DVD, Digital Versatile Disc, is the next generation of optical disc storage technology. It's a bigger, faster CD that can hold video as well as audio and computer data. DVD aims to encompass home entertainment, computers, and business information with a single digital format, eventually replacing audio CD, videotape, laserdisc, CD-ROM, and perhaps even video game cartridges. DVD has widespread support from all major electronics companies, all major computer hardware companies, and most major movie and music studios, which is unprecedented and says much for its chances of success.

It's important to understand the difference between DVD-Video and DVD-ROM. DVD-Video (often simply called DVD) holds video programs and is played in a DVD player hooked up to a TV. DVD-ROM holds computer data and is read by a DVD-ROM drive hooked up to a computer. The difference is similar to that between Audio CD and CD-ROM. DVD-ROM also includes future variations that are recordable one time (DVD-R) or many times (DVD-RAM). Most people expect DVD-ROM to be initially much more successful than DVD-Video. Most new computers with DVD-ROM drives will also be able to play DVD-Videos.

There's also a DVD-Audio format. The technical specifications for DVD-Audio are not yet determined.

• Over 2 hours of high-quality digital video (over 8 on a double-sided, dual-layer disc).
• Support for widescreen movies on standard or widescreen TVs (4:3 and 16:9 aspect ratios).
• Up to 8 tracks of digital audio (for multiple languages), each with as many as 8 channels.
• Up to 32 subtitle/karaoke tracks.
• Automatic "seamless" branching of video (for multiple story lines or ratings on one disc).
• Up to 9 camera angles (different viewpoints can be selected during playback).
• Menus and simple interactive features (for games, quizzes, etc.).
• Multilingual identifying text for title name, album name, song name, cast, crew, etc.
• "Instant" rewind and fast forward, including search to title, chapter, track, and timecode.
• Durability (no wear from playing, only from physical damage).
• Not susceptible to magnetic fields. Resistant to heat.
• Compact size (easy to handle and store, players can be portable, replication is cheaper).

Note: Most discs do not contain all features (multiple audio/subtitle tracks, seamless branching, parental control, etc.). Some discs may not allow searching or skipping on programming.

Most players support a standard set of features:

• Language choice (for automatic selection of video scenes, audio tracks, subtitle tracks, and menus).*
• Special effects playback: freeze, step, slow, fast, and scan (no reverse play or reverse step).
• Parental lock (for denying playback of discs or scenes with objectionable material).*
• Programmability (playback of selected sections in a desired sequence).
• Random play and repeat play.
• Digital audio output (PCM stereo and Dolby®Digital).
• Compatibility with audio CDs.

* Must be supported by additional content on the disc.

Some players include additional features:

• Component (YPRPB or RGB) output for highest-quality picture.
• Compatibility with Video CDs.
• Six-channel analog output from internal audio decoder.
• Compatiblity with laserdiscs and CDVs.
• Reverse single frame stepping.
• RF output (for TVs with no direct video input).
• Multilingual on-screen display.

DVD has the capability to produce near-studio-quality video and better-than-CD-quality audio. DVD is vastly superior to videotape and generally better than laserdisc. However, quality depends on many production factors. Until compression experience and technology improves we will occasionally see DVDs that are inferior to laserdiscs.

DVD video is compressed from digital studio master tapes to MPEG-2 format. This is a "lossy" compression which removes redundant information (such as sections of the picture that don't change) and information that's not readily perceptible by the human eye. The resulting video, especially when it is complex or changing quickly, may sometimes contain "artifacts" such as blockiness, fuzziness, and video noise depending on the processing quality and amount of compression. At average rates of 3.5 Mbps (million bits/second), artifacts may be occasionally noticeable. Higher data rates result in higher quality, with almost no perceptible difference from the original master at rates above 6 Mbps. As MPEG compression technology improves, better quality is being achieved at lower rates.

DVD audio quality is excellent. One of DVD's audio formats is LPCM (linear pulse code modulation) with sampling sizes and rates higher than audio CD. Alternately, audio for most movies is stored as discrete multi-channel surround sound using Dolby Digital or MPEG-2 audio compression similar to the surround sound formats used in theaters. As with video, audio quality depends on how well the encoding was done. Most audio on DVD will be in Dolby Digital format, which is close to CD quality.

Mass-market DVD movie players currently list for $150 and up. Be warned, DVD players under $400 are basically throw-aways if anything major should fail. The average in-warranty repairs we have performed had parts costs (wholesale) in the $250 range!

DVD-ROM drives for computers sell for around $200 to $500. Prices are expected to drop quickly to current CD-ROM drive levels.

It varies, but most discs list for $25 to $30 with street prices between $19 and $25, even those with supplemental material. Some new releases are initially priced for rental (near $80, the same as VHS); others are as low as $15.

DVD-ROMs will initially be slightly more expensive than CD-ROMs since there is more on them, they cost more to replicate, and the market is smaller. But once production costs drop and the installed base of drives grow, DVD-ROMs will cost about the same as CD-ROMs today.

