Last Friday we were treated to some never-before-seen artifacts related to development of the CED VideoDisc format at RCA.

The New Jersey Antique Radio Club meets at Sarnoff Corporation in Princeton (the old RCA labs.) We're fortunate to be able to conduct our meetings at such an appropriate historic location. And we're blessed with such convenient access to the wonderful resources of the David Sarnoff Library archives.

Alex Magoun, director of the Library, cobbled together what was billed as the first-ever display of rare CED developmental artifacts from the Library's vaults.

Here's a video (http://www.njarc.org/streaming/) of this amazing presentation.

(Alex's presentation is item #12 on the list for "October 2007 Meeting" at the top of the page. You might also enjoy item #11 in which club member Rob Flory showed us an Iconoscope his grandfather made at the labs in 1932!)

That's pretty cool. I once owned a stereo CED player and a handful of discs. One of the local video stores even rented them. The audio was fantastic, the video wasn't all that much, about the same as VHS or early CX LD's.

I've been playing around with my pair of CED players this week. It's sad to think of the tremendous efforts that went into engineering these things, and that the whole project basically layed an egg. I guess that was the last great effort to come out of RCA?

Yeah, I think so. Although RCA continued making some very nice sets for several more years afterwards. VHS's ability to record is what killed the CED format and to face facts, RCA should have made the CED players better. Mine was prone to act goofy and skip. The cheap plastic lightweight platter didn't help things in that regard.

When I first opened up the players I thought the platter was cast metal, but then I saw otherwise. I just replaced the stylus advancing belt, which helped, but the better of my 2 units still skips every so often. I think my other one needs a drive belt. When things are working correctly they do put out a very decent picture (for their age.) Something I really like about these is that they are made in the USA. A real last-gasp.

I think laser disk is what really killed CED. It came out before CED and had a better picture with stereo sound (although early LDs aren't much better than CEDs). CED was obsolete before it came out, but they put too much money into it to just scrap the idea.

What was odd (at least around here) was that CED's were fairly common and even sold in some chain stores, whereas at the time, pre-recorded VHS, Beta and LD's were fairly scarce. It was at least 1982 before pre-recorded VHS became common around here (excluding of course the video rental stores). My first VHS deck was a Panasonic that recorded and played back Dolby Stereo on linear tracks. Shortly afterwards, VHS Stereo Hi-Fi came out. (Don't know why I felt the need to throw that out...I just did.) :D

Maybe it's my failing memory, but I seem to remember that the CED's were about $30-$40, where VHS was about $80 for prerecorded in the 81-82 timeframe. I remember the hoopla about Star Wars coming out on VHS for the unheard of price of $50, and then they were soon trumped by Top Gun for $30 because it had a Pepsi commercial on it, starting a problem all of its own. There were no LD's in the lower Mississippi Delta to speak of back then, it was entirely a VHS/CED market. LD was a science fiction expensive fantasy! VHS rentals were almost entirely what people down here did, and very very few actually bought movies on tape, expense being the issue. Is this familiar to anyone else or am I just senile?

I think CED movies may have been $25 and $30, which would be $5 less than comparable Laser Disc versions. Prerecorded movie tapes started at US$60 for the first group (all Beta) from Magnetic Video in about 1978. Later, they started to go up to $80 and eventually often $100, as the studios priced them for the rental stores since there was no revenue-sharing back then. Star Trek 2 was the first tape priced lower with consumer sales in mind, at US$39.95. The next low price was Raiders Of The Lost Ark at $29.95, and it included a commercial for the upcoming Indiana Jones And The Temple Of Doom, which was also on the Laser Disc, the only LD to ever get a commercial that I know of. These releases were in 1982-83, and low-priced tapes remained the exception all through the life of VHS and Beta. Top Gun in 1986 was notable as the first tape with a true non-related commercial, but the excuse was that it "allowed" the price to be $30 as ha1156w said. CED during its short life was always easier to find than Laser Discs, primarily because it was available from more manufacturers, starting with RCA of course. Laser Disc players were only made by Pioneer and Magnavox in those days. CED players were also less expensive, starting at US$300 if I remember right versus LD players at $600 or more, until Pioneer came up with a stripped-down $400 model.

I think CED movies may have been $25 and $30, which would be $5 less than comparable Laser Disc versions. Prerecorded movie tapes started at US$60 for the first group (all Beta) from Magnetic Video in about 1978. Later, they started to go up to $80 and eventually often $100, as the studios priced them for the rental stores since there was no revenue-sharing back then. Star Trek 2 was the first tape priced lower with consumer sales in mind, at US$39.95. The next low price was Raiders Of The Lost Ark at $29.95, ...

Man, I forgot about the "low-priced" Raiders-- it may seem funny now, but that really did create a sensation of sorts at the time-- $29.95 was really cheap for a popular 'current' movie on videocasette at its time.

Chris is absolutely right about the relative prices of prerecorded videocasettes versus CEDs. CEDs were a lot less expensive. My parents got their first VCR in 1979 (a Toshiba Betamax-format unit), and prerecorded tapes were *very* expensive to buy. [Even blank tapes cost nearly $20] I remember us actually buying _The Muppet Movie_ on video when it came out (for Christmas 1980, perhaps..?); I think it was $89 or so. We must have watched that tape a zillion times though! :) I remember seeing _The Muppet Move_ on a newer VHS release in the late 1990's, but it somehow just wasn't the same without the cheezy Magnetic Video title 'fanfare' at the beginning. :)

I have a few Magnetic video Beta tapes. I remember that one of them was recorded out of alignment.

