MCA DiscoVision

Popular Electronics
March 1981

Entertainment Electronics
Life with Video Discs
by Ivan Berger

There is probably still time to be the first on your block with a videodisc player - if you want to be. Magnavox and Pioneer have just put their laser-scanned disc players into more or less national distribution, and they'll still be a novelty in many areas. Even if someone beats you to the punch, you can still be the first with an RCA "CED" disc player or a Japanese-developed "VHD" player, both of which are due by about the time you see this. I had a Magnavox for a test about a year ago and have the Pioneer player here right now. They're fun to have. But whether you'll find them worth buying will depend on as many personal factors as technical ones.

Why have a videodisc that just plays programs when you can get a tape deck that records them, too? It's really the same question as "why have a phonograph when a cassette recorder is available?" and the answers are just about the same. Like the phonograph, the videodisc can give you the best reproduction available. For example, I've gotten resolution better than 300 lines (horizontal) from a much-played video test "record," while the best I've seen on recent VCRs was about 250 lines. The disc picture was also far freer of snow and other noise, and there was no color smear, a common fault with tape. Of course, there is some noise and loss of detail. In fact, a really good broadcast or cable signal would give a better picture. I confirmed that by comparing a broadcast test pattern with that from my video test disc.

When it comes to sound quality, the laser-scanned video disc (the only type we've worked with to date) runs rings around the VCR and may even beat what comes off the air. The audio signal is stereo, with enough separation for bilingual use, as well. Stereo-sound VCR's are just now appearing (Akai's is the only one I know) and stereo TV broadcasting must await an FCC decision.

What's more, all the special effects work better on the disc than on a VCR. Still-frame, for example, is free of jitter, blur and noise bars. Speeds range from normal down to a slow-motion 12 frames per minute (1150 normal), and there are two fast modes - one at three times normal speed for reviewing or previewing a portion of the program - and one that zips through the entire disc in less than 30 seconds. All functions operate as smoothly and cleanly as normal play, and in both forward and reverse.

The videodisc frame counter puts the ones on VCRs to shame. Instead of an arbitrary four-digit number half-hidden behind a little window, there's a five-digit number on the screen (when you want it there) that identifies every one of the more than 50,000 frames on each side. On the Pioneer (but not the Magnavision), you can even punch in the frame number and have the player find it for you. Some discs have chapter numbers to help you find sections rather than frames. They can even carry signals that stop the player at each chapter's end (frame-by-frame access is coming to home VCR's though.)

Otherwise, videodisc has much the same advantages and disadvantages compared to tape as the phonograph does. Disc software is cheaper to manufacture than prerecorded tapes, and access to stored information is much faster random rather than sequential.

But if the videodisc shares the phonographs advantages, it has its major disadvantage as well: reliance on program material from outside sources, rather than on user-made recordings. That's important for two reasons: first, since the phonograph preceded tape, there was already a vast library of recordings available with the latter hit the scene. Videodisc is a Johnny-come-lately, and most of what's available is on tape, not on disc. Second, with three incompatible disc systems contending for market share, the odds are against picking the one that will survive.

If you could make your own discs, that would be a small problem. If a video tape system becomes obsolete, there will still be enough demand to keep blank tapes available for years - suppliers can sell the same blanks to everyone, regardless of their tastes in programming. But once a disc system dies, don't expect suppliers to produce new program discs indefinitely.

How will the two new systems - RCA's CED and the Japanese VHD - compare? RCA's disc will initially have only monophonic sound. This is not as much of a drawback as some critics claim, I suspect, since so little video material with stereo is yet available. It also won't allow still-framing and some of the other fancy features of the laser disc. On the other hand, there are reports that the VHD disc will require extra "frame-store" circuitry to do still-framing. And the long-play (CLV) laser discs, which have 60 minutes per side instead of the standard (CAV) discs' 30, don't allow still-framing, frame number display, triple-speed play or frame number search. (There is a counter readout but it shows minutes and seconds rather than frames.)

Projected costs for both CED and VHD are lower than the laser disc's. RCA says its CED disc player will sell for $500; presumably, the rest (from Zenith, Hitachi, Radio Shack and others) will cost about the same. On the VHD side, Sansui (which just announced a player for later in '81) says the cost will be "at least $200 less than laser disc players," in other words about $550-$600. But discounts are available already, here and there, even with just two laser players on the market; with more competition, more price cuts are likely.

There's no telling how VHD and CED discs will compare with the laserdisc for reliability. The laser-system disc seems the most long-lived, on paper (no physical disc contact, for one thing), but it has had problems. Early discs, on early players, would occasionally loop back to repeat a segment of the program, or stop altogether. There have been rumors of a high rejection rate at MCA's disc plant, and dealers have reported as many as one-third of their discs being returned. But disc production techniques have now improved (the return rate is now "almost as low as audio discs" says Magnavox), and Magnavox has modified its new players and those already in the field to eliminate the problem. A new laser-disc plant is rising in Japan, for Universal-Pioneer (the Pioneer player's actual manufacturer); if it lives up to the Japanese reputation for quality audio disc pressing, there should be no further problems.

How do the Magnavox and Pioneer players compare? Quite closely. I used them several months apart, so I can't say for sure that there was any difference in performance between the two. My Magnavox (an early, unmodified one) did sometimes skip into a loop on one specific disc side, and my Pioneer doesn't seem to have that problem. The Pioneer does have some extra features, though, such as the random-access system, a clever remote control (wireless, but with a wired option, in case it uses the same signal frequencies as your TV set), and a rear-panel jack for a potential digital-audio disc decoder.

That digital-audio outut raises another idea that should intrigue computer enthusiasts. Estimating from the bit content of digital audio, a half-hour disc could hold about 150 megabytes, roughly the same as a 14-inch hard disc (allowing for redundant bits and the like). Track-to-track access would be a bit slower than disc systems designed for computer use, but a worse-case access time of about 30 seconds, on a data store that big, would be acceptable, especially for hobbyist applications. Coming up, though not soon, are laser-disc systems that record as well as play. That would turn the videodisc into a cross between hard disc and super ROM, with more capacity than most microcomputer users ever dream of.

Digital audio discs will probably be using that output long before computers are. But don't be too sure. The one laser based audio disc system I've seen concrete proposals on is Philips' Compact Audio Disc. It uses the same technology but is incompatible with the current video disc players. Should the industry choose that (and Sony is already hacking it), the digital outputs on the pioneer player won't be much use - which Pioneer admits "We don't know where the industry is going - nor does anybody else - be we wanted to leave as many options as possible open ...," says Pioneer's John Talbot.

If all this leaves you a bit confused, you're not alone. So are the manufacturers. Sansui, for example, while announcing its VHD disc player (with provision for VHD-compatible AHD audio discs which have three digital sound channels plus still pictures), also announced its conversant with both RCA's CED videodisc system and the Philips Compact Disc audio system, and could produce either (or both) if the market seemed to warrant it.

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