Polycom Offers Videoconferencing On A Budget
Posted by
Phil Hippensteel
December 02, 2009
Of all the collaboration methods available to business workers, it's hard to beat face-to-face interaction. Three products from Polycom aim to put videoconferencing capabilities within the reach of small and medium-size businesses, and with video calls that start at 256Kbps, most networks should be able to easily handle the additional traffic.
We looked at three systems all designed for IP networks. The HDX 6000 is a high-definition conference-room style video conferencing system. The QDX 6000 is its standard counterpart. We also looked at a product for desktop videoconferencing, the Converged Management Application (CMA) Server and its client component. CMA clients can conference with both the HDX and QDX 6000.
Both the HDX and QDX 6000 systems come with their own video cameras, both of which have excellent resolution and depth of field. The CMA client runs on a PC, and cameras aren't included. If you've got users who'll spend a lot of time on video calls, we recommend spending extra for high-quality cameras, which make considerable difference in the quality of both the video and audio output. USB headsets will also take full advantage of the audio.
We set up the HDX 6000 ourselves. It took less than an hour to unpack, configure the systems and begin a conference. Polycom provides an excellent online video to help with set up, as well as a quick-start guide packed in the shipping container. Configuring the network address was easy with intuitive administration screens. All three systems automatically try both H.323 and SIP to set up a call. If a firewall sits between the endpoints, both will use the H.460 standard on an H.323 call to traverse the firewall.
We tested each system at our lab with excellent results. We used a PacketStorm network emulator to introduce network loss ranging from 0.5 to 3 percent with each system. We wanted to see how Polycom's Loss Packet Recovery (LPR) would work. In every case, the system detected the lost data and used forward error correction to calculate a good quality video output signal. When scenes had little motion, the video was exceptional. Even when the camera recorded some motion, the output was better than would be expected.
The additional bits transmitted to provide the error correction increased bandwidth use, but we never exceeded the nominal rate of the call. At the highest levels of loss, delay increased due to the increased size of the jitter buffer. However, it never rose to an unacceptable level.
While the systems handled packet loss well, they all had difficulty with excessive jitter. We added 2 ms., 10 ms. and 20 ms. of jitter. The lower levels presented no problem. However, at 20 ms, both sound and video deteriorated significantly. While the latter level would be very unusual, it could show up on a corporate network with bursty data applications. We recommend measuring the level of jitter on your network before you deploy a video communications product.
With the CMA system, we found little difference between calls made on our corporate network and those made over the Internet, except for a moderate difference in delay.Note that the CMA client lets the user indicate the type of network connection to be used. You may want to help users get this right, because their choice will adjust the jitter buffer and set LPR, and the quality drops with the wrong setting.
The QDX supports 4CIF, a video conferencing standard that is very close to standard-definition television. The HDX supports a range of resolutions that include 4CIF using a little as 256Kbps. However, the HDX also will support high definition 720p at 30 frames/sec starting at 832Kbs. Polycom plans support for 1080p30 later this year. Both systems support high quality audio at 22 khz. At this level, speech is crisp, with little confusion of the letters f and s or p and t, for example.
These systems offer a strong combination of quality and value, making video communication possible within the enterprise and between business partners for a moderate investment. The QDX 6000 list for $3,999 and the HDX 6000 is $5,999. Pricing for CMA ranges from $15,000 for 100 client licenses to $284,000 for 5,000 client licenses.
Phil Hippensteel is an assistant professor of information systems at Penn State University and an industry consultant.
