Video conferencing is a video-communications session among three or more geographically separated people. This form of conferencing started with room systems, in which groups meet in a room with a wide-angle camera and large monitors to conference with other groups at remote locations. Federal, state and local governments are making major investments in group video conferencing for distance learning and telemedicine.
Although the earliest video conferencing was done with traditional analog TV and satellites, in-house room systems became popular in the early 1980s after Compression Labs (now part of VTEL) pioneered digitized video systems that were highly compressed and could be transmitted over leased lines and switched digital facilities available from telephone companies. Companies such as PictureTel and VTEL produce group systems.
WAN, LAN and Standard Telephony
The standard for video conferencing over a wide area network (WAN) is H.320, which defines the communications handshaking and the compression algorithm for reducing the digital video into a smaller bandwidth. H.320 runs over ISDN, Switched 56 and T1 lines. Multiple ISDN lines can be coupled, providing bandwidth in multiples of 64 kilobits/second.
Desktop video conferencing over local area networks (LANs) and through standard telephone service are also widely available. Although many proprietary systems were used for first-generation systems, the H.323 (LAN) and H.324 (regular telephony) standards have made different video conferencing systems compatible.
Desktop video conferencing systems come with a camera and one or two boards for video capture, video compression and ISDN hookup. Some systems are dedicated to video conferencing, while others can be used for other transmission and video purposes. WAN-based systems (ISDN) generally run around $1,200 to $2,500 per workstation. LAN-based systems, which attach to an Ethernet instead of an ISDN line, run from $700 to $2,000. Standard-telephony systems are usually a lot cheaper.
As with everything else, the Internet has affected this field tremendously, causing all video conferencing vendors to introduce H.323-based products using the IP protocol for their LAN offerings. While the global Internet cannot currently guarantee the quality of service required for realtime interaction, video conferencing over an in-house, IP-based intranet is much more viable, since most networks have been or are being upgraded to 100Mbps Fast Ethernet with 1000Mbps Gigabit Ethernet backbones coming on strong.
At 768Kbps, digital video conferencing is like analog TV. At 384Kbps, it's more than usable, and even quite respectable at 128Kbps. It takes 24 frames per second (fps) to make the video frames look fluid and fool the eye into believing the motion is continuous. Thus, it's always a tradeoff between the video window size you want on screen and the available network capacity. The bottom line when there is not enough bandwidth is fewer fps, and the more we move down from the ideal 24 fps, the jerkier the motion.
Companies such as Datapoint, with its MINX system, forgo the digital domain and provide full-motion video via an independent analog video network. MINX still uses the LAN for data conferencing, but, since the video is not dependent on the LAN, it will still work if the LAN goes down.
A concomitant part of video conferencing is data conferencing, which allows data and documents to be shared by multiple participants. Whiteboards, application sharing and application viewing run on the International Telecommunications Union's T.120 standard. These data-collaboration tools can be used with audio only and even on the Internet, because realtime interaction is not critical. If you paste an image into a whiteboard, and it takes a couple of seconds to register on somebody else's screen, it is not at all as annoying as the delays in audio or video frames.
A whiteboard is the electronic equivalent of a chalkboard. Participants at different locations can simultaneously write and draw on an on-screen notepad that is viewed by everyone. A document, drawing or even the screen shot of an application can also be pasted into the whiteboard and annotated by conference members. Application sharing is like remote-control software for multiple users, in which participants can all interactively work in an application running on one user's machine. Application viewing is similar, but although everybody can see the program running, only one can edit the documents involved.
Point-to-point and Multipoint
A point-to-point conference between two people is relatively simple. In fact, that's not really conferencing. It's videophoning. You need at least three locations for true video conferencing, which has several considerations. For example, does everybody hear and see everybody? There's not that much real estate on a large monitor, let alone a PC screen, to show large numbers of people if they are all in different locations. Does the video follow the person speaking, or is the entire session moderated by one person who is entirely in control of who sees what?
