Gnomemeeting Setup

Example: dcg-lab.cs.ttu.edu

Texas Tech University

System Characteristics

Notes

With roadrunner and dcg-lab, the libraries for capturing from Capture Card tend to be cleaner. With KDE's kWinTV one can control the TV input to allow for devices like a VCR to control and record the input signal. It can also be done with xawtv under Gnome.

Also, dcg-lab/roadrunner are both using 8mm camcorders (NTSC compliant ). The RCA (composite) port on the PCTV card can be used for this. When done through this use video channel 1 in gnomemeeting preferences. For the TV tuner use channel 0. Beware that the TV tuner will use whatever channel the tuner was on previously, which is a good reason to use kWinTV or xawtv to change the channel to something appropriate. For the composite input, this is not necessary since the tuner is not used.

Note we have only extensively tested GnomeMeeting using the above hardware-video-capture-card-equipped systems, and are so pleased with the results using a hardware video capture card that we do not plan to go back to the webcam approach (although this is possible within GM). If you spend much time doing videoconferencing, you will probably want also to use a remotely steerable, zoomable camera such as the Sony EVI-D100 (NTSC / Firewire) or EVI-D30, each of which have pan/zoom/tilt capability. You also may wish to consider adding a document camera and video input switch box. (Even with the above hardware additions, the cost of setting up a very nice GnomeMeeting-based system is about a third of what it would cost to purchase a commercial H.323-capable system with similar camera and audio capabilities.)

The sound has two gotcha's. First, the composite version has the feed through the microphone. You can choose to place this input in the line or CD port, too. However, it does not make much difference. The gotcha is the "igain" section of the mixer. You can use whichever mixer control you wish, but the igain section has just as much to do with audio input as does the microphone/line/ CD ports. This gotcha is more pronounced with the tuner. The audio is fed in both ways. Thus to mute, either use the gnome meeting mute or both the microphone and igain mute provided on the sound mixer. Second gotcha is the tuning of the microphone and speakers. These have to be adjusted to ensure that echo is not generated. In TTU's case, long cables were used to put an increased amount of distance between the microphone and speakers. For an individual sitting at the computer, a low volume setting and adjustments to the microphone/igain setting will suffice. However for a conference area, placement of the speakers and camera tend to be subtle gotcha's which can be annoying to the people on the other end of the conference.

TTU's Distributed Computing Lab found a work around for this by using the an echo canceling microphone originally used with Wave 3 Software's Session SIP software. In this case, the speakers and microphone are connected with the electronics of the microphone used to filter out any local echo. This does not get rid of echos heard at remote sites, but greatly helps to remediate locall-generated echo problems. Further improvements can be achieved by adjusting microphone positioning, speaker volume, the echo cancellation settings within GnomeMeeting, or all of the above. With care, echo can be eliminated almost totally. (See also the "Common Sense" section below.)

The setup so far with Fermilab's "Fermi Linux" (basically Red Hat) has some trouble. In particular, the dialing is at issue, as is the capture. The capturing does occur. However, it does not make it to the transmission stage. Receive has not been tested yet. We have recently switched to a newer version of Fermi Linux at TTU and will continue this testing.

Gnome Meeting Settings

The settings in Gnome Meeting that seem to work for us are listed below.

General

Personal data: put your name there. Note the Gatekeeper alias is your ESnet ID.

Directory settings:

Registering Method: Gatekeeper host
GateKeeper ID : Your ESnet user ID (e-mail form preferred) from your registration
Gatekeeper host : 198.128.3.86
Gatekeeper alias : Your ESnet room number (numeric form, e.g. dcg-lab's is 200418)
no password required

* Note: Registration with gateway can be turned off after the first 5 seconds of the system trying. If the system does not complain, then keeping the registration is a relative consideration. If the system complains due to firewall constraints, then allow the first 5 seconds of trying and turn off the registration. The gatekeeper will have the data even if it is not confirmed.

* Note: You can use the XDAP component for a listing of different meetings (like an address book). This type of server is similar to a LDAP server. At this moment, TTU is not using one, but may in the future.

Codecs:

-> audio: G.711-uLaw-64k enabled
G.711-ALaw-64k enabled
optionally disable all other audio codecs

* Also: move the G.711 codecs to the top of the list. This seems to be important!

-> video: check "enable video transmission" ...
transmitted video quality: 100
received : 100
transmitted bg blocks : 20

devices: (depend on your hardware)
-> audio player: /dev/dsp0
player mixer: /dev/mixer
-> audio recorder: /dev/dsp0
recorder mixer /dev/mixer
-> automatic echo cancellation: automatic gain compensation

* Note: This is at the users discretion. If the audio is set correctly in the room, then no echo exists. Otherwise, it is helpful to balance the noise cancellation. Sometimes the automatic gain compensation helps. Other times it does not.

-> video device /dev/video0
video channel 0
video size large
video format NTSC (for US cameras, for European cameras use PAL)

Calling Format

Gnome meeting uses a so called "callto" protocol for dialing. The format is as follows:

callto://ESID@gatekeeper

example: SAM-DH = callto://8272634@198.128.3.86

Supposedly, if there are no firewall issues then callto://8272634 should have the same effect. Also, this format is supposed to allow things such as hyperlinks to activate gnomemeeting automatically and dial a specific number.

Button gotcha:

The audio mute and transmission mute are two separate things. The button with a speaker is for your received audio, the one below it is for transmitted audio. Be sure to have the camera preview on while in conference. Otherwise, a blue screen will be transmitted.

Common sense:

Remember to mute if you are not talking. Really!!

Also speaker and microphone placement and quality make a difference. Try to separate them as much as possible to avoid feedback, and use the echo-cancelling settings within GM as above if necessary to get rid of local echo problems. Remember to mute (did we say to remember to mute if you aren't talking?).

Last updated 2003-03-12