All Categories :
Intranets
Chapter 25
How Intranet Videoconferencing
Software Works
CONTENTS
Intranets are all about communication. And there is often no better
way to communicate than in face-to-face encounters. However, intranets
are also about communication outside of physical boundaries like
buildings, companies, states, and countries. Often, of course,
face-to-face meetings are not practical, due to time limits or
budget constraints. In a corporation with branch offices, for
example, it can be very expensive and a waste of resources to
fly people from all over the country to a single location for
a one-hour meeting. With intranet videoconferencing software,
however, people can hold face-to-face meetings even though they
are located on the other side of the continent from each other.
It allows people to see each other and talk to each other while
seated at their computers.
Videoconferencing requires a few simple hardware components: a
video camera, a microphone, and a sound card for each participating
computer. The cost of this hardware has dropped dramatically so
that it's quite affordable-and most new computers now come equipped
for sound.
There are many different software programs available for videoconferencing
on intranets. Microsoft and Netscape, among others, are pushing
videoconferencing systems. The longest-standing videoconferencing
system on the Internet-CU-See-Me-also has intranet-based videoconferencing.
It has been around longer than any other IP-based videoconferencing
product, and that's what we'll look at in this chapter.
CU-See-Me videoconferencing works on a client/server model, like
many other intranet applications. The CU-See-Me client runs on
a local computer, and it can run on many different kinds, including
PCs and Macs. When someone wants to join a videoconference, they
log onto what's called a reflector-which is really just
another name for videoconferencing server software sitting on
an intranet server.
Reflectors can handle multiple videoconferences. Videoconferences
can be on an ad hoc basis, with people logging in when they want,
or they can be scheduled ahead of time. When someone joins a conference,
they will see and hear everyone else in the conference-and every
person in the conference will be able to see and hear them.
The reflector software is of special benefit to intranet administrators.
It allows for security, so that administrators can block unauthorized
users from participating in videoconferences. Administrators can
restrict access to particular users for specific conferences by
using passwords.
The software also allows for load balancing. When intranet use
is high overall, for example, it can devote less bandwidth to
videoconferencing, to free intranet resources. When use is low,
it can devote more bandwidth to videoconferencing.
The videoconferencing software can be used to broadcast information
as well. The head of your company, for example, could make announcements
live by video to every desktop computer so everyone in the corporation
can watch and listen to the announcement simultaneously.
There are a variety of software programs available that enable
people to engage in videoconferences on intranets. One of the
earliest and most popular Internet videoconferencing software,
CU-See-Me, has also been built to handle intranet videoconferencing.
CU-See-Me allows people with desktop computers to have live videoconferences
with individuals and groups anywhere across the intranet. Anyone
can do videoconferencing with software and hardware that is quite
inexpensive.
- CU-See-Me videoconferencing works on a client/server model.
People run the CU-See-Me client on their computer to log into
a special server called a reflector. A reflector can host
many simultaneous live videoconferences. When you log into a reflector,
you can join any conference that exists. When logged into a reflector,
a signal goes out regularly from your computer to the reflector,
telling others logged in that you are available for a videoconference.
- The video data is sent using UDP (User Datagram Protocol).
Unlike TCP, the UDP does not check for data integrity, nor therefore,
does it ask for bad packets to be resent; it just acknowledges
the receipt of the data. The result is that UDP provides for a
more uninterrupted data transfer and so it provides smoother transfer
and is more efficient than TCP when sending video data.
- You need a video camera, a microphone, and a sound card on
your computer. The camera converts your video image into digital
data. The CU-See-Me software then compresses and encodes that
data, enabling it to be sent across the Internet or intranet.
If the data wasn't compressed and encoded, it would be too large
to be sent. CU-See-Me also saves bandwidth by sending only the
part of the image that has changed. So, for example, if someone's
head moves, it will transmit only the moving head, and not the
background, which hasn't changed. The person who wants to see
your image also has to have the CU-See-Me software. The software
decodes the video image, and displays it as video on the person's
screen.
- The reflector software contains many tools that intranet administrators
can use to better control videoconferencing. It allows administrators
to control the intranet bandwidth devoted to videoconferencing,
both to ensure the highest-possible video quality, and also to
make sure that the rest of the intranet is given the proper resources.
It allows administrators to configure specific conferences at
specific times, and also enables security measures such as password-protecting
the server, so that only authorized users can log in, or so that
only specific intranet users can log into specific conferences.
Reflectors can also automatically adjust the rate of video transmission
to the amount of traffic on the intranet, sending lower-quality
video when traffic is congested, and higher-quality video when
traffic is lighter.
- People on an intranet can participate in videoconferences
with people on the Internet (provided the firewall doesn't block
the packets). To join an Internet conference, people log into
an Internet reflector and participate as they would normally.
If they can have a direct connection, they can participate in
a videoconference by using the Internet person's IP address.
- One-on-one conferences do not require going through a reflector.
If you know the IP address of someone on the intranet who wants
to have a videoconference, you can connect directly to that person's
workstation.
Contact
reference@developer.com with questions or comments.
Copyright 1998
EarthWeb Inc., All rights reserved.
PLEASE READ THE ACCEPTABLE USAGE STATEMENT.
Copyright 1998 Macmillan Computer Publishing. All rights reserved.
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