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DVD: Die, VHS, Die

By Rich Moraski
12 October, 2001

It’s no secret: VHS movies don’t look very good. The format turns 25 this year, coming from an era of console TVs. You remember those monstrous pieces of furniture with one little speaker in them. Though Betamax was a superior format, it didn’t catch on (in the consumer market, anyway), mostly because the tapes weren’t quite as long as VHS cassettes.

No no, we’re in the Digital Age now, God help us, and we need something better. DVDs to the rescue!

Digital Versatile Disc

Though it looks suspiciously like a CD, a DVD packs a lot more information. They can be two sided, and can have two layers on each side, for a possible grand total of 9.7 gigabytes of information (compared to 650 megabytes for a CD). That’s roughly 15 times as much storage, providing plenty of room for a movie with a killer soundtrack and several special features, such as The Making Of and biographies of the stars.

That’s all very nice, but the best part is you don’t have to rewind them.

Circuit City, in yet another plot to take over the world, tried to squash DVDs with DivX. In this scheme, you’d buy a disc that looked just like a DVD, but you only got to play it for three days, and only in one player. If you wanted to watch it again, or in another player, you had to pay again. To activate it you were required to make a phone call to Big Brother to get a key. This allowed you to watch the movie while registering your viewing habits with whomever looked at that information. The goal was a captive rental market: buy the movie for $5, watch it for three days, and keep (or throw away) the disc. Fortunately for us, this didn’t catch on, and the format is dead.

All DVD players can play CDs, some better than some high-dollar CD players. While the engineers haven’t completely settled on why this is, it’s very possibly because the motors in DVD players must move the laser in much finer increments, because all that extra information is packed in more tightly. As a result, tracking is better.
The current crop of DVD players are, for the most part, all pretty good. The worst still produces 100 times better video and audio than a VHS cassette. There are a couple buzzphrases to consider when picking out your new toy.

Dolby Digital/DTS decoder

When the final specifications for DVD movie audio formats were being hammered out, a standard needed to be adopted. Dolby Labs, a well known company (unless your name is Jeanine…), had little trouble edging out the up-and-coming DTS format. AC-3 – later Dolby Digital – became the de facto standard for movies. Both formats can produce multiple channels, including surround and dedicated bass channels. Both use some compression, though DTS uses less, thus providing richer sounding bass at the expense of taking up more room on the disc.

Players with built-in decoders will have multiple audio outputs, typically two for the front speakers, one for the center, two for the rear (though sides are preferred), and one bandwidth limited bass channel. If you have a Dolby Digital ready receiver, meaning it has at least one input with multiple input audio channels, then you’re all set. If your receiver has a digital input you can just connect the DVD player to the receiver with a single cable. If you have both, you might want to try out both hookups and see which sounds better (there will be a difference, though it might be very subtle).

Progressive scan

One of the latest big deals in DVD players is progressive output. To help explain what the hype is about, a quick overview of how TVs work is in order.

TV pictures are composed of numerous horizontally drawn lines. Normally these lines are drawn interlaced, meaning that half are drawn first – all the odd lines, for example – then the second half – all the even lines. Each set of lines, or field, is drawn in about 1/60 of a second. So a full screen, or frame, is drawn roughly 30 times per second (29.97 in the U.S., but who’s counting?).

Progressive scan DVD players have the ability to output 60 full frames per second. In order to do this, the TV receiving the signal must have progressive scan capable component inputs. These look like three RCA jacks, labeled either Y, Pb, Pr, or Y, Cb, Cr. The labels don’t really matter: the Powers That Be decided to call them different names for analog and digital input. In practice, they work the same, regardless of what’s going in to them.

There are a few different schemes for making this work. While most of the normal schemes will look just about the same, one important area has to do with reproducing film sources. Movies are filmed at 24 frames per second. DVD information is played back at 30 frames per second. The way normal DVD players handle this is by repeating one field in every five, thus generating 30 frames out of 24. Confused yet?

The details of the above process, called 3:2 pulldown, aren’t as important as the side effects. If some significant movement happens in that repeated frame, the image can get blurry for a moment, as half of the screen is showing the picture before the motion, and the other half is showing the picture after. Progressive scan DVD players recreate the entire frame before sending out the signal. This way one frame in five can be repeated, making everything flow much more smoothly.

The players

All the standard home audio/video names apply here: Sony, JVC, Panasonic, Toshiba (and Theta, Proceed, and Faroujda for those of you not suffering from the market downturn). In the $200 area, Toshiba has a couple models – namely the SD1700 for less than $200, and the SD2705 for slightly more. The latter is a carousel player, just like a 5-disc CD changer. You can put in the entire first season of The Sopranos, hit play, and watch until your eyes fall out. For a little more - $250 to $350 – Sony and Panasonic have a couple entry level progressive scan players. The $400-$600 range will get you into the higher end of mere mortal players, with better connectors, heavier cases, and better power supplies. Or you can go drop $6000 on the Proceed PMDT. It won’t play much better, but it will look pretty damn cool.

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