD technology first appeared in households, users were simply
popping DVD discs into their DVD players to watch movies — an attractive option
to the then-conventional VCR. But just as compact disc (CD) technology
evolved so that users could record and erase and re-record data onto
compact discs, the same is now true of DVDs.
With so many different formats —
DVD+R, DVD+RW, DVD-RAM, DVD-R, DVD-RW, DVD-ROM — how do users know
which DVD format is compatible with their existing systems, and why
are there so many different formats for DVDs? The following
information sheds some light on DVD's different flavors, the
differences between them and the incompatibility issues that the
differing technologies have sprouted.
The crucial difference among the
standards is based on which standards each manufacturer
adheres to. Similar to the old VHS/Beta tape wars when VCRs first
hit the markets, different manufacturers support different
standards. Additionally, the different variations on the term DVD
(e.g. +R, -R, -ROM, and so on) describe the way data is stored on or
written to the disc itself. These are called physical formats. DVD+R and DVD+RW
DVD+R and
DVD+RW
formats are supported by Philips, Sony, Hewlett-Packard, Dell, Ricoh, Yamaha
and others.
DVD+R is a recordable DVD format similar to
CD-R. A DVD+R can record data only once and then the data becomes
permanent on the disc. The disc can not be recorded onto a second time.
DVD+RW is a re-recordable format similar to
CD-RW. The data on a DVD+RW disc can be erased and recorded over
numerous times without damaging the medium.
DVDs created by a +R/+RW device can be read
by most commercial DVD-ROM players.
|
Key Terms To
Understanding DVD Formats:
DVD
Short for digital versatile disc or digital video disc, a type of
optical disk technology similar to the CD-ROM.
DVD-Video
A video format for displaying full-length digital movies.
DVD-ROM
A type of read-only compact disc that can hold a minimum of 4.7GB
(gigabytes), enough for a full-length movie.
burn
Slang term meaning to write data to a CD-ROM or DVD-ROM.
Divx
Short for Digital video express, a new DVD-ROM format promoted by
several large Hollywood companies. With Divx, a movie (or other
data) loaded onto a DVD-ROM is playable only during a specific time
frame, typically two days. |
DVD-R, DVD-RW and DVD-RAM
These formats are supported by Panasonic, Toshiba, Apple Computer,
Hitachi, NEC, Pioneer, Samsung and Sharp. These formats are also supported
by the DVD Forum.
DVD-R is a
recordable DVD format similar to
CD-R and DVD+R. A
DVD-R can record data only once and then the data becomes permanent on the
disc. The disc cannot be recorded onto a second time. There also are two
additional standards for DVD-R disks: DVD-RG for general use, and DVD-RA for
authoring, which is used for mastering DVD video or data and is not
typically available to the general public.
DVD-RW is a re-recordable format similar to
CD-RW or DVD+RW. The data on a DVD-RW disc can be erased and recorded over
numerous times without damaging the medium. DVDs created by a -R/-RW device can be read
by most commercial DVD-ROM players.
DVD-RAM discs can
be recorded and erased repeatedly but are compatible only with devices
manufactured by the companies that support the DVD-RAM format. DVD-RAM discs
are typically housed in cartridges.
DVD+R DL and DVD-R DL
Dual layer
technology is supported by a range of manufacturers including Dell, HP,
Verbatim, Philips, Sony, Yamaha and others. As the name suggests, dual
layer technology provides two individual recordable layers on a single-sided
DVD disc. Dual Layer is more commonly called Double
Layer in the consumer market, and can be seen written as DVD+R DL or DVD-R
DL.
DVD+R DL (also called DVD+R9) is a Dual Layer
writeable DVD+R.
DVD-R DL (also called DVD-R9) is a Dual Layer writeable DVD-R. The dual
layered discs can hold 7.95GB
The dual layered discs (DVD+R9 and DVD-R9)
can hold 7.95GB and double sided dual layer (called dvd-18) can hold 15.9GB.
