th properly configured systems, because IP videoconferencing relies on a medley of hardware, software, and networking technologies, it has a ways to go before it is as easy as picking up a telephone.
The International Telecommunications Union (ITU) H.323 specification is a vendor-independent standard that defines how audiovisual conferencing application data can be transmitted over an open network using standard transport protocols like TCP/IP. Two of the earliest products that adhere to or are on the verge of adhering to this standard for audiovisual conferencing are White Pine Software's CU-SeeMe version 3.0 and Microsoft's NetMeeting version 2.0. Collaborative tools, which make videoconferencing
with these new clients even more useful, include electronic whiteboards to provide blank drawing space that can be used by all participants; shared applications to allow all participants to view the same application window while one participant at a time manipulates it; file transfer; and chat.
Standards-based
IP collaborative
software is still fairly new technology, and it requires a platform of a well-equipped PC configured for IP connectivity. But there are many other players besides White Pine and Microsoft in or near this market, with more videoconferencing products that were still in the pipeline when we compared CU-SeeMe and NetMeeting (
see the table
).
Getting It Together
Interoperability is the name of the game, especially when you're playing with IP. No matter how good a proprietary videoconferencing solution is, if it can't play nicely with the other videoconferencing solutions, it's not going to be as useful to you. Despite the early
implementers' claims of adherence to H.323, I couldn't interoperate CU-SeeMe with NetMeeting because CU-SeeMe's H.323 client-to-client interoperability capability would not be available until long after I finished testing. This capability will be enabled through White Pine's MeetingPoint videoconferencing server product (an upcoming BYTE will feature an Eval on this product). NetMeeting happily interacted with other video clients, but CU-SeeMe requires MeetingPoint to support multipoint, multiwindow videoconferencing with other H.323-compliant clients. White Pine reported that CU-SeeMe clients will get direct compatibility without the server in an upcoming release due early next year.
Another stumbling block for many users will be taming the configuration beast. You'll need to put together video inputs, audio inputs and outputs, and proper IP networking software and configuration, as well as the videoconferencing software itself. Even when it all comes in a single package, it doesn't always work right
out of the box. CU-SeeMe and NetMeeting both include installation wizards, and both support any video-capture board that supports the Video for Windows standard, but software setup may still require fine tuning, particularly when dealing with firewalls and managing bandwidth consumption on internal LAN connections.
So Many Standards
Interoperability issues go beyond compatibility among clients: Videoconferencing is a complex application that has to interoperate with other network pieces, too. The H.323 standard for multipoint audiovisual communication complicates matters for firewalls because it uses two separate Transmission Control Protocol (TCP) connections as well as User Datagram Protocol (UDP) datagrams to set up and maintain a single connection. (TCP is a virtual circuit transport protocol; UDP is a connectionless transport protocol.) T.120, the standard for multipoint document conferencing and data sharing, requires only a single TCP circuit, unlike H.323, so data conferences do not pos
e the same problems to a firewall as do audio and video communications. (For more on standards, see the sidebar "Conferencing Standards".) Both NetMeeting and CU-SeeMe can be configured to work through firewalls, but doing so is not trivial. Unless the firewall explicitly allows H.323 videoconferencing, the administrator must manually open the TCP and UDP ports used for conferencing.
Performance Problems
Latency, the delay in receiving a signal after it has been sent, can really hammer bandwidth-hungry apps like live video: A transient delay of more than a fraction of a second can seriously disrupt reception. Microsoft NetMeeting has an automatic tuning mechanism that makes audio quality easy to adjust to compensate for bandwidth variations. CU-SeeMe uses forward error correction to compensate for packet loss on the Internet, and it uses interleaving to cut down on the actual data losses when packets are dropped.
Because audio and video streams are so bandwidth-intensive, videoconferenci
ng products must compress data on one end, send it over the network, and decompress it on the other end. This process of compression and decompression reduces the quality of the original, manifesting itself in many ways: as dropouts, static-plagued audio, or blotchy, pixelated video. Codecs are the software that compress and decompress this data, and selecting one codec over another involves issues that include quality versus performance trade-offs, the amount of bandwidth that is available, and the need for interoperability.
These products
also use different audio codecs to allocate a certain amount of the data stream for audio transmissions, for different bandwidths. This helps keep audio quality up to snuff without adversely affecting video quality.
Anyone who has used a cheap speakerphone knows that only one party can speak at a time, and when someone at one end of the connection is speaking, the people at the other end can only listen; this is half-duplex communication.
Hands-free, full-duplex conferencing, provided by both CU-SeeMe and NetMeeting, allows different participants to hear and talk at the same time, though at the cost of additional bandwidth.
An approach to managing the bandwidth beast is to use so-called "gatekeeper" products, which let system administrators monitor video and audio streams. Unlike gateways that route H.323 traffic, gatekeepers monitor and limit network bandwidth and let administrators restrict the bandwidth used by streaming video and audio applications.
Many other variables can affect performance during videoconferencing sessions. For example, connecting the camera to a video-capture board is much more efficient with system resources than linking through the parallel port. I found that mixing LAN and dial-up links in the same conference bogged down the test system.
