From http://www.webopedia.com/DidYouKnow/Hardware_Software/2003/DVDFormatsExplained.asp
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 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.
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.
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
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.
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.
Last revised Tue, 24 Jan 2006 20:01:20 -0500