Affordable 4:2:2 - Digital-S Matures

DTV-Ready sets are due on the market in less than two years. The demand for DTV quality production will grow concurrently. Most anticipated standards of DTV are based on digital component of 4:2:0 which carries half the chromanance of 4:2:2, but is still very high quality compared with today's NTSC format. Producers using 4:2:2 will have the highest quality DTV resolution because 4:2:2 converts nicely to 4:2:0. However, producers using DV formats are shooting in a 4:1:1 format, which already has half the chromanance of 4:2:2. When DV producers convert to DTV, they will lose half their chroma again, resulting in 4:1:0.

In other words, DV producers will be tomorrow's industrial producers when they broadcast, while producers using 4:2:2, will be the new "broadcast quality" kids on the block. The choice in price, $5,000 to $50,000, between DV and Digital Beta is a very great chasm to bridge, threatening upward migration. That chasm has been bridged by a third choice which combines both affordability (cameras in the $12,000 range, decks in the $10,000 range) with quality (true 4:2:2 component digital). The third choice is JVC's Digital-S format.

Digital-S is NOT digital-SVHS. The only commonality between SVHS and Digital-S is the size of the tape (1/2") and the fact that JVC invented both formats. Digital-S is a true 4:2:2 digital component format with 50 megabits per second data rate. This data rate is the minimum required to yield lossless digital dubbing. DV formats, for instance, are 25 megabits and consequently do not yield transparent dubs, free of artifacts. Although DVC-Pro50 operates at 50 megabits, it achieves this by doubling the DV tape speed, which halves the maximum record time, resulting in double the cost of raw stock.

The mild compression ratio of Digital-S, at 3.3 to 1, yields what engineers agree to be a perceptually lossless format, capable of dozens of dub generations, and the tapes run at a full 124 minutes in the camera and in the studio.

Furthermore, future extensibility of the Digital-S into the DTV realm of 720P and 1080i is highly probable. JVC announced at NAB '98 that it will offer 100 megabit Digital-S decks and cameras, capable of 720P and 1080i. Their newest Digital-S camcorders, DY-90SW will be switchable to 16x9, emulating the specifications of Sony's BVW-700 at about a third of the cost.

Tools for Transition

Digital-S is a solution that fits many needs today with strong extensibility to the DTV standards of the near future. A Digital-S edit-recorder makes an excellent transition tool from linear to nonlinear for instance. Many shops currently employ various analog formats, such as S-VHS, Hi-8, Beta and BetaSP, in linear edit systems which are undergoing a transition to linear.

In our own shop, for instance, we are dismantling two linear systems (a Beta-BetaSP and an S-VHS), redistributing the player decks into two nonlinear suites and selling off the surplus record decks on the used market. Each room will have one player of each format and they will both dump to a Digital-S deck.

Because the Digital-S format is lossless and the tapes so long, we can dump both the edit master and the nonlinear galleries to one Digital-S backup tape. Later, if the client wants to revise after the NLE drives have been erased, the task of reacquiring the footage is about as fast as run time, certainly a lot faster than any other kind of archive.

Until now, we've been videotape mastering to our BetaSP decks. Although BetaSP represents a high quality analog format for mastering, however, it is by no means as high quality as the nonlinear systems we are using, (DPS Perception, Targa DTX 2000 and JVC's new Timegate - see separate review). BetaSP cannot serve us in a DTV world and it cannot dub back to the nonlinear system as transparently as a 4:2:2 digital master.

The JVC BR-D85 and BR-D92 edit decks fill this niche very nicely. Priced at about the cost of a PVW 2800 BetaSP deck, including the serial digital interface (SDI) option, the Digital-S decks can be independently operated or controlled by any legacy controller that supports 9-pin RS-422 connectors.

