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The Promise Of The All-Digital Video Chain

The explosion of consumer interest in plasma displays, HDTV, digital cable television, and Internet video is indisputable evidence that the proverbial digital video train has left the station. And Bruce Kaufmann, president of Professional Products, a Gaithersburg, MD-based AV design-build firm, is already onboard.

The explosion of consumer interest in plasma displays, HDTV, digital cable television, and Internet video is indisputable evidence that the proverbial digital video train has left the station. And Bruce Kaufmann, president of Professional Products, a Gaithersburg, MD-based AV design-build firm, is already onboard.

An early adopter of digital video technology, his systems integration firm is working toward all-digital video solutions on many of its installations, including the Georgetown University Medical Center in Washington, D.C. Its clinical skills system, featured on the front cover, is an excellent example of digital video acquisition and distribution over IP.

The Georgetown clinical skills center consists of 10 examination rooms that medical students use to practice and develop their clinical examination skills. Each of these rooms has two ceiling-mounted cameras and two ceiling-mounted microphones. All of the exam room video and audio feeds are sent to the control room (shown in the photo) where they're encoded into individual MPEG-4 video streams available on a LAN. Authorized users can decode and view these streams in real time on their computers. Professors and administrators are able to unobtrusively view and hear the students as they conduct examinations. Authorized observers can select any of the exam rooms and control the pan/tilt/zoom cameras from anywhere on the clinical skills LAN. Video from the exam rooms is distributed to the classrooms via IP.

But while early adopters like Kaufmann have clearly jumped on the digital bandwagon as entry prices have reached a palatable level, the pro AV industry and much of its commercial customer base, by comparison, has been a little more leery. In contrast, many are choosing to wait for the next train that might take them to the “all-digital” promised land more quickly, comfortably, and economically. While it's true some systems integrators are successfully moving more clients into state-of-the-art content creation and display devices capable of producing and handling digitally created content, the reality is that both camps still have one foot planted in the more familiar world of analog-based content creation, distribution, and display.

“I think there's a lot of interest in moving to all-digital audio/video systems for video, but there's still some resistance,” says Hagai Gefen, president of Gefen, a Woodland Hills, CA-based provider of HDTV integration, conversion, extension, and distribution solutions. “I've been a little surprised at how slow the process has been, but part of the problem is that many large pro AV customers have invested in custom analog technologies that they find difficult to justify throwing away.”

But one of the overarching reasons for the slow pace of adoption of pure digital video capabilities is the complexity of an all-digital video solution in the pro AV space, unlike in consumer applications. Sheer physical distances between video source and display, combined with the need to distribute content to multiple and different types of display devices has complicated the process of conversion to an all-digital video chain that would sidestep many of the challenges inherent in two-way digital/analog conversion processes that can diminish distribution efficiency and image quality.

At the same time, analog has its drawbacks. Distance is an enemy when it comes to the quality of the analog picture that reaches the display device, raising a barrier to effective transmission of analog video signals over distances common in pro AV applications. And, of course, analog can't compete with the resolution and quality of the higher-definition digital image that's quickly becoming the gold standard in video.

“Right now if you have a large AV system, and you need to mix and match analog and digital sources and displays at different resolutions, you may just choose analog because it's easier to put together,” Gefen says. “But once you discover how to mix and match digital displays and sources that adhere to the HDTV resolution formats, you'll realize the components have less maintenance, better quality, and less need for tweaking and aligning.

Audio as a DSP model

Digital technology has certainly done just that in the pro audio sphere. Digital signal processing (DSP) gear in the form of popular distribution matrix products like the Peavey MediaMatrix, Biamp Audia, and Symetrix Audio's SymNet (to name just a few) has vastly simplified the job of retrieving, processing, and distributing audio to amps and loudspeakers — all without missing a sonic quality beat. Via a computer interface, audio signals can be handled completely in the digital domain in a single box, bypassing the bulky analog components and connections commonly used to accomplish the task.

Given the growing popularity of DSP in the audio universe, coupled with the challenges that video distribution is facing in the digital realm, one question naturally arises. Is a configurable DSP solution in the cards for video? Or more specifically, can video, with its bandwidth requirements, multiple display formats and resolutions, and multiple types —from component to high-definition to computer-generated — be similarly massaged and managed in an all-digital environment?

Pierre Berthet, chief technical officer with Analog Way, a Paris-based analog image converter manufacturer, says he can envision a configurable DSP box solution, but the picture is still blurry.

“Yes, there's something like that in the industry's future, but it will take quite a long time to ingest these ‘ultra-compact' video technologies,” he says. “Even in the commercial pro audio field, the concept of all-in-one devices started slowly with products like MediaMatrix and then BSS' Audio Soundweb and Atlas Sound's Varizone. And like many new ideas, it could take some time to spread.”

One of the major challenges relates to video's bandwidth requirements combined with the rate at which the core processing capability of CPUs advances, Berthet says. Even with that capability roughly doubling every 18 months (according to so-called “Moore's Law”), Berthet says it could take 13 years for processing power to reach the speed needed to handle all of the processing of uncompressed stream SDI video. It could take slightly longer for processing power to reach speeds necessary to similarly handle higher bandwidth HD-SDI and computer UXGA.

“It gives an idea of the complexity of the task, even if we take into account the compression of algorithms that could make it happen slightly sooner,” he adds.

If and when such a solution arrives, Berthet says its evolution will be similar to that of the single DSP solution for audio. “The processing core and the remote/network areas will be in advance of the installed digital-link between the devices,” he says. “As for the input/output, it will progress from analog to digital, and in the pro AV world the progression will likely be core processing first, followed by control hardware, networking software, and, finally, the digital serial link.”

While it's tempting to speculate about more complete DSP solutions for video, some experts suggest taking a step back. Although DSP may do wonders for managing the distribution of audio, they remind us that audio is not video. Aside from the higher bandwidth and compression demands that video has by comparison, there may not be a real-world need for processing video as carefully as audio.

Rich Mavrogeanes, founder and president of VBrick Systems, a Wallingford, CT-based manufacturer of devices that make digital video networking possible, says end-users are much more demanding with audio than they are with video. Venue differences mandate the exact fine-tuning of audio that analog devices, and the DSP functions that mimic them, provide. The same variables simply aren't there for video.

“The human ear is much more sensitive to disturbances than is the human eye,” he says. “Audio has more stringent requirements than video in terms of how it's perceived at the end-user level.”

Defining audio quality

But Kaufmann says demand for the higher quality video that digital solutions can provide is growing among the commercial clients his company serves. Digital video's slow but steady emergence in the consumer space is helping to set a standard for image quality commercial users will feel compelled to conform to.

Public spaces in which digital signage is increasingly more visible is perhaps the clearest example of the need for high-quality video, Kaufmann says. “I believe the public is tuning into digital video because they're bombarded every day with digital content — whether it's video-on-demand via satellite, using home DVD players, watching streaming video, or editing photos on their home computers,” he says. “It's easier to get, and you can see it more places than you used to be able to. So as we advance in this area, digital video distribution may ultimately make more of an impact than digital audio.”

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