by A.B. Covell  Designing a Videoconferencing Solution Characteristics Of A Successful Videoconference Solution The goal of any videoconferencing system is to provide an illusion -- so that people look and feel like they are all sharing the same space, with each location an extension of the other sites that is seen through the "window" of the monitor or other display device being used. Success is attained when technology is no longer noticeable and fades into the background and videoconference participants are able to focus on their conversation and their work. The Number 1 factor affecting the ability of a system to achieve the illusion is the perceived quality of video and audio, and this is one of the primary factors to consider when evaluating any videoconferencing technology. This means rich, full-duplex audio with no echo or noticeable delays. Video quality is a function of frame rate, pixel resolution and monitor size. Video should be clear with rich colors, and it should be free of jerky movement, ghosting, freeze frames, or other visual anomalies. Digitizing audio and video results in large amounts of data, which is extremely expensive to transmit across public or private networks. As a result, videoconferencing systems use some sort of lossy compression for digital audio and video. The ability of video and audio compression engines (called codecs) to deliver good quality audio and video, given network bandwidth constraints, is partly responsible for the resulting perception of quality. Another important factor determining the perceived video/audio quality is the network itself -- unreliable or slow connections can destroy video and audio quality, no matter how good the monitor, or the speakers, or the codec, though some codecs will respond to these conditions better than others. The quality issue is directly related to another prominent feature of alternative videoconference systems, which is price. This relationship can be stated plainly: The more you pay, the better the quality you'll see and hear. Videoconference systems at the low end include inexpensive desktop computer and plain old telephone system (POTS)-based systems that cost a few hundred dollars and offer postage stamp, jerky video and half-duplex audio. At the other extreme is the executive room system costing hundreds of thousands of dollars -- it has multiple cameras, microphones and monitors and offers near-broadcast quality video and audio across the WAN or the pubic switched network. Another key characteristic is flexibility. The ability to interoperate with videoconference users on other systems, the ability to use the public switched network, the ease with which a system can service large numbers of participants, and the ability to share applications and documents as well as video and audio, are all considerations that determine the overall flexibility and functionality of systems you'll be evaluating. D irectly related to the flexibility issue, is adherence to standards. The International Telecommunications Union (ITU) has been very active in defining standards for videoconferencing over circuit switched digital networks, POTS, and packet networks (LAN/intranet/Internet). The ITU standards define compression algorithms for video and audio, document and applications sharing, bandwidth aggregation and multipoint conference control. The standards enable interoperability, thereby ensuring a degree of flexibility that is an important consideration at all videoconference system price points. A summary of the relevant ITU standards appears at the end of this section. Videoconference network requirements and their impact on existing and planned network applications is the other key characteristic on which you'll need to focus. Videoconferencing systems can consume large amounts of bandwidth, so it's critical to plan accordingly, whether it's bandwidth on your enterprise LAN and WAN or bandwidth obtained on demand from the public switched network. For more on this, read the Network Considerations section, below. Designing a Videoconferencing Solution Typical Videoconferencing Applications Characteristics Of A Successful Videoconference Solution Summary of ITU Videoconferencing Standards Videoconference System Alternatives Network Considerations Mix and Match Sample Scenarios Putting It All Together Videoconferencing Web Resources Print This Page E-mail this URL