The current state of recordable DVD media formats - Tape/Disk/Optical Storage

Computer Technology Review, March, 2002 by Tim Clatterbuck

CD-R and -RW continue to be the most widely used removable storage technology because of the extremely low cost of drives, players, and media. However, with prices for DVD hardware and media dropping, the DVD recordable formats are rapidly gaining acceptance for use in document, video, audio, and personal/professional storage.

The prime selling points of DVD are its inherent reliability and massive data storage capabilities--ultimately up to 9.4GB of removable storage with a double-sided disc.

According to Wolfgang Schlichting, IDC's Research Manager, Removable Storage, 2002 will be the year when many consumers will discover the benefits of DVD recording. IDC projects that worldwide DVD media sales will climb from 50 million discs in 2002 to nearly 150 million in 2004.

There are basically two markets for recordable DVD: computer storage and A/V recording. While all of the format developers have focused on providing a single format that will work for both video and computer applications, each DVD format has its strengths and weaknesses

Applications

All DVD media formats share common parameters for use in a wide range of personal and professional applications. The discs look very similar; however, they do not all work in every DVD drive, DVD-Video player, or DVD recorder.

While the DVD formats have important technical differences, Tables 1 and 2 have been developed to help content developers and users determine which media is best for them.

General Format Discussion

DVD-R, a recordable version of DVD-ROM--The DVD Forum has developed specifications for two write-once DVD-R categories--Authoring and General use. Although both types of DVD-R media can be read by nearly all DVD drives and players, technical differences make it impossible to write to DVD-R Authoring media using a consumer DVD-R General system and vice versa. DVD-R General recorders use a 650 nm recording laser wavelength while DVD-R Authoring uses a 635 nm laser. In addition, the General Use media contains content protection technology to prevent users from making bit-for-bit copies of CSS- encrypted entertainment titles (Table 3).

DVD-R for Authoring was designed to meet the needs of professional content developers and software producers. The media is primarily used to create master discs that will be mass produced by software houses, multimedia/video post-production facilities, and archiving.

DVD-R for General Use was developed for business and consumer applications--data archiving and one-time video recording. Delivering 2X write performance, which is equivalent to an 18x CD write speed, the media provides secure recording for volumes of information that cannot be accidentally or intentionally altered. The low storage cost, 100-year data life, and broad compatibility also make DVD-R General media ideal for small-scale distribution of DVD content. DVD-R general discs can be played back by the vast majority of the DVD-ROM drives and video players in use today. Available with street prices as low as $5, the media can be used by DVD-R General drives from Pioneer, Apple, Compaq, Sony, Panasonic, and other leading manufacturers.

DVD R--The write-once DVD R specification is an extension of the DVD RW format supported by the DVD RW alliance: HP, Philips, Ricoh, Sony, Yamaha, Verbatim/ Mitsubishi Chemical, Dell, and Thomson. Similar in functionality and compatibility to DVD-R General, DVD R was designed to provide widespread playback on DVD-ROM drives and DVD video players. DVD R/ RW drives write at 2.4x speed, recording a full DVD disc about 5 minutes faster than 2x writers. DVD R drives and media provide a reliable, low-cost storage solution for archiving home videos, photos, mixed media presentations, and data that require protection from alteration or erasure. Low-cost DVD R media will be used withDVD R/ RW drives and video recorders announced by HP, Dell, Philips, Ricoh, and Sony.

DVD-RW--DVD-RW is officially referred to as a "re-recordable" format by the DVD Forum, but is commonly known as a rewriteable format. Available with a capacity of 4.7GB, DVD-RW media is recorded sequentially, making it ideal for streaming video applications. DVD-RW media contains protection technology that prevents copying of copy-righted content. Users can write to the disc in multiple sessions as long as the disc has not been finalized, but DVD drives and players can only read DVD-RW media after the disc has been finalized. Currently offering 1x write performance, DVD-RW discs can be overwritten 1,000 times. Most legacy DVD-ROM drives and DVD players, especially those produced in the past two years, will read DVD-RW media. Available at street pricing approaching $10, DVD-RW discs are used by drives and video recorders from Pioneer, Compaq, Sony, and other manufacturers.

DVD RW--Introduced in October 2001, DVD RW is a rewriteable format developed by the DVD RW Alliance.Offering 2.4x recording and 1,000 rewrites, the 4.7GB DVD RW technology is used by consumers for both audio/video and data storage applications. DVD RW incorporates lossless linking technology, allowing the drive or video recorder to accurately stop and start the writing process, or to replace individual 32kB data blocks. Lossless linking improves compatibility, performance, and ease of use, and permits support of drag-and-drop applications like the Mount Ranier specification (similar to CD-RW functionality). For PC applications, DVD RW hardware can optionally support CAV (constant angular velocity) recording to enable fast, random-access reading of the disc. With multi-session writing technology, users who have not finalized the disc can quickly add documents, data, and video segments without having to open and close write sessions. By incorporating the RW specification for defect management, manufacturers ensure that data is accurately written to and read from the disc. DVD RW media, which is currently available for $10 to $15, is compatible with RW drives and video recorders from HP, Philips, Sony, Dell Computer, and other leading manufacturers.