DVD Primer

What is DVD?

Bet you thought it was Digital Video Disc. Yes, that’s what it was in the beginning, but then some of the manufacturers tried to change the ‘V” to “versatile” because the format can do so many things. Whether you call it a Digital Versatile Disc or not, it can still provide super video, audio and data storage and access — all on one disc. Like CDs and CD ROMS, DVDs are a high capacity multimedia data storage medium. A DVD can accommodate a full length movie at twice the resolution of VHS tape. It can provide content rich multimedia or very high quality multi-channel audio and video.

Can I play CDs on my DVD player?

Yes, most DVD home players and computer drives will play audio CDs and CD-ROMs. The physical dimensions are identical to compact discs. But in these early days of the DVD format, there is quite a lot of incompatibility among all the different DVD and CD formats so never assume a DVD will work in your hardware. Check it out first.

Will it dominate the home market?

There’s a lot of hype about DVD such as “The fastest growing consumer product in history…” and “DVD will revolutionize the entertainment industry…”. Both statements are probably exagerations. DVD is not a revolution. It is an evolution. Nonetheless the market for DVD has grown faster than either CD or VHS did in their first two years. There’s little doubt this format will replace standard VHS cassettes as the home video standard. One study predicts this will happen before 2005. A quick survey of my local Circuit City revealed that most new computers now come with DVD drives. Many of them also had CD writable drives.

How does DVD technology differ from CD?

Like CDs, DVDs store data in microscopic grooves which spiral around the disc. All DVD drives use laser beams to read these grooves: Tiny reflective bumps called lands and nonreflective holes called pits aligned along the grooves represent the ones and zeros of digital.

DVDs use smaller tracks which are 0.74 microns wide, compared to 1.6 microns on CDs. And then there’s some technical stuff like modulation and error correction methods which allow DVDs to store seven times as much data as a CD.

How do the various DVD formats differ?

DVD Video

For viewing movies and other visual entertainment. The total capacity is 17 gigabytes if two layers on both sides of the disk are utilized.


DVD-ROM

Its basic technology is the same as DVD Video, but it also includes computer-friendly file formats. It is used to store data. DVD-ROM is quickly replacing the CD-ROMs found in nearly all computers. CD-ROMS will go the way of floppy drives.

DVD-R

Like the CD-R format, users can write to this disk just once. Originally designed for professional authoring, a version for consumer use is being developed. This format has a capacity of 4.7 gigabytes.

DVD-RAM

This makes DVD a virtual hard disk, with a random read-write access. Originally a 2.6-gigabyte drive, its capacity has increased to 4.7-gigabyte-per-side. It can be re-written more than 100,000 times.

DVD-RW

Similar to DVD-RAM except that its technology features a sequential read-write access more like a phonograph than a hard disk. Its read-write capacity is 4.7 gigabytes per side. It can be re-written up to about 1,000 times.

DVD Audio

The latest audio format more than doubles the fidelity of a standard CD and has a larger capacity. It may well become the most popular audio disk.

Is DVD Multi a new format?

DVD Multi is not a new format, but it is a set of specifications that will define which drives will read and write which disks for the various DVD consumer and computer applications. DVD Multi is targeted at providing broader compatibility across DVD disks, and will embrace all existing format versions.

What are the Benefits of DVD?

High quality – VHS videotapes are an inprecise analog storage media. DVDs aremade of ones and zeros so the information delivered is exactly the same information that was recorded. There is no generation loss. The resolution of DVD video is almost twice the resolution of standard VHS videotape.

Of course to see this resolution you will need to view it on a high resolution television set, but even on an old set you will appreciate the benefits of DVD. (you may need a $30 RF Modulator from Radio Shack unless your set has RCA

The DVD disc is not physically touched while it spins in the player, so there is no wear and tear or loss of fidelity over time. In contrast, videotapes ride on video heads and rollers and eventually the tape wears and the quality of the video suffers.

Random access – Feature length movies are meant to be viewed from end-to-end. But it’s a rare audience that views a seminar, wedding video, training session, or home movie from start to finish. With DVD, it’s possible to jump instantly to any content at any time.

Permanent storage – It’s a fact that videotape deteriorates over time. DVD is an inherently more stable and permanent medium. DVD is now in common use for archival storage, and studies have shown that there is no theoretical limit to the life of information on DVDs.


Interactivivity – With DVD, the viewer is in the driver’s seat. DVD makes it possible to jump around, to replay favorite sequence, and to skip material you already know. With a DVD, you can use menus and chapter points to let the viewer decide what to view and when. Even the DVD I have of The Maltese Falcon has menus and includes trailers of other Bogart flicks as well as the history Film Noire and more.

Beyond video – DVD-Videos discs can store top quality audio, still images, and other multimedia assets in addition to video. DVDs can include direct web links. Indeed, DVDs make it possible to assemble and publish large collections of high-quality multimedia content in an interactive, flexible form, opening the doors for new applications in every industry. And DVD is perfect for the new video games with so much realistic video content.

What else can DVD do?

Audio streams – DVD supports up to 8 different audio streams, and with the push of a button a viewer can switch to any alternate stream without interrupting the video flow. Multiple audio streams were designed so a single DVD could have several language tracks, but DVD authors have also used the audio tracks to provide features such as a running video commentary.

Subtitles – DVD supports up to 32 sets of subtitles. These were intended for traditional language subtitles, but in reality subtitles can display any image, not just characters. As a result, subtitles today are now used to provide a variety of video effects in addition to text, for example providing highlights in training videos to direct the viewer’s attention. On The Maltese Falcon DVD I mentioned above, you can set it to show French subtitles while the movie plays in English. (If I’d had this in High School my grades might have been quite different!)

Chapter points – Points can be defined within DVD video to mark “chapters” — logical break points within the movie. The viewer can then quickly jump forward to the next scene, or back to replay a scene from it’s exact beginning. Yes, my Maltese Falcon DVD has these and they’re actually pretty helpful for finding your way around the movie.

Interactive control – DVD is designed to be used with a controller that has a set of standard button functions. Using this controller, the viewer can switch seamlessly from one camera angle to another, skip forward (or back) to the next (or previous) chapter point, fast forward and rewind, play slow-motion, change languages or subtitles, jump to the last menu or the title menu, and more.

Camera angles – DVD can support up to 9 “camera angles”. These are used when presenting any video content where multiple camera shots are available and it would enhance the viewer’s experience to be able to change his view of an event or action scene. For example, within a training video a mechanical assembly process could be shot and then viewed from several perspectives.

Aspect ratio – DVD can support both the 4:3 TV screen format aspect ratio and the increasingly popular 16:9 HDTV screen format. The wide screen format is especially popular with corporate users creating interactive kiosks.

Parental lock – Parents can configure their DVD player to prohibit viewing versions of movies with unacceptible ratings for which range from the director’s cut, to R-rated, to PG-13.

What are Region Codes?

They’re also called “regional codes,” “country codes,” or “zone locks.” The movie studios want to control the home release of movies in different countries. Each DVD Video Player is given a code for the region in which it is sold. And the DVDs can be coded to play only in certain countries. Not all discs have these region locks, but those that do can only play in the country or region which it was programmed for.

The eight regions are:

1: U.S. and Canada

2: Japan, Europe, South Africa, and Middle East including Egypt

3: Southeast Asia and East Asia including Hong Kong

4: Australia, New Zealand, Pacific Islands, Central America, Mexico, South America, and the Caribbean

5: Eastern Europe, Russia, India, Africa, North Korea, and Mongolia

6: China

7: Reserved

8: Special international venues such as airplanes and ships.

The bottom line is you should always check the label on DVDs you purchase.


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