DVD How will the next quantum leap in audio and film technology play with those raisd on CDs or burned by Beta?


Thanks to DVD, the future of home video has never seemed brighter. Or sharper.

Touted as the greatest breakthrough in entertainment gadgetry since the compact disc, DVD (which, depending on whom you ask, stands for either Digital Video Disc or Digital Versatile Disc) makes VHS tapes or laser discs look positively antiquated. DVD delivers a crisper, more detailed picture than either of them. Moreover, DVD can fit an entire film on a disc the size of a CD, while offering features beyond anything offered on previous generations of video players.

Want to hear "Terminator 2" dubbed in French? Push the "audio" button on your remote, and you can switch from English to French, or Spanish. Need subtitles? Use the "subtitle on/off" feature to turn them on, and the "subtitle change" button to choose which language you want. Viewers can also choose to watch "T2" with the wide-screen picture people saw in theaters, or in the "pan-and-scan" version used for TV broadcast.

Nor are those the only features available with DVD. There's a parental control option that can allow parents to set the machine so it will check a film's MPAA rating and not play NC-17 or R-rated films (parents can choose the cut-off point) without a password. Some DVD discs even offer a multiple-angle option, so the viewer can change the camera angle while watching. DVD players may also be used to play music CDs, but not CD-ROMs.

Most amazing of all is that this technology has arrived on the market at a surprisingly affordable price. DVD players are available for as little as $500 -- much less than first-generation CD players or VCRs -- while most discs are priced between $20 and $25.

Discs may also be rented, though not everywhere. Blockbuster has introduced DVD rentals in about 100 stores nationally, including four in the Baltimore suburbs. There are also a few independently owned shops, such as Cranbrook Video in Timonium, that rent the discs.

DVD, which was developed by an industry consortium, has the support of all the major home electronics manufacturers. Sony and Toshiba have been the most aggressive in marketing the machines, and since DVD's launch in March, more than 100,000 players have been sold in the United States, a figure manufacturers predict will have doubled by spring. There are more than 400 movies and music videos available on DVD, and the number continues to grow.

Still, for all its promise, DVD is likely to leave consumers with a few questions. For instance, how does it work? What are its drawbacks? And how can we be sure DVD won't end up like Beta and quad, forgotten in the scrapheap of entertainment technology?

How it works

Looking at a digital video disc, it's hard to believe it can hold so much information. After all, a CD can barely handle more than 74 minutes of music. But even though it's exactly the same size, a DVD can hold a full-length feature film and still have room for extras. How can that be?

The answer has to do with the way the information on the discs is stored and read. As with CDs, a laser is used to scan the surface of the DVD for microscopic pits. By reading the pits and smooth surfaces as ones and zeros, the laser generates a digital bitstream, which is then decoded into audio and video signals.

One way DVD squeezes more data onto the disc is by using smaller pits and placing them closer together. This is possible because DVD players use a different kind of laser -- the shorter wave-length "red" laser -- than CD players.

Another advantage DVD has is a video compression system called MPEG-2. Basically, what video compression does is sift through the visual information in each frame and delete unnecessary information.

To understand how that works, imagine a movie that shows someone walking through a door into a room. The only parts of the image that actually "move" are the door and the person coming through it; everything else in the room -- the walls, the furniture, the decorations -- remain unchanged.

Now, a piece of film "redraws" the whole image -- both moving and non-moving parts -- 30 times per second. It makes for a vivid visual, but it contains a lot of repetition, something digital engineers consider "redundant data." So what MPEG-2 does is carry over the background information, so the player doesn't have to redraw the entire scene with each new frame. It just draws the changes, saving storage space. Meanwhile, the viewer gets virtually the same effect.

Another difference between DVD and CD is that CDs are one-sided, whereas DVDs can use two sides to store data. All told, DVDs can store up to 13 times the amount of information a CD holds. Whether a movie uses one or two sides of a DVD depends on the amount of features included in the package; most fit on a single side.

Pros and cons

Of all the advantages DVD has over other video players, the most obvious is picture quality. Not only does DVD offer a higher line resolution (more lines per screen) than VHS or laser disc, it also offers greater color separation.

Just how much greater depends on the player and the TV to

which it's connected. Most TVs of recent vintage have what's known as a composite video connection on the back, a standard jack like the ones found on the back of stereo equipment, an RCA jack.

Video signals arriving via this kind of connection go through a "comb filter" inside the television, which separates the signal into yellow, red and blue signals, which then flash on the screen. Trouble is, some data gets lost in the combing process, reducing sharpness of the image.