SDI quality represents a significant quality improvement on component video. We proved this to ourselves by employing animation output from an Intergraph TD-425 Studio-Z computer, equipped with both an Intergraph SDI video output card and a DPS Perception video output card. Although the Perception put out excellent component quality, the pure digital, SDI-to-SDI capability of the Studio-Z to Digital-S system could not be beat. We were preparing our animation for large screen projection and every pixel of resolution improvement was apparent. As more SDI-capable gear comes to market (especially at the reduced prices of JVC equipment) we predict a significant decline in component applications, to say nothing of composite or Y-C.
(see Studio-Z sidebar).

The BR-D92 improves on the 85 with two additional, editable audio tracks, front panel edit controls and audio rate converters which allows it to translate 44.1, CD and MD audio into its SDI digital audio format. Users may find that the front panel edit controller, capable of controlling two decks, may be all the controlling that's ever needed. Another included feature of both the BR-D85 and the 92 is pre-read, which is an incredible feature on a deck costing $16,000.

Pre-Read

Until these machines were offered, pre-read was only found on decks costing over $60,000. Consequently, this feature is not well understood by many producers. Pre-read, simply put, allows the edit VTR to act as a source deck at the same time that it acts as the record deck. This is achieved by keeping the play head, the erase head and the record head active during pre-read edits. The play head sends its signal to the SEG (special effects generator) where it is mixed with the signal from the play deck. After the signals are mixed, they return to the recorder and are editing back into the master tape at exactly the same point from which they originated, creating a an invisible matched edit.

In effect, you can create three-machine edit effects with only two machines. Smart edit houses, can use older play decks, like S-VHS, BetaSP, even 3/4" decks, coupled with a JVC pre-read machine to create an vast array of effects. Once the signals are recorded in digital format, they will experience no further image degradation, regardless of how many times a scene is pre-read and fed back onto itself.

We tested the pre-read capabilities of the BR-D85 (editor) and BR-D50U (player) in our online edit suite. We ran the SDI digital outputs of both decks into an Pinnacle Aladdin 601. Since the Aladdin requires a host computer, we chose our Compaq Deskstation 6000 and loaded Pinnacle's StudioPak software into WindowsNT 4.0. Editing control was done with a simple, 2-machine, cuts-only JVC editor. The Aladdin, acting as the DVE, controlled from the mouse of the Compaq, created a wild assortment of effects originating from the Compaq or the BR-D50U player and composited over the pre-recorded background supplied by the BR-D85 editor. We found we could add layer after layer with no degradation in the original layer - all with only two edit decks.

At about $16,000 (for the Aladdin digital version) plus the cost of a reliable Pentium computer, the Pinnacle Aladdin makes a simple two machine JVC Digital-S edit suite into a front line media armory of competitive special effects. If you choose the SDI option, the Aladdin's digital version will bring you an all-digital edit suite for less than the cost of one Digital Beta deck!
(see sidebars for Pinnacle Aladdin and Compaq).

Wide Industry Support Growing

We believe this scenario is being repeated across the country. Various facilities, like Jeff Gould's, Action Video in Toms River, NJ, Jack Oswald's, Goal Productions in Pasadena, California, and Total Tape Publishing Co. in Tampa, Florida are all using Digital-S in NLE applications.

Gould is most enthusiastic about the new format. "We're using a DPS Perception system with the Toaster Flyer to edit. When we started inputting from Digital-S, our clients noticed the difference right away. It's given us a new sense of confidence that now we can go after bigger clients, and even, well, charge more money for our work. Digital-S has certainly improved our bottom line."

Oswald adds, "Here is a format that gives you real digital quality and it won't force you into bankruptcy."

Broadcasters are also taking note of Digital-S, adding the critical support that is necessary to launch a new format and make it a "de-facto" choice. KITV, in Honolulu, Hawaii, the nation's first all-digital TV station chose Digital-S for all acquisition and studio applications.