RCA should have made the CED players better. Mine was prone to act goofy and skip. The cheap plastic lightweight platter didn't help things in that regard.

The reason for the skips and goofy action was impurities and dirt in and on the disc itself. They had a firmware mechanism for getting out of "locked grooves" but nothing to force it back to get the video skipped over if a piece of dirt kicked the needle forwards. I knew one of the guys developing this stuff, and he said that it wouldn't have been a big deal to write the code to do that, but some bozos in management wanted to freeze the design as is and ship it...

Well, that figures...

I was working in an Audio/Video type store when these came out, I remember the hype and I remember the huge disappointment at the picture quality, especially compared to the Laser Discs which this store sold.

They had weird artifacts in the picture, maybe they improved later but it was a noticiable flaw at the time.

The reason for the skips and goofy action was impurities and dirt in and on the disc itself. They had a firmware mechanism for getting out of "locked grooves" but nothing to force it back to get the video skipped over if a piece of dirt kicked the needle forwards.

I wasn't aware that a software 'fix' was even considered or possible for that, but yeah, if you get an old well-used CED disc (like one that was originally a rental), they tend to skip all over the place-- especially the first time you play the disc after it has been sitting for a while.

Anyway, if your CED player skips badly and acts goofy the first time you play a particular disc-- but improves dramatically if you go back and start playing it again-- then the problem is dirt and dust stuck to the disc (a.k.a. the CED "video virus"). On the other hand, if your CED player skips a lot on all discs no matter what, then the problem is more likely that the stylus is worn.

Does anyone know any technical specs for CED such as how the video and audio are modulated? Whar carrier frequencies are used and how do they compare to LD, or VHS? How is the color encoded? What's the resolution?

Does anyone know any technical specs for CED such as how the video and audio are modulated? Whar carrier frequencies are used ? How is the color encoded? What's the resolution?

They used FM to encode the video onto the disc, very similar to methods used on videotape. The audio was FM modulated onto another carrier, and for stereo, they used a 2nd FM modulated carrier for L-R (I don't remember what the frequencies were). They put the chroma subcarrier at around 1.5Mhz and mixed it in with the video luma, and the player upconverted it up to 3.58MHz after using IIRC a line comb filter. The luma resolution was about 3Mhz, better than VHS tape, but worse than laserdisc (4MHz).

They used FM to encode the video onto the disc, very similar to methods used on videotape. The audio was FM modulated onto another carrier, and for stereo, they used a 2nd FM modulated carrier for L-R (I don't remember what the frequencies were). They put the chroma subcarrier at around 1.5Mhz and mixed it in with the video luma, and the player upconverted it up to 3.58MHz after using IIRC a line comb filter. The luma resolution was about 3Mhz, better than VHS tape, but worse than laserdisc (4MHz).

So, it's not composite like LD. I wonder if an S-video output could be added?

So, it's not composite like LD. I wonder if an S-video output could be added?

It is a strange kind of composite video, where the chroma subcarrier is at around 1.5MHz instead of 3.58 MHz. They did that partly because they didn't have enough bandwidth to have it at the usual 3.58MHz. This also allowed them to remove the effects of wow and flutter (from the turntable spinning at 60/8 times a second) by varying the beat frequency used to shift the chroma subcarrier from the 1.5MHz to 3.58Mhz. The resulting 3.58Mhz would be compared to a local reference crystal and the error would then shift the beat frequency up or down to correct it. A little like a PLL (phased lock loop). The beat frequency was about 5.11MHz, beat that against the 1.5MHz and you get 3.58MHz.

In a sense, there's no overlap in the luma and 3.58MHz chroma, as the luma bandwidth cut off around 3MHz, and the chroma bandwidth was about 600KHz. You can still sometimes see cross luma into the 1.5MHz chroma, though. Nothing you can do about that, as it's that way on the disc.

As wa2ise says, it used a comb filter. It had to, or the low frequency color carrier dot pattern would ruin the picture on anyting except gray objects. I believe the source was also combed before encoding to (mostly) prevent luma from getting into the color. The comb filtering attenuated diagonal details. They had a demo disk including a drive across a suspension bridge, and some of the diagonal wires got pretty indistinct.

Another pitfall of the CED format was the silicon lubrication that they misted the disk with when manufactured to reduce friction and increase lifetime. Over time it evaporates/deteriorates/rubs out in the caddy/whatever. Has anyone in the enthusiast circles figured out a way of renewing it?

The stylii were a wierd multi-angle affair that really skated across the surface, and using an electrode on the leading face, read the varying capacitence of the disk. Word has it that one of the original lapping machines is still stored somewhere in one piece but with the recent sale of Thomson's consumer electronics division to various sources, they may have finally let go of it. Once the stylus supply dries up, there's no more. Ever.

Seems as though somewhere on the CED Magic site I saw a link to a place that rebuilds the stylus. A good idea to have spares, either way.