A multipoint conference is managed by a multipoint control unit (MCU), a specialized device or software in a server that coordinates all this. The MCU joins the lines and switches the video according to the method required. Multipoint conferences are also achieved by connecting to a conferencing network service from a common carrier.
You Already Have It
Much to the chagrin of everybody else, notably its competitors, Microsoft is giving you multiuser whiteboarding, application sharing, file transfer and text-based chat, along with point-to-point audio and video, and it's all free in the form of NetMeeting. If you have Windows 95, you can download it from Microsoft's Web site. If you use Windows 98, you already have NetMeeting installed. All you have to do is plug a $99 QuickCam camera into the parallel port or USB port of your PC, and you're off and running. Add White Pine's MeetingPoint to your server, and you can multipoint video conference your NetMeeting users along with any other H.323-compliant video conferencing system, including Intel's ProShare and Internet VideoPhone, PictureTel's LiveLan and CU-SeeMe.
The Grandma Connection
Although videophones were expected to be in widespread use long before now, the lack of bandwidth in the local loop, between home/office and telephone company, and the lack of telecommunications imagination have prevented it. As ISDN, cable modems, satellite dishes and digital subscriber lines become mainstream and economical, the world of video phoning and video conferencing will eventually emerge. In the meantime, if you want to see your beloved kin who live hundreds of miles away more regularly, you can either turn to the Internet or to stand-alone videophones.
It has long been proven that in a video session, it's really the audio that's more important. If you try to have an ongoing videophone relationship with your grandchild over the Internet, it may be dissapointing. The Internet will fracture the speech just enough to make it frustrating, especially for a youngster. You really need to talk via phone and watch on screen, or you can use consumer-oriented devices such as 8x8's ViaTV units. They come in models that hook up to your TV or stand alone with a built-in camera and 4-inch screen. They're not a universal solution, because you need one at each end. But considering that they generally connect at 26Kbps, the ViaTVs work amazingly well, as long as you don't move around too much, which causes your image to pixelate (get blocky). After all, 8x8 is squeezing video over a line designed for a 3000Hz voice conversation. Grandma will be thrilled, and it's a nice way to keep in touch.
Waiting for the Call
The explosion of video conferencing always seemed to be right around the corner, but that corner has been farther down the road than many expected. In 1998, it was only a billion-dollar industry, with PictureTel owning about half of it. However, in time, it is still expected to be huge. When new carriers such as Qwest and Level 3 become fully operational ... when cable modems and DSL become ubiquitous ... when Fast Ethernet becomes entry-level networking ... and when the Internet supports true quality of service ... video phoning and video conferencing will finally become a major part of everybody's IT budget, and every family's personal budget as well.
courtesy of PictureTel Corp
and VTEL Corp.
Video Window or Full Screen?
It's always a tradeoff. The more pixels in the video image, the more network bandwidth required for the transmission.
A smaller video window (top) allows more conference members to be viewed at the same time.
courtesy of VTEL Corp.
The room system is where video conferencing got its start. It is still commonly used for small and large business groups. Most systems use ISDN lines and the H.320 standard.
courtesy of VTEL Corp.
Video conferencing is a natural for classroom training, allowing instructors to teach an audience that would otherwise be impossible to reach. This room system provides digital video conferencing to remote sites around the country.
The ability of conference participants at remote locations to view and interact with the same data or application may be as important as seeing the participants.
Whiteboarding offers the most basic of these capabilities. In the example shown above, a drawing was pasted into a Microsoft NetMeeting whiteboard. Using a red pen, a
of 8x8 Inc.
particular area of interest was circled for participants at all locations to see.
The ViaTV Videophone
8x8 makes self-contained videophones such as this, which is used with a standard phone. Another model uses the TV for display. Each side can use either type, and both models are just about as easy to use as the telephone. As long as people don't move around a lot, causing the image to pixelate, the quality is downright respectable, considering that video is being squeezed over a line designed for voice.
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