ViDe Videoconferencing Cookbook
What is Videoconferencing?
Videoconferencing in its most basic form is the transmission of
synchronized image (video) and speech (audio) back and forth between two
or more physically separate locations, simulating an exchange as if the
participants were in the same physical conversation. This is accomplished
through the use of cameras (to capture and send video from your local endpoint),
video displays (to display video received from remote endpoints), microphones
(to capture and send audio from your local endpoint), and speakers (to
play audio received from remote endpoints). Although there are many factors
that serve to modify or increase the complexity of this basic definition,
several of which are discussed in this cookbook, it is useful to keep the
concept simple in the beginning when deciding why or how you may be able
to use videoconferencing for yourself or your organization.
In understanding the role that videoconferencing could play, consider
two general situations: 1) those where you are already able to communicate
with someone who is not physically nearby, but you wish that communication
could be richer, and 2) those where you wish to access or communicate to
a location that may or may not be nearby but access to it is limited by situational
or physical constraints.
Distance education often comes to mind when considering the first
situation. However, it is worth reminding ourselves that videoconferencing
can also be used to connect people with remote data, events, places and
objects in real-time fashion. Several other types of communications can
also be enhanced or extended. These include organizational and cross-organizational
meetings, counseling, foreign language and cultural exchanges, and telecommuting.
Communication is already occurring in each of these applications, but could
be made more compelling, more effective, or less expensive through the
use of videoconferencing. (Imagine a telephone call where you can see the
speaker, or a television through which you can talk.)
For the second situation, the introduction of videoconferencing
has enabled communication to restricted areas such as clean rooms, nuclear
facilities, operating rooms, and the space shuttle. Videoconferencing enables
us to teach students about the science and specialized equipment at hard
to reach places such as remote laboratories, installations near volcanoes,
remote lighthouses, telescopes, and microscopes. It has been used to observe
wildlife in their natural habitat, to establish interactive surveillance
and security and, combined with micro-instrumentation, to observe inside
the human body. This side of videoconferencing may not come to mind as
readily as the enhancement of simple communication but it can be quite
powerful. Simply imagine situations where you might like to be a "fly
on the wall" with the ability to interact if desired.
To imagine even further, consider that videoconferencing can be point-to-point
(between two endpoints), or multi-point (combining two or more endpoints
into the same "conversation"). When you begin to combine diverse
endpoints into one setting where audio and video from each can be shared
in real-time, whole new levels of interaction are enabled and entirely
new ideas for communication can result.
Once you determine that videoconferencing is for you, you need to
be aware that there are a variety of technologies that provide this functionality
and, overall, it is not at the point of being a "plug-and-play" technology.
Videoconferencing actually began over a decade ago with the introduction
of expensive group conferencing systems designed to send and receive compressed
audio and video over network connections that could guarantee a dedicated
rate of transmission and predictable service (i.e., point-to-point T1 or
fractional T1 communication links, switched connections using ISDN, or
ATM). Standards surrounding how the audio and video would be compressed,
how the endpoints would communicate with each other (i.e., initiating/terminating
calls, negotiating audio/video compatibility, indicating error conditions
during a call), and how the video streams would travel over the network
eventually evolved but systems were not fully interoperable at the start.
Arguably the most popular and extensible early compressed videoconferencing
was enabled via the ITU (International Telecommunications Union) standard
called H.320 (videoconferencing over dedicated circuits - ISDN.)
However, even with H.320, videoconferencing remained largely
restricted to a) those that could afford the technology, network connections
and meeting rooms, or b) those who were able to travel to a videoconference-enabled meeting location.
As time has gone on, the above restrictions have lessened. The technology
for conducting videoconferencing has become less expensive, more flexible,
and now includes options for desktop videoconferencing as well as group
videoconferencing. More ubiquitous network types, particularly TCP/IP as
used on the Internet, are commonly used to provide less expensive and more
flexible connections. In conjunction with this, standards have emerged
for supporting audio/videoconferencing over IP. The H.323 standard was
first approved by the ITU in 1996, has evolved through several versions
then and is
implemented in a wide variety of commercially available products. The IETF
SIP Working Group is working to move the SIP protocol from proposed to
draft standard and SIP-based videoconferencing tools are on the market
today. Products in each of these standards are the primary focus of this
cookbook today, however, information regarding other standards and means
for videoconferencing is also included. In addition, the cookbook touches
on many other factors required for a thorough understanding of videoconferencing.
These include the importance of standards in general; videoconferencing
needs assessment; application possibilities; basic equipment selection
and use; advanced components and services; and new developments. It is
both hoped and anticipated that the cookbook will help you to move from
imagining what you might do with videoconferencing to a successful and
effective videoconferencing deployment.