Ethnic American Broadcasting, which began in Fort Lee, NJ as a single channel Russian language radio simulcaster and is launching 20 multi-lingual channels into the Direct TV network in May, has decided to go totally in Digital-S. Director of Broadcast Engineering, Denis Roche tested many formats before deciding. "Our criteria was tape cost. After the initial purchase of equipment, it is the cost of videotape stock that continues and after a year or so, far outstrips the cost of the equipment. We examined DV and were not satisfied with the color resolution, although DVC-Pro was good for ENG, we didn't feel good about it's ability to copy generation after generation. We even tried Digital Beta, not because we could afford it, but as a benchmark by which to judge the other formats we were considering. We found Digital-S to be outstanding, in fact, indistinguishable from the Digital Beta."

Finally, Fox has bought into Digital-S bigtime. They've got them in New York at Fox NewsChannel and in L.A. at FoxSports and some of the decks have gone over 4,000 hours without a head change.

One of the overhead considerations of an edit suite is the hourly wear-and-tear cost. Considering that the average time for head replacement on analog or digital heads is about 1,000 hours, with a labor and materials cost of about $4,000 (say, for a Sony BVW series deck), the wear-and-tear cost would be $4 per hour. The Digital-S head changeover costs about $1,000. Average this out over a 4,000 hour lifespan and the wear-and-tear cost becomes inconsiderable.

Future Extensibility

In the future, Digital-S decks will act as economical hardware bridges to the DTV and HDTV demands that both consumers and clients will make in the next two years. Witness the recent Phillips thin-screen, 16 x 9 consumer TV commercials running nationally and the CEMA (Consumer Equipment Manufacturers Association) "DTV-Ready" logo being affixed to such sets. Although there are currently 18 different standards for DTV, all DTV-ready sets will be able to receive all 18 of them!

Those of us who have survived the Betamax-VHS and NTSC-PAL wars, have come to expect an eventual domination of a "mono-standard." This may never be the case with DTV. Many standards have unique properties which make them desirable and broadcasters will use each for specific purposes. For instance, one HTDV channel can carry four standard TV channels at one time. There will be times, even ten years from now, when that capability will be required, even for such a mundane use as a private remote security network. Some standards are better suited to feature films, while others will be used for news. As long as your set can receive the standards, broadcasters will use them, IF THEY ARE PROFITABLE.

Making a profit is easier when the production equipment is affordable. Those who discover, test and prevail using affordable equipment, will often succeed over those who opt for the high priced gear. The challenge is to find equipment that will amortize with one or two productions, not one or two years. For most producers, that means equipment costing under $20,000 per unit.

Even though NTSC 525-I will remain for some time as a viewing standard, more and more producers will be pressed to offer the higher realms of 480-I, 480-P, 490-30P, 720-P and 1080-I in the very near term. Digital-S can currently support 480-I, P and 30P, and JVC has recently announced the development of Digital-S at 100 megabits per second which will be the required data rate of 720 and 1080 standards.

Practical Experiences

So what is it like working with Digital-S and its assorted tools? We recently mounted a series of videos using the DY-700 Digital-S (one-piece) camera and edited on two Digital-S suites. The first suite was composed of a BR-D50 player, a BR-D85 editor, both equipped with the SDI (serial digital interface) option. These decks were controlled with a simple RM-G820U edit controller, running through a Pinnacle Aladdin, controlled by a Compaq 6000 Workstation. The second suite was JVC's newly released Timegate nonlinear editing system, tied to a BR-D85 editor.

Although we would have rather tested the new DY-90SW camera, which has switchable 16x9 capability, the DY-700, a good quality workhorse costing about $12,000 was superior to other cameras costing a lot more. The images were crisp, well saturated and of course, digital. While not a BVW-700, the results were close to the standard BVW-400 we've been using for the past two years and the output of the DY-29, JVC's current higher level product was equal to or better than the BVW-400.

Our cameraman, a veteran, noted that the camera, "had a lot of plastic." We took this to be a kind of criticism, since the camera body of the high end Sony cameras are mostly cast metal. Perhaps cast metal, which weighs more, has become established in users as some kind of "perceived value" of high priced cameras. Maybe the metal is a bit more rugged. Having given up combat videography, we'd prefer the lesser weight of plastic.

