Technology Showcase: Videoconferencing Systems
Apr 1, 2008 12:00 PM, By Jay Ankeney
Long-predicted communications technology fulfills its potential.
Rarely has any technology revolution been so eagerly awaited and long predicted as the videoconferencing systems that are emerging into corporate, medical, and educational scenes today. As long ago as Fritz Lang's 1927 silent classic Metropolis, the corporate executives of the Upper World conversed through video screens — even though the reality of Flapperera television was still in its fuzzy, gray infancy. When video communications did become feasible in the '30s and '40s, the concept of closed-video communications was hatched first as closed-circuit TV (CCTV). The earliest recorded CCTV installation was designed by German engineer Walter Bruch in 1942 using a 441-line system and installed by Siemens AG at Test Stand VII in Peenemünde to monitor the launch of V-2 missiles. Primitive by today's standards, it was considered high definition compared to the Baird or Farnsworth televideo systems of the time. The concept would wait more than half a century to become practical.
The paradigm switch from one-way watching to two-way AV interaction began to take shape at the 1964 New York World's Fair, when AT&T introduced its Picturephone in a desktop cabinet. By the 1967 Montreal Expo, it had become the Videophone, equipped with a Plumbicon camera and a small CRT receiving 200 scan lines over a 1MHz bandwidth. By 1970, Picturephone booths were set up in Grand Central Station and in the Pittsburgh offices of Westinghouse, along with other forward-looking companies. But the technology proved more Buck Rogers than Daddy Warbucks, and the service died by 1974. A Sept. 6, 2001, report on CNN said the Picturephone service only had 500 subscribers at its peak.
There have been several other attempts to find a market for closed-AV communication systems, but for most, the verdict was that a sour apple is worse than no apple at all. By the 1980s, the advent of circuit-switched ISDN lines could ensure a minimum bit rate of 128kbps, and brave firms such as PictureTel (later purchased by Polycom) used highly proprietary equipment to market the idea, but it experienced limited success. By the 1990s, the rise of Internet Protocol (IP) brought with it free services such as NetMeeting, MSN Messenger, Yahoo Messenger, and Skype. Although the public enjoyed the novelty, the quality of these services was so low that corporations could not rely on that form of videoconferencing — which was by then referred to most often as videoconferencing or video teleconferencing (VTC) — as a serious business tool.
But in the last few years, a perfect storm of converging technologies has brought videoconferencing onto the main stage of corporate communications. The popularity of high-definition consumer televisions brought the cost of HD displays to an affordable level for widespread corporate installation, but the label of “high definition” that is stuck onto many high-end VTC systems needs to be taken with a grain of salt. A large number of them have adopted the relatively bandwidth-efficient 720p format (16:9 widescreen with 1280×720 resolution), but they are sending it out with only 30 fields per second (720p/30) — or sometimes even less. That would not qualify as high definition in the broadcast sense, so the “/30” or “/60” indication of the field rate will be included here when it is available. On the other hand, there is a strong movement by several companies toward providing full-1080p image density, which is more image density than even the best network broadcaster can pump out today.
The videoconferencing experience has rapidly improved thanks to recent developments, such as the increased bandwidth of both the Internet and private networks to provide the transportation throughput, improved compression from codecs such as H.254, and most importantly, the fact that the International Telecommunications Union (ITU) has given the industry three umbrellas of standards for videoconferencing: H.320 for public switched telephone networks (PSTN), H.323 for transporting packet-based multimedia applications over LANs, and H.324 standard for transmission over audio telephony networks or POTS (plain old telephone service). With the advent of standards, not only have videoconferencing systems become more reliable, but thanks to bridging technologies, VTC systems from different manufacturers are even beginning to talk to one another.
Another growing initiative called “Session Initiation Protocol (SIP),” designed by Henning Schulzrinne and Mark Handley, has helped this much desired goal. SIP offers the promise of a common protocol for creating, modifying, and terminating voice- or video-call sessions with one or multiple participants. Thanks to these developments, the top videoconferencing companies have even developed a new buzz word — telepresence — to describe the highest-end VTC systems, but few can agree on exactly what it means.
The basic concept behind telepresence seems to be an experience that is so real, it makes the participants feel as though they are all in the same room. This depends on a combination of high-definition video representing life-sized images, multichannel sound, a controlled environment, managed connectivity, and directed perspectives from the “local end” (you) and “far end” (them). This includes a concept of gaze control to make the sight line of everyone's image appear as if they were speaking directly to other participants instead of into the eye of a camera.
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