That's why many DVD players include several other video inputs. Most common is a four-pin connector called an S-video input connector, which sends the image along pre-separated, so there's no need for the comb filter inside the TV. Some DVD players even include component video input connectors, which offer an even higher-fidelity separation.

Trouble is, these connectors won't do you any good unless your TV has corresponding input jacks. S-video connectors are found on most current, mid- to high-end TV sets, but component connectors turn up only on the expensive monitors or projection TVs. Before buying a DVD player, it's worth checking the back of your TV to see what sort of input it can take.

On the audio end, DVD players are advertised as offering CD-quality sound. While this is true enough, many DVD players sound only as good as low-level CD players. That won't be a problem for many listeners, as it represents a vast improvement over VHS, but audiophiles may find that DVD sound isn't quite as stunning as its visuals. So far, the only DVD player to rate consistently high marks from audio critics has been Sony's DVP-S7000, which retails for about $1,000.

Still, DVD is a real blessing for serious film fans. Unlike videotape, which requires endless fast-forwarding to find a specific scene, DVD allows viewers to call up illustrated indexes on the screen so they can skip directly to the scene they want. It's also great for foreign films, such as "La Femme Nikita," because the viewer can choose between the original soundtrack or an English-language dub (and, in the wide- screen format, "La Femme Nikita" keeps the subtitles down in the black area below the picture, so nothing is obscured).

Finally, remember that even though DVD players are capable of playing all sorts of special effects, you won't see them unless they're built into the software. Not every disc offers a choice of languages, nor do they all allow the viewer to choose between a wide- screen or a pan-and-scan image.

Look at the package to see what features each disc has before playing it, as few things about DVD are as disheartening as pushing a button on the remote, only to see the words "THAT FUNCTION NOT AVAILABLE" flash on the screen.

What the future holds

If the DVD picture looks bright on the home video front, its future is murkier in other formats.

One of the reasons DVD is sometimes referred to as a Digital Versatile Disc is that DVD technology could also be used in computers and stereos. DVDs can hold more than 10 times as much information as CD-ROMS. Unlike CD-ROM discs, which store a mere 650 megabytes of data, first-generation DVD-ROM discs can hold 7.7 gigabytes. Eventually, DVD-ROM discs may hold as much as 17 gigabytes of data.

At the moment, however, DVD-ROM discs aren't holding much of anything. Although there are some DVD-ROM drives on the market at the moment, most software companies are holding back on the discs, waiting for the pro-jected midsummer launch of Windows '98.

Moreover, there is no DVD equivalent to the recordable CDs currently on the market. A recordable/erasable disc, the DVD-RAM, is promised, but industry squabbling over format standards suggests that it will be some time before recordable DVDs are as useful or universally compatible as recordable CD-ROM drives.

Meanwhile, audiophiles are arguing over how DVD technology will be applied to sound recording. One group advocates a format called linear pulse-code modulation, while another -- led by CD inventors Sony and Philips -- are advocating a multi-channel format called Direct Stream Digital. Although a compromise between the two formats is being sought, no quick resolution is in sight.

Finally, there's a competing video format in the works called Divx. Developed by Circuit City in conjunction with manufacturers Matsushita, Thomson and Zenith, Divx discs would be sold for $5 and would offer unlimited viewing for a period of two days. After that, a modem inside the player would connect to a central computer, billing the customer each time the disc is played.

Divx players would start at about $600 and would also play

standard DVD software. Howeveer, DVD players would be unable to read Divx discs.

So far, Divx has the support of Paramount, Universal, DreamWorks and Disney. In fact, Disney insists its animated features would be available only on Divx. But despite promises that Divx would be in stores by Christmas, the machines will not hit the market until sometime next year.


Here are some terms that will help you understand DVD technology:

DVD: A 5-inch disc capable of holding up to 4.7 gigabytes of audio and video information. DVD can stand for either Digital Video Disc or Digital Versatile Disc.

DVD-ROM: A 5-inch data storage disc, similar to DVD, but capable of holding up to 7.7 gigabytes of information.

Gigabyte: One million bytes, a byte being the unit of memory or data used to represent one character on a computer screen. Megabyte: One thousand bytes.

MPEG-2: The video format used on DVD. MPEG is an acronym for Motion Picture Engineering Group.

Pan-and-scan: A video editing format that reduces a movie image from wide-screen size to the squarer dimensions of a TV screen, so-called because it either pans across the wide- screen image or scans only its center.

S-video: A four-pin video connection found on some TVs and most DVD players. It offers better video separation, and thus a sharper picture, than standard composite plugs.

Pub Date: 12/15/97

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