HD-DVD
Short for high definition-DVD, a generic term for the technology of
recording high-definition video on a DVD. In general, HD-DVD is capable of
storing between two and four times as much data as standard DVD. The two
most prominent competing technologies are Blu-ray and AOD.
Blu-ray Disc (BD)
- uses a 405nm-wavelength
blue-violet laser technology, in contrast to the 650nm-wavelength red laser
technology used in traditional
DVD formats. The
rewritable Blu-ray disc, with a
data transfer rate of 36Mbps
(1x speed) can hold up to 25GB
of
data on a single-layer disc and 50GB on a dual-layer disc. On a
50GB disc, this translates into 9 hours of high-definition (HD) video or
approximately 23 hours of standard-definition (SD) video.
The Blu-ray format was developed jointly by Sony,
Samsung, Sharp, Thomson, Hitachi, Matsushita, Pioneer and Philips,
Mistubishi and LG Electronics.
Advanced Optical Disc
(AOD) - AOD and Blu-ray are similar in that they both use 405nm-wavelength
blue-violet laser technology. while Blu-ray has a storage capacity of 25GB
on a single-layer disc, AOD has a storage capacity of 20GB on a single-layer
disc. and the capacity to hold 30GB on a dual-layer disc. AOD was developed
jointly by Toshiba and NEC.
DVD-ROM
DVD-ROM was the first DVD standard to hit the market and is a read-only
format. The video or game content is burned onto the DVD once and the DVD
will run on any DVD-ROM-equipped device. DVD-ROMs are similar to CDs.
Non-standardized DVD formats
DVD-VCD is a
DVD-Video disc that has data on it that has been encoded by using the MPEG-1
video format with the same definitions VCD has.
DVD-SVCD
is also not a valid DVD standard, since the DVD standard does not support
the SVCD resolution. The term DVD-SVCD is used to describe a hacked, or
non-standard DVD-Video disc that has SVCD compatible content on it.
DVD-MP3 is
created with and contains only digital audio files in the MP3 format. Not
all DVD players can play DVD-MP3 discs.
A Note on DVD Burners
Until 2003 consumers would have to choose a preferred DVD format and
purchase the DVD media that was compatible with the specific DVD burner. In
2003 Sony introduced a multi-format DVD burner (also called a combo drive or
DVD-Multi) and today many manufacturers offer multi-format DVD burners which
are compatible with multiple DVD formats.
|
Did You Know...
The first DVD players and discs were available in November 1996
in Japan, March 1997 in the United States, 1998 in Europe and in
1999 in Australia.
[Source] |
Last updated: November 15, 2007
DVD FAQ
A comprehensive and informative compilation of commonly asked questions (and
answers) about DVD technology.
DVD Frequently Asked
Questions (and Answers)
This is the Jul 30, 2007 revision of the official Internet DVD FAQ for the
rec.video.dvd Usenet newsgroups.
AfterDawn
AfterDawn.com was founded as a hobby project
back in spring 1999. Originally the site's focus was to provide various MP3 news
and software downloads to users and also provide a free web hosting services for
independent artists who wish to distribute their music in MP3 format for free.
DVD Overview
Outlines the technologies behind the large capacity successor to the CD, its
various formats and the compatibility issues. Includes graphics, diagrams and an
integrated glossary. This page is from "The PC Technology Guide."
Small Business Computing: Buyer's Guide: DVD Writers
These days, CD burners are standard equipment on almost every new PC. But the
immediate future lies in more powerful DVD burners that work with discs that can
hold 4.7GB of data, and may be used for performing back-ups and storing movies
that may be viewed through consumer DVD movie players.
The
DVD Forum
The DVD Forum is an international association of hardware manufacturers,
software firms, content providers and other users of Digital Versatile Discs.
USByte's
DVD Technology Page
Includes information on DVD technology including topics such as formats, lasers,
compatibility, configurations, and more.
DVD
Technical Notes
Provides a comprehensive array of technical notes about DVD technology. Sections
include: general, physical, applications, files, standard density CD, and other
Web resources.
Burn World
Everything you need to know about burning DVD
and CDs. |
