Guide to Cataloging DVDs
Using AACR2r Chapters 7 and 9

Created by the DVD Cataloging Task Force
Cataloging Policy Committee
Online Audiovisual Catalogers, Inc.

Jump to: Table of Contents | Introduction | DVD Videos | DVD-ROMs | Resources

I. Introduction

by Robert Freeborn

This section provides a general overview of DVD technology. Topics covered include a brief history, a comparison of DVDs with compact disc (CD) technology, the different types of DVD that are currently available, and a glimpse at the future of DVDs.

History

DVDs were first developed in 1995 through a consortium of ten companies: Hitachi, JVC, Matsushita, Mitsubishi, Philips, Pioneer, Sony, Thomson, Time Warner, and Toshiba. These companies formed the DVD Consortium, which in April 1997 became the DVD Forum. The mission of the forum is to promote the worldwide acceptance of DVD products across the entertainment, consumer electronics and IT industries. In early 2000, membership in the DVD Forum reached some 230 companies and organizations that are engaged in DVD research, development and/or manufacturing. Although DVD once stood for “Digital Video Disc” or “Digital Versatile Disc,” DVD now simply stands for DVD.

DVD vs CD

Both DVDs and CDs consist of 12 cm (4 ¾ in.) diameter discs containing billions of tiny pits (non-reflective holes) and lands (reflective bumps) arranged in one long spiral track. These pits and lands represent the zeros and ones of digital information, and are read by a laser. The main differences are that a DVD’s pits and lands are shorter and narrower than those of a CD, and that the DVD’s laser also has a shorter wavelength. In terms of storage, this means that a DVD can hold 4.7 billion bytes of information; seven times the informational capacity of a standard CD. DVDs can also hold two information layers on one side which roughly increase their storage to 9 gigabytes. Unlike CDs, DVDs can also hold information on both sides of a single disc.

DVD types

DVD-A (DVD-Audio) — Equivalent to an standard audio CD which uses Pulse Code Modulation (PCM) for recording sound, except that it holds some seven times the information of a regular CD.

DVD-V (DVD-Video) — What most people think of when referring to the DVD. Usually used to store video recordings.

DVD-R (DVD-Recordable) — A write-once data storage disc that is similar to CD-Rs. It can record around 4.7 gigabytes, and is used mainly for the archiving of information and the storage of video recordings.

DVD-RAM (DVD-Re-writable) — An erasable, re-recordable version of the DVD-ROM. Provides random access to its 4.7 gigabytes of recorded information, and is best suited for use in computers. May be rewritten some 100,000 times.

DVD-ROM — Equivalent to the CD-ROM, a commercially produced read-only disc containing computer programs, data or both. Can hold anywhere between 4.7 and 17 gigabytes of information.

DVD-RW (DVD-Re-writable) — A re-writable version of the DVD-R that is compatible with most DVD video players. It can sequentially record almost 4.7 gigabytes of data, and can be rewritten about 1,000 times.

DVD+RW (DVD-Re-writable) — Competing standard to DVD-RAM and DVD-RW developed by Sony, Philips and Hewlett-Packard. It also sequentially records almost 4.7 gigabytes of data and can be rewritten some 1,000 times. DVD-RAMs, DVD-RWs, and DVD+RWs are incompatible with each other.

SACD (Super Audio CD) — Competing audio standard to DVD-A that utilizes Direct Stream Digital (DSD) recording technology instead of PCM.

Future

The DVD Forum is working on something they call “DVD Multi.” DVD Multi is a set of hardware specifications designed to enable disc compatibility for virtually all formats officially created by the DVD Forum. For example, a DVD Multi-compliant DVD-ROM computer drive would be able to read all of the following: DVD-V, DVD-A, DVD-ROM, DVD-RAM, DVD-RW, and DVD-R discs.

In February 2002, 9 members of the DVD Forum announced a new high-density recordable DVD standard known as Blu-Ray (it uses a blue laser to read and store the information rather than the typical red laser). The Forum is investigating many possible next-generation DVD standards, but Blu-Ray is considered to be the most likely successor because of its support by these 9 current members. While originally intended for storing video, Blu-Ray will probably be adapted for use in computer information storage and retrieval.