DVD stands for digital versatile disc and in simplest terms is a high-capacity CD. In fact, every DVD-ROM drive is a CD-ROM drive; that is, they can read CDs as well as DVDs (many standalone DVD players can't read CD-R or CD-RW discs, however). DVD uses the same optical technology as CD, with the main difference being higher density.

The DVD standard dramatically increases the storage capacity of, and therefore the useful applications for, CD-ROM-sized discs. A CD-ROM can hold a maximum of about 737MB (80-minute disc) of data, which might sound like a lot but is simply not enough for many up-and-coming applications, especially where the use of video is concerned.

DVDs, on the other hand, can hold up to 4.7GB (single layer) or 8.5GB (dual layer) on a single side of the disc, which is more than 11 1/2 times greater than a CD. Double-sided DVDs can hold up to twice that amount, although you currently must manually flip the disc over to read the other side.

Up to two layers of information can be recorded to DVDs, with an initial storage capacity of 4.7GB of digital information on a single-sided, single-layer disc—a disk that is the same overall diameter and thickness of a current CD-ROM.

With Moving Picture Experts Group–standard 2 (MPEG-2) compression, that's enough to contain approximately 133 minutes of video, which is enough for a full-length, full-screen, full-motion feature film—including three channels of CD-quality audio and four channels of subtitles.

Using both layers, a single-sided disc could easily hold 240 minutes of video or more. This initial capacity is no coincidence; the creation of DVD was driven by the film industry, which has long sought a storage medium cheaper and more durable than videotape.

The initial application for DVDs was as an upgrade for CDs as well as a replacement for prerecorded videotapes. DVDs can be rented or purchased like prerecorded VCR tapes, but they offer much higher resolution and quality with greater content.

As with CDs, which initially were designed only for music, DVDs have since developed into a wider range of uses, including computer data storage and high-quality audio.

DVD History

DVD had a somewhat rocky start. During 1995, two competing standards for high-capacity CD-ROM drives were being developed to compete with each other for future market share.

One standard, called Multimedia CD, was introduced and backed by Philips and Sony, whereas a competing standard, called the Super Density (SD) disc, was introduced and backed by Toshiba, Time Warner, and several other companies.

If both standards had hit the market as is, consumers as well as entertainment and software producers would have been in a quandary over which one to choose.

Fearing a repeat of the Beta/VHS situation that occurred in the videotape market, several organizations, including the Hollywood Video Disc Advisory Group and the Computer Industry Technical Working Group, banded together to form a consortium to develop and control the DVD standard.

The consortium insisted on a single format for the industry and refused to endorse either competing proposal. With this incentive, both groups worked out an agreement on a single, new, high-capacity CD type disc in September 1995.

The new standard combined elements of both previously proposed standards and was called DVD, which originally stood for digital video disc, but has since been changed to digital versatile disc.

The single DVD standard has avoided a confusing replay of the VHS versus Beta tape fiasco for movie fans and has given the software, hardware, and movie industries a single, unified standard to support.

After agreeing on copy protection and other items, the DVD-ROM and DVD-Video standards were officially announced in late 1996. Players, drives, and discs were announced in January 1997 at the Consumer Electronics Show (CES) in Las Vegas, and the players and discs became available in March 1997.

The initial players were about $1,000 each. Only 36 movies were released in the first wave, and they were available only in seven cities nationwide (Chicago, Dallas, Los Angeles, New York, San Francisco, Seattle, and Washington, D.C.) until August 1997 when the full release began.

After a somewhat rocky start (much had to do with agreements on copy protection to get the movie companies to go along, and there was a lack of titles available in the beginning), DVD has become an incredible success. It will continue to grow as DVD moves from a read-only to a fully rewritable consumer as well as computer device.

The organization that controls the DVD video standard is called the DVD Forum and was founded by 10 companies, including Hitachi, Matsushita, Mitsubishi, Victor, Pioneer, Sony, Toshiba, Philips, Thomson, and Time Warner. Since its founding in April 1997, more than 230 companies have joined the forum.

Because it is a public forum, anybody can join and attend the meetings; the site for the DVD forum. Because the DVD Forum was unable to agree on a universal recordable format, its members who are primarily responsible for CD and DVD technology (Philips, Sony, and others) split off to form the DVD+RW Alliance in June 2000.

They have since introduced the DVD+RW format, which is the fastest, most flexible and backward-compatible recordable DVD format. DVD+RW might someday replace the VCR at home, and it's already well on its way to replacing the CD-RW and floppy drives in your PC.