Motion picture studios want to control the home release of movies in different countries because theater releases aren't simultaneous (a movie may come out on video in the U.S. when it's just hitting screens in Europe). Also, studios sell distribution rights to different foreign distributors and would like to guarantee an exclusive market. Therefore they have required that the DVD standard include codes which can be used to prevent playback of certain discs in certain geographical regions. Each player is given a code for the region in which it's sold. The player will refuse to play discs which are not allowed in that region. This means that discs bought in one country may not play on players bought in another country.

Regional codes are entirely optional. Discs without codes will play on any player in any country. It's not an encryption system, it's just one byte of information on the disc that the player checks. Some studios have already announced that only their new releases will have regional codes, but so far almost all releases play in only one region.

An audio standard expected to appear first at the end of 1997.. If the final specification includes features or formats not present in the current DVD specification, existing DVD players may not be able to play new DVD Audio discs.

Most scratches will cause minor channel data errors that are easily corrected. A common misperception is that a scratch will be worse on a DVD than on a CD because of higher storage density and because video is heavily compressed. DVD data density is physically four times that of CD-ROM, so it's true that a scratch will affect more data. But DVD error correction is at least ten times better and more than makes up for the density increase. Major scratches may cause uncorrectable errors that will cause an I/O error on a computer or show up as a momentary glitch in DVD-Video picture. However, there are many schemes for concealing errors in MPEG video.

On the market (at stores such as Best Buy) are disc cleaners and disc repair kits which seem to work pretty good. One of the tricks we use here is toothpaste. Not the gel type but the paste. Wet a linen cloth (nothing abrasive) and a little paste and in a gentle, circular motion (from the inside out) carefully buff the disc. If you are to aggressive, you can damage the disc more. The laser reads pits on the disc and has a coating to protect them. If it is just the coating, this should resolve minor scratches that cause skipping.

Consider that laserdiscs, music CDs, and CD-ROMs are likewise subject to scratches, but many video stores and libraries rent them.

The primary advantages of DVD are quality and extra features. DVD will not degrade with age or after many playings like videotape. This is the "collectability" factor present with CDs vs. cassette tapes.

Manufacturers are worried about customers assuming DVDs will play in their CD player, so they would like the packaging to be different. However, no one is being forced to use a larger package size and many companies will undoubtedly use standard jewel cases. It remains to be seen if any package becomes standard, especially for DVD-ROM.

Dual-layer discs are already available. Some replicators plan to produce double-sided discs, dual-layer discs, and double-dual discs from day one. Obviously the prices will be higher, but certain producers already require more space than is available on a single side or single layer.

All DVD players and drives will play dual-layer discs -- it's required by the spec's. All players and drives will also play double-sided discs if you flip them over. No manufacturer has announced a model that will play both sides. Since discs can use two layers instead of two sides, the added cost in the player is not justified.

You are watching a picture intended for display only on a widescreen TV. You need to go into the player's setup menu and tell it you have a standard 4:3 TV, not a widescreen 16:9 TV. It will then automatically letterbox the picture so you can see the full width at the proper proportions.

Most DVD-Video discs contain Dolby Digital soundtracks. However, it's not required. Do not assume that the "Dolby Digital" label is a guarantee of 5.1 channels. A Dolby Digital soundtrack can be mono, dual mono, stereo, Dolby Surround stereo, etc. Some DVD packaging has small lettering under the Dolby Digital logo that indicates if there are 5.1 channels. In some cases, there is more than one Dolby Digital track: a 5.1-channel track and a track specially remixed for stereo Dolby Surround.

Yes. Some CD-ROM drive manufacturers plan to cease CD-ROM drive production after a few years in favor of DVD-ROM drives. Many already have. Because DVD-ROM drives can read CD-ROMs, there is a compatible upgrade path.

DVD will probably replace laserdisc players, but not for a very long time. Laserdiscs are well established as a videophile format. There are over 9,000 laserdisc titles in the US and a total of over 35,000 worldwide that can be played on over 7 million laserdisc players. It will take DVD many years to reach this point. Until then laserdisc has the superiority of tenure. Laserdisc companies have committed to supporting it for years to come. There's no reason to stop buying laserdiscs, especially rare titles that may not appear on DVD for a long while, if ever. Even laserdisc owners who buy DVD will not immediately replace their collection. Laserdisc and DVD will co-exist for a long while.

Currently, HTDV is not directly supported by DVD-Video. HDTV standards were not finalized when DVD was developed. Since most HDTV systems are based on MPEG-2, it could be easy to "upgrade" the DVD format. The upper-end DVD players will convert video from existing discs to the standard-resolution progressive scan DTV formats.

HDTV sets appeared in 1998 at very high prices. It will take a few more years before even a small percentage of households have HDTVs. Those who postpone purchasing a DVD player because of HDTV are in for a long wait. At some point there will be an "HDVD" format, probably around 2003 at the earliest. HDVD players will play current DVD discs, and will make them look even better on HDTV displays. Ironically, DVD-ROM computers will support HDTV before DVD-Video players, since 2x drives coupled with appropriate playback and display hardware can already meet the requirements of HDTV.