Desperately Seeking Someone
Users can register their contact information with a location server, like the one from Four11, or with Microsoft's own Interne
t Locator Server (ILS). A directory based on Lightweight Directory Access Protocol (LDAP), ILS will eventually be integrated into Microsoft's Active Directory Services. Client software notifies the server of things like IP address changes each time the user connects. You can connect directly to videoconference participants as long as you have an IP address for them; using a directory service is not always necessary and can be time-consuming. Some of the directories must deliver their entire database every time you make a query, though eventually they will support more efficient search methods.
How to Decide?
We tested these products for ease of learning, ease of use, sound quality, and range of features. Video quality was measured subjectively by our NSTL testers, and the results were included as part of each program's ease of learning and use scores. The tests designed to rate ease of learning and ease of use assumed the products would be used to run a meeting between geographically dispersed
participants.
White Pine CU-SeeMe
CU-SeeMe is the grandaddy of video over IP. White Pine was first to market with IP-based group videoconferencing, though the version we tested required White Pine's upcoming MeetingPoint server-based reflector software to interoperate with other vendors' clients. The only program we've tested that displays video of more than two participants simultaneously, CU-SeeMe allows up to 12 video windows in a virtual conference room. You can have additional floating windows on top of that, although that many open video windows would tear through lots of system resources.
CU-SeeMe controls allow individuals to limit send and receive rates, but this must be done on a client-by-client basis. MeetingPoint will let clients with lower bandwidth participate in conferences with clients that have much higher bandwidth, permitting everyone to get the best possible quality based on their own bandwidth.
CU-SeeMe's Rolodex-style contact interface is a straightforward dir
ectory mechanism, though its display of splashy animation prior to each connection makes it cumbersome during routine use. Directory service is provided through Four11, and White Pine adds support for the Versit vCard standard for transferring electronic business card information. The Four11 service and vCard make for more helpful directory entries. Direct support for X.500 directories through LDAP is planned for the next release.
Integrated chat, also available with NetMeeting, helps a lot during those times when low bandwidth or a spotty network connection limits transmission of usable audio or video. Chat is well-integrated into the CU-SeeMe interface. This mode includes support for macros to create keyboard shortcuts for longer character strings, filters to screen out the ranting of specific participants, and a private facility to set up one-on-one conversations -- a capability that extends to private audio conversations, too. CU-SeeMe uses T.120 to transport data for whiteboarding and file transfer
, as does NetMeeting.
Microsoft NetMeeting
With Microsoft NetMeeting, no matter how many participants there are in a meeting, only two video windows can be displayed at the same time. Audio and video are point-to- point, unless you're using an H.323 conferencing server; application sharing, whiteboard, and chat are all multipoint without an extra server; for audio and video, you can switch among members of a conference without a server. Thus, participants must request the use of the video window when they want to be seen by the other participants.
NetMeeting's whiteboard won't yet interoperate with CU-SeeMe's White PineBoard because White Pine uses the T.126 protocol for whiteboarding while Microsoft devised its own standard. The NetMeeting whiteboard application runs on top of the T.120 services. A Microsoft spokesperson said the company developed the proprietary protocol before the T.126 standard was set. Although a T.120 connection can be made, the two applications cannot share any whi
teboard data.
Microsoft NetMeeting uses the T.128 application-sharing protocol to allow one user to share access to the document through the conference. NetMeeting's application sharing allows only one person at a time to have control over the document, but anyone participating who gets control of it can make changes to it.
Microsoft NetMeeting combines ease of use with lots of functions. Its unique ability to allow remote-control collaboration and video, audio, and chat channels make it well suited for technical-support applications.
Something for Everyone
Videoconferencing and data conferencing are developing technologies. Neither White Pine nor Microsoft has fully addressed all the needs of a routine project-status meeting between multiple, geographically dispersed participants, running over the Internet. But both products offer something the other lacks. Microsoft NetMeeting's remote-control application sharing suggests implementing it as a tool for remotely providing technical
support -- a help desk staff can take control of a user's computer. Unlike dedicated remote-control products of the past, the real-time communications mode can allow the user to explain the problem as the help desk staffer is working on the problem. Still, sound and video quality are essential in this scenario, too, raising the bandwidth and quality issues.
Alternatively, the popularity of chat rooms on on-line services suggests that a product like CU-SeeMe that offers multipoint video, audio, and chat will benefit from the user base of the chat culture. CU-SeeMe is designed to accommodate all three media in an interface that is familiar to users of chat sessions. If you're looking for broadcast-quality interaction over the Net, it doesn't exist yet. But if you've ever wanted to hear and see the colleague you've traded e-mail with, or the person you've talked with in a chat room, CU-SeeMe is just what you need.
Where to Find
CU-SeeMe 3.
0......................$99 list; $69 via Web site
(Windows 95, NT 4.0; Mac version in beta)
White Pine Software
Nashua, NH
Phone: 603-886-9050
Fax: 603-886-9051
Internet:
http://www.cu-seeme.com
Enter 1022 on Inquiry Card.
See and Be Seen Over IP
