What is DVD?

DVD -- an acronym for Digital Versatile Disc or Digital Video Disc -- is the next generation of optical storage technology. It is faster than a CD-ROM and has more storage capacity. A DVD-ROM can store up to 17GB of data on a single DVD disc. It can hold computer data, audio, as well as video. DVD is aimed at encompassing home entertainment, computers, business information and gaming into one digital format. It is expected to eventually replace audio CD, videotape, laserdisc, CD-ROM and game cartridges. DVD has widespread support from major electronics companies, major computer manufacturers, and most major movie and record studios. With this type of unprecedented support, DVD will likely succeed and become the standard for digital media in the near future. Industry sources estimate that by the year 2000, DVD ROM drive manufacturers will ship over 60 million drives per year.

There are essentially two types of DVD available today. A consumer "set top box" DVD connected to your TV. This type plays DVD video (movies) on your TV. A computer DVD, or DVD-ROM is much like your existing CD-ROM. It is hooked up to you computer and is able to read DVD data, and play interactive titles, or play DVD movies. DVD-ROM's are much more versatile then the set-top box variety.

What does a DVD look like?

A DVD-ROM disc looks just like a regular CD. Without an identifying label, you can not tell them apart.

What are the main features of the DVD?

How much data can a DVD-ROM disc hold? How is it possible?

Three advantages allow a DVD-ROM disc to store several times more data than a CD-ROM disc:

  1. The laser that reads a DVD operates at a higher frequency, which enables it to read data packed more densely on the disc. The new laser technology allows 4.7GB of data to be stored on a single side of a DVD-ROM disc.
  2. Some DVD discs have a second recording layer on top of the primary layer. This in turn doubles the storage space potentially giving a DVD-ROM disc 8.5GB of data storage.
  3. Finally, DVD can be recorded on both sides, enabling a maximum of 17GB of storage per disc.
Every DVD drive must be able to read four kinds of discs. These are; single sided single layer (4.7GB), single sided dual layer (8.5GB), double sided single layer (9.4GB), and double sided double layer (17GB).

Will I need both CD-ROM and DVD-ROM drives to allow me to use my current CD-ROM discs?

No. All DVD-ROM drives are backward compatible to CD-ROM. In other words, DVD-ROM drives can read CD-ROM discs as well as CD-Audio.

Besides the increased data storage, what else is special about DVD?

The special thing about DVD is that it was developed in conjunction with the film industry. This co-development provides a common format for pre-recorded movies and computer software. Each side of the disc can hold over 2 hours of motion video (movies) with tremendous picture quality surpassing analog laserdisc and digital satellite TV. DVD also supports multi-channel Surround Sound audio such as Dolby Laboratory's AC-3. With the added data storage capacity and availability of motion video, DVD will revolutionize interactive entertainment and educational software in the years to come.

Do I need anything other than a DVD-ROM drive to read a DVD-ROM disc?

No. All you need to read a DVD-ROM disc is a DVD drive, BUT in order to benefit from MPEG-2 video and AC-3 audio, you will require additional software or hardware. DVD movie titles are encrypted, (movie industry insisted on encryption to prevent movie piracy) therefore, you need to have special decryption mechanisms in order to watch the movies. This could come in a form of a hardware decryption chip or a software decryption algorithms.

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E-mail comments to Lon Jarvis jarvislb@jmu.edu
last updated 3/17/00