writable DVD: A GUIDE FOR THE PERPLEXED

Emedia Professional,  Jan, 1999  by Dana J. Parker

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Standards and Standards-Bearers

Q: How many rewritable DVD formats are there?

A: There are three rewritable high-density optical formats that use the DVD name. They are DVD-RAM, DVD-RW, and DVD+RW. There is one recordable DVD format, DVD-R(ecordable).

For the sake of brevity (and also in accordance with precedent set by OSTA), the recordable/rewritable formats can be lumped under one descriptor--writable DVD.

Q: Isn't DVD-RAM the only official, standard format?

A: DVD-RAM is one of two rewritable DVD formats endorsed by the DVD Forum. The other is DVD-RW. DVD-R is the record-once format endorsed by the DVD Forum. However, although the DVD Forum creates the specifications for DVD and licenses the logo, and they are not an official standards-setting body.

DVD+RW is the rewritable format backed by two original Forum members--Philips and Sony--as well as Hewlett-Packard, Mitsubishi Chemical, Yamaha, and Ricoh, collectively known as the DVD+RW Compatibility Alliance (DCA).

None of the writable formats using the DVD name and logo is any more "standard" than any other. All four of the writable DVD specifications have been submitted to and accepted by the European Computer Manufacturers Association (ECMA) and are being considered by the International Organization for Standardization (ISO).

Q: Why can't these companies agree to make just one format?

A: The DVD Forum's members spent over a year trying to agree on a single rewritable format. Unfortunately, while technological superiority and backwards compatibility were small factors in their design, political and economic considerations were far more important. Each of several companies wanted their own patented technology to be included in the specification for rewritable DVD, and each one wanted the others' technology to be excluded or minimized. Ultimately, the design for DVD-RAM included many technology patents owned by Toshiba, Hitachi, and Matsushita, some of which are currently used in PD (phase-change dual) and MO; and excluded much of the technology patents from Philips and Sony, some of which are currently used in CD-R and CD-RW. Sony, Philips and Hewlett-Packard, along with Yamaha and Ricoh, decided to use these patented technologies, and others to make a rewritable DVD technology. Meanwhile, Pioneer developed a rewritable version of their DVD-R technology called DVD-R/W, which was eventually accepted by the DVD Forum under the name DVD-RW.

While it may appear as if the best course would be to settle on one rewritable DVD technology for all markets and applications, there is considerable support for the view that a single universal standard for high-density removable optical storage is neither necessary or desirable. There are distinct differences between the proposed formats, and, in the end, these differences may make one of them more suitable to a given application than another.

Q. Who manufactures/supports these different formats?

A: DVD-RAM is endorsed by the DVD Forum, and is manufactured by Hitachi, Toshiba, and Matsushita (Panasonic). DVD-R is endorsed by the DVD Forum, and is manufactured by Pioneer. Sony has shown an "experimental" DVD-R drive. DVD-RW is endorsed by the DVD Forum and prototypes have been manufactured by Pioneer, Yamaha, and Ricoh. DVD+RW is endorsed by the members of the Yokohama Group, also called DCA; Sony, Ricoh, Philips, Yamaha, Hewlett-Packard, and Mitsubishi Chemical; drives can be reasonably expected from Hewlett-Packard, Philips, Sony, and other electronics manufacturers, although no official product announcements have been made to date.