CU-SeeMe
In this section we demonstrate the use of a freeware teleconferencing tool, CU-SeeMe, that is available for both Macintosh and PC platforms. CU-SeeMe is a clever play on words, since it is phonetically rather descriptive of what the software does, and it was developed at Cornell University (CU).
CU-SeeMe basically allows two computers to teleconference, but multiple computers may be connected by the use of reflectors, which are computers on the network running special software that allow a CU-SeeMe transmission from one computer to be "reflected" to many computers. One must distinguish the CU-SeeMe client software, which runs on Macs and PCs under the usual Mac OS and Windows operating systems, from the reflector software, which typically resides on network servers running either Unix or Windows NT operating systems. Our discussion will be concerned primarily with the client software; however, ambitious and well-supported educators may wish to enquire about setting up a reflector site.
A commercial version of CU-SeeMe is available that offers additional features such as technical support, color imaging (the freeware version is 16-level grayscale), and a shared whiteboard (a window in which anything placed by a conference participant becomes accessible to all). Our tutorial will be based on the freeware version CU-SeeMe 0.83b3.
The network must recognize TCP/IP protocols, since the CU-SeeMe software assumes that. It is highly desirable that the network be fast, but that should influence only the quality of the teleconferencing, not whether you can do it, provided the network supports TCP/IP. In particular, this demonstration can be implemented over modem connections if they use TCP/IP protocols (e.g., SLIP or PPP connections). However, 28.8 kbaud is probably the minimal speed that you can expect to transmit unbroken sound, so anything less than ISDN speeds (56 kbaud or better) will probably leave much to be desired in terms of quality.
We shall assume that two computers are available satifying the above requirements and have the appropriate software installed. For the purposes of this demonstration, the two computers could be in the same room, or they might be very distant from each other. (You can even use a single computer to demonstrate many of the principles by making a connection to yourself after the local video window is opened.)
Before doing very much with CU-SeeMe, you may wish to become familiar with these general rules of CU-SeeMe Netiquette.
The "Flip Image" button reverses the image in the display (but not in the
transmitted image).
The "Status Line Toggle" determines
whether the status bar underneath it is visible. The status bar is described
below.
The "Freeze Video" button suspends your video transmission; this is often
useful to free up bandwidth if the network is too slow.
The "Options Toggle" displays an options area
where the
brightness, contrast, and other video & audio properties
can be adjusted
using pop-up menus.
Good manners dictates that the cap on transmission rates normally not be more than 80kbps (kilobits per second), in order not to hog bandwidth from other users. The default settings will usually respect this, and reflectors may automatically disconnect you if this setting is changed to a number larger than 80kbps (it is set in popup windows under the "Options Toggle" described above).
A common use of the video button is to freeze
transmission of your video on a still frame to free up bandwidth for audio.
To a good approximation,
only the part of the image changed from the last camera image
sampling is transmitted, so
if the frame is frozen it will display continuously as a video stillframe on
other participants screens and your video transmission rate will drop to
almost zero.
Now we are ready to make a connection to another user. Open the "Conference"
pulldown menu and select "Connect" (left figure). The popup dialog box shown
in the right figure should appear. Type into the "IP Address" window the IP
address of another computer that is running CU-SeeMe,
leave the "Conference ID"
at 0, check that you will both send and receive video, and finally select
"Connect". If the other user chooses to accept your connection, a user
window will pop up on your screen in addition to the local user window. A
connection will then correspond to two independent windows that look
something like the figure shown below.
In this example, the local user "Homemama" has established a connection with a remote user called "Le Chat". Do you notice anything unusual about this CU-SeeMe session? That's right! Even a teenager can be trained to use CU-SeeMe, provided that one has sufficient patience!
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The video status icon indicates whether the user is accepting video input (eye open) or has paused video input (eye closed). This symbol, we are reluctant to report, is called the "eye-con"! |
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The audio button toggles sound on and off for the particular user. |
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The microphone icon; it is crossed out with a large red "X" if the user is not transmitting sound to anyone, and a small red "x" if the receiver is not transmitting sound to you only (if there are multiple connections using a reflector, as described in the next section). |
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A meter indicating the video and audio transmission rates. |
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The transmission statistics button toggles a window giving technical information on the transmission of data. |
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The user information button displays technical info about the user to which you are connected: IP address, version of CU-SeeMe, transmission rate limits, . . . |
These buttons display information and allow control of the connections to other users.
The "Participants List" window illustrated in the adjacent figure lists the
participants in any teleconference, and their present status: "Visible",
"Hidden", or "Lurkers" (hidden or lurking participants are in receive-only
mode). If the window is not visible, toggle it on under the
"Participants" pulldown menu. The Participants Window also displays icons
giving the status of each participant (see discussion above). In the example
shown here there are multiple participants, so this corresponds to a
CU-SeeMe session using a reflector (see the next section).
The triangle icons to the left of each category allow the list below it to be
toggled between "displayed" and "folded up".
As participants enter, leave, or change their
status in a
teleconference, the Partipants List will change accordingly.
Audio transmission and reception is controlled using the Audio Panel, which can
be displayed or hidden by toggling under the "Conference" pulldown menu.
You may select "Push to Talk" mode (left figure) or "Live Mic" mode (right
figure) by toggling the "PTT" switch at the lower left of the audio panel. In
the first mode you must push the "Push to Talk" button with the mouse and hold
it down to transmit audio; in the second mode audio is transmitted
continuously. (Note: if the connection is too slow, audio quality may be
poor. Freezing video, as described above, may help in this situation.)
Diamond-shaped slide
switches on the two sides of the Audio Display allow control of volume
for your transmission (the microphone icon) and reception from other users (the
speaker icon). In each case a sound meter display indicates the volume level
when sound is transmitted (see the green bars in the right figure). Slide
arrows on the right allow squelch thresholds to be set for voice transmission
in open mic mode. Toggling the right-arrow symbol at the bottom opens a display
with further control options; toggling the "Lurkers" button turns on and off the
choice of whether lurkers (receive only) can connect.
First, you can send short text messages
simply by typing on the keyboard when the
video window is in the foreground (see figure at left).
The text is not retransmitted so you don't
see it in the user's window, but it appears in your video window, and it
appears
in your window displayed on the other user's computer. The text is displayed
in a single line at the bottom or top (the up and down arrows can be used to
switch). You can also animate a scroll by using the left and right arrows, but
this uses increased bandwidth and should be employed sparingly.
Second, the newer releases of CU-SeeMe include a Talk utility
that allows 2-way typed communication. If you choose
"Open Talk Window" under the
"Talk" menu, a split-screen display appears (see figure at right).
Anything that you type in the
upper portion of the split screen appears in the lower portion of your
conferee's split screen (after a return), and anything typed by your conferee
into his upper screen appears in your lower screen. Thus Talk allows
a 2-way, real-time communication similar to a
chat session.
The nicknames list is stored in the "CUSeeMe Nicknames" file in your system "Preferences" folder. You can move the nicknames list to another Mac running CUSeeMe by copying that file to the Preferences folder of the new machine.
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