Media Servers

Avid Developing Tape-Based Archiving System

By Robert Lamm

I found it ironic that one of the new components in AVID's media server system is a tape-based archiving system. "Tape will not be going away," Matt Danilowicz, Avid's spokesperson, explained, "Tape and disk-based media will continue to coexist for a long, time."

The Nature of the Beast

Media servers are basically very large, centralized videodisk stations. They replace VTR’s in places like TV stations and production houses. With the proper computers and software hooked up, they can do things like nonlinear editing, automated program/commercial playback, network operations such as time-delayed broadcasting, etc. Because all the video footage is contralized, everyone in a facility can have access to it: You don’t need to carry cassettes around from room to room. This can streamline your traffic operations considerably: For example, a TV station could be recording a baseball game off satellite at one workstation, have someone editing that just-recorded footage at a second station, and scheduling the edited clip’s broadcast fom a third location all at once. Several TV stations have already been completely serverized, including one in Seattle run by long-time SMPTE/NE alum Brian Lay.

Physically, these servers consist of arrays of multi-gigabyte drives with the capability of recording/playing back several channels of video in real-time. But the design philosophies of the three systems discussed differ considerably:

Tektronix' server is basically a video device: It has video in/outs (digital component for now, analog composite and component due out soon), complete with genlock and RS-422 control ports to emulate VTR protocol, etc. Although it uses standard off-the-shelf computer hard drives and a custom-built EISA-486 motherboard, it also includes a Grass-Valley-built hardware router and switcher/DVE.

BTS' system is similar in concept, but leaves out the DVE and concentrates on plain vanilla record/playback. They’re putting a lot of effort into making the system make-good free: you can swap out any of the components, including the drives, while the system is running. I was surprised to learn that there’s enough redundancy in the recorded signal so that a broken drive’s data can be reconstructed from the sound drives that remain

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Avid's system is an SGI Challenge XL computer file server that connects their existing editing/playback products together. It’s 100% off-the-shelf components and doesn’t have any video capabilities whatsoever: All the interfacing and A/D conversion takes place at the workstations that hang off of it. These are hooked up to the server with high-bandwidth fiber-optic ATM cables so they can access the video data. And since disk storage is still a hell of a lot more expensive than tape, Avid is designing the aforementioned tape system for long-term archiving.

Making Servers Serve

It was interesting to hear how each company is developing the software that makes their hardware useful.

Avid has a head start here, their server is supported by the mature editing and airplay applications it was designed to connect. They're adding broadcast delay and databasing functions to this. Avid recently bought Basys and Softech and is planning to add some low-resolution desktop video into these companies’ newsroom computer products. Then journalists will be able to review and edit their footage right from their desktops. (It’s low-res because they don't hook into the fiber network.)

BTS is writing its own applications: So far they’ve got media recorder, cart machine, and broadcast time-delay modules written.

And Tektronix is forging third-party alliances with people like Odetics, Louth, and others, figuring that they’ll stick to the hardware side and let the application experts write the software.

Tough Questions

Image quality was an issue that came up constantly. Although all the systems seem to use similar MJPEG encoding, the off-disk data rates vary considerably. Tektronix was additionally claiming that their MJPEG encoding was superior, supposedly because they’re more expert at the algorithm. Avid gets a special prize for creative naming: Their server image quality, midway between AVR 26 and 27, has been christened 'AVR-70'. ('Cause it meets RS-170 timing specs- get it?) And poor Don Lenihan, the BTS product manager, manfully defended himself against audience member Wilson Chao, who argued that there really is no such thing as lossless compression. Wilson pointed out that even the 10-to-8 bit truncation that Digital Betacam does is visible and that there's got to be even more image loss with the additional 2:1 or more compression that the BTS system does. Don and Wilson finally agreed that ‘lossless’ compression is when the customer doesn’t notice it...

Unfortunately, Tektronix was the only company to bring product to the meeting, so it wasn’t possible to make comparisons. Howver, Tektronix’ picture looked pretty good to me. Special thanks to Tektronix for the hands-on demo, these are always especially appreciated!

The Bottom Line

The systems vary considerably in packaging details such as drive array configurations, number of video channels, recording capacities and extra features. The most basic Tektonix system with 2 hours or so of capacity starts at around $50,000. But the cost of the consumer computer drives they all use is coming down logarhythmically, so pricing is expected to drop steadily in the future.

A Glimpse of the Future

This whole dog-and-pony show was preceded by a very interesting presentation by our host. Todd Rodgers, Division Staff Analyst at TASC, gave us a quick tour of the Internet World-Wide Web.

Internet is a network that connects computer users over long distances. Just about anyone with a modem can hook up, and special high-bandwidth lines are available for people who want faster image retrieval and video capabilities. World Wide Web is a browsing protocol that’s especially easy to use and can handle images, video and hypertext.

Todd wandered around the Internet a bit, we checked out the CIA’s still-image database (Maps of South America) as well as the catalogs of a sneaker company and a telescope company. The applications go beyond hypertext and pretty pictures: One can hook up Coke machines to check if they’re getting low, track Federal Express packages, and check on science experiments in Antarctica without going there.

We also had a look at some video, I was very impressed: Todd was able to play close-to-VHS quality Volvo commercials live over the network. (ie. they weren’t downloaded prior to playback, they were being displayed as they were being transmitted from the data site.) This high-quality playback was made possible by an MPEG playback card in Todd's Windows PC. (A comparable Indeo-compressed AVI file, which doesn't require special playback hardware, played back much worse.) Todd predicted that most computer display cards would have MPEG playback chips as a standard feature before long.

Todd pointed out that the system still has a ways to go: Whereas most users can choose how much bandwidth their local in-house network has, the quality of the Internet links outside is unpredictable: Some have such low bandwidth or heavy usage that one’s personal data rate is substantially reduced. This slows the transmission of still images and cuts the resolution and frame rate of over-the-network video playback.

There's a company called LANCity that makes hardware to provide ethernet-type internet access on cable TV. But it’s limited to 10Mbit/sec, partially beacuse cable TV systems don’t have a lot of RF space for this service. If more than 8 people try to view video simultaneously, they can totally gridlock the system. Even just half that number will slow the data rate enough to reduce the image quality. At this point, Wilson Chao suggested that people who want full bandwith images should watch normal TV. And he pointed out that more than 8 people can watch at a time!

Nevertheless, the dream of point-point access with most of the population is beginning to come true: An estimated 22,000 ‘@’ organizations are connected, providing 22,000,000 people with e-mail, FTP and other Internet services. (Unfortunately, not all of them have video capability.) And usage is growing phenomenally: There has been a 600% increase in web traffic in the last 18 months.

One Internet issue that seemed to trouble many was viewer confidentiality. It turns out that every visit you make to a data site is recorded. Most people would probably merely use that to send you propaganda, but there’s always the possibility of more sinister uses. Todd pointed out that it’s the computer that’s registered, not the user. But one audience member thought that the CIA might be able to get around that limitation...

In Appreciation...

All of us at SMPTE/NE would like to offer our special thanks to all the speakers for their excellent presentations. Also, our heartfelt appreciation to Phil Ozek and TASC for hosting the meeting and providing delectatious munchies. And also a special appreciation to Wilson Chao for keeping everybody honest. It was a very enjoyable evening.

Robert Lamm is Manager at CYNC Corp., New England's most complete video/multimedia dealership. He can be rached at 617-277-4317, fax: 617-232-8748, cync@world.std.com.