Certainly there are those critics (mainly those who've already invested in the higher cost gear) who will search for weaknesses in JVC's design. If it can be said that JVC is forced into a compromise when offering such stunning visual quality at such a low cost, we've come to the conclusion that wherever JVC is cutting the cost, it is merely cosmetic. JVC seems to understand very well that the quality of the image produced, is "where the rubber meets the road." Here is where JVC puts your cash.

Perhaps JVC gear takes a bit more care in handling, (the rubber knobs on our BR-D85 tended to come off while rack mounting the decks) and maybe you should baby it like you would a $70,000 BVW-700, but the picture quality far exceeds anything you would expect at twice the cost. And at twice the cost, you are still way less than the next most expensive 4:2:2 half-inch digital camera. And in the end, when you've paid for the equipment in months, not years, perhaps you'll get the idea that the gear is, well, expendable. A rental house could buy a half dozen DY-700's for one BVW-700; two or three DY-90's. You do the numbers.

Using a 1-hour lithium-ion battery and a 2-hour tape, the DY-700 came in a bit hefty, but the new DY-90 is only 15.4 pounds with the added benefit of four XLR digital audio tracks. One delight is the RCA monitor jacks, overcoming what has been one of our chief peeves with the high-priced gear that persists using 3.5mm mini-jacks when no acceptable headphones come with mini plugs.

Digital-S Editing

Once in the editing room, the quality of Digital-S became apparent. Simply put, Digital-S beats BetaSP by a Texas mile. Obviously, 4:2:2 digital is the future, so we decided to put the Digital-S format to a test against the most expensive form of field-produced 4:2:2, Digital Beta.

Taking a Digital Beta original tape, we made an SDI copy to Digital-S and then dubbed the Digital-S scene for 20 generations. While we are not engineers, we could perceive no difference between the playback of the original Digital Beta footage and the 20th generation Digital-S copy. This apparent level of transparency pays significant dividends on the pre-read decks.

Using our Pinnacle Aladdin 601 digital SEG, we created a scene with 30 small video frames all playing at one time. Using a horizontal wipe at the half-take position, we compared the background layer of the composition with the original footage from which the background was dubbed, the wipe line was invisible, indicating no perceptual loss from the first generation.

The Digital-S cassettes, now capable of recording up to 124 minutes in the field or studio, are a new metal particle tape stock, loaded into a beefier version of the VHS plastic case. While some will say these tapes are larger than their DVC counterparts, they are also a lot harder to lose, and we've lost a DVC tape in a pocketbook once. Furthermore, engineers agree, a 6 mm tape format will never be able to support 100 megabits per second, dooming the tiny cassettes once DTV becomes a reality.

We found that editing on the Digital-S decks a refreshing experience. Many people remark about the change in image sharpness when they convert to digital. In many cases, they are speaking about the Sony BVW-700. We found the experience on the Digital-S decks to be every bit as rewarding. Suddenly, our old composite monitors were looking flat and we had to have the JVC BM-H1900SU component monitor to really appreciate the quality. No doubt, the move to a digital monitor will be justified, the difference in picture is outrageously noticeable. Even my most complacent clients were remarking about the "sudden something" we had done to our videos that were making them look so good.

Executive Summary

JVC's Digital-S format is the ideal combination of quality and low cost. A true, 4:2:2 digital format with 50 megabits per second data rate on half-inch tape, Digital-S offers an extremely high quality image at about a third of the cost of similar equipment by any other competitor. While the superstructure may not be military spec, combat-ready, the operational and qualitative foundation of the equipment is adequate for all broadcast and industrial applications and will yield exceptional longevity. If you can't afford Digital Beta, Digital-S is the best choice. If you can afford Digital Beta, you still might want to go with Digital-S.