This documentation is a revised edition of the
MICE documentation of
National Support Centre London
Revision by Jens Elkner (elkner@irb.cs.uni-magdeburg.de).
User Guide to vat
vat is the visual audio tool developed by Van Jacobson and
Steven McCanne (both of Lawrence Berkeley Laboratory, University of
California, Berkeley, CA.) to provide audio teleconferencing over the
Internet. This X11-based tool has gained from the attentions of other
developers since its first appearance. It is the current standard
audio tool for MICE conferencing.
What does it do for you?
Vat allows users to conduct one-to-one, one-to-many or many-to-many
audio teleconferences. It provides a visual window by which the user
can control his interaction with an audio conference or link to a
single other user on the network.
While vat is used as an independent audio conferencing tool, it is
frequently used as the audio part of a full videoconference.
If you intend to use it in such a context, you are advised to review
the Guide to Multi-media Conferencing.
The use of this tool for conferencing depends on the existence of a
facility to multicast the sound from each participant to all others
without having to broadcast it to every workstation on the network.
This facility is known as the Multicast Backbone or
Mbone.
To use vat you will need a workstation capable of receiving sound.
For conferencing it must also be able to transmit sound.
You will also need to install the correct version of the software
for your workstation.
You should use of the
LBL Session Directory to publish
and monitor network multicasts.
How do you use it?
The invocation may be from a command line or from the
LBL Session Directory.
There are many command-line parameters which are
described in the vat manual pages.
The title of the conference is shown at the top, left of the
vat window.
This is set up using a command-line parameter (-C) when vat is invoked.
The window itself is divided into two parts: the right has controls
for the local audio and the left has a status display of the hosts
participating in the current conference.
Below the audio controls are three other buttons:
Logging
You can produce a log of all current part
icipants by moving the mouse pointer into the window and typing
L (upper case).
The output is written to the window from which vat was invoked.
Known Problems
The following are known problems with vat. If you know of any others
please let us know.
Poor audio quality when using the Sparc 5
- SunOS 4.1.3U1
- Sparc 5 audio still doesn't work properly but with SunOS 4.1.3U1
at least it works tolerably.
You need to apply the following patches: 102161-01 and 101508-07.
Once you have done that I have found that setting the kernel variable
audio_4231_bsize to 1200 will make the audio device work tolerably
(you do hear a slight clicking sound about once per second if there is
any playout time above a few hundred ms). To patch the kernel you need
to:
adb -k -w /vmunix /dev/mem
audio_4231_bsize/W 0t1200 (to patch the running kernel)
audio_4231_bsize?W 0t1200 (to patch kernel file on disk)
Graeme Wood, Scottish MICE National Support Centre
(mice-nsc-scotland@ed.ac.uk), November 1994
- Solaris 2.3
- As far as Solaris 2.3 is concerned, I do not think anything has
changed recently.
David Meyer at U. of Oregon
(meyer@frostbite-falls.uoregon.edu)
has been pushing Sun on this front and he may have more
information than I.
Graeme Wood, Scottish MICE National Support Centre
(mice-nsc-scotland@ed.ac.uk), November 1994
- Solaris 2.4:
- There is a small audio patch related to 'pops': 102037-01.
I must say that for the most part our SS5 with Solaris 2.4 has very nice
audio from vat *except* after any long-ish (technical term, that :-) )
pause it briefly (<3 sec)
garbles the sound somewhat, but comes good again of
it's own volition - no need to resize windows or jiggle sliders.
I haven't had a chance to test other audio tools yet (xcdplayer
and ShowMe).
Markus Buchhorn, Australian National University, Canberra
(markus@octavia.anu.edu.au), February 1995
We would like to hear from you regarding your experiences in using
this documentation.
Comments of any kind and all technical enquiries should be addressed
to mice-nsc-uk@cs.ucl.ac.uk
Acknowledgement
The development of wb, vat, and sd was supported
by the Director, Office of Energy Research, Scientific Computing
Staff, of the U.S. Depart ment of Energy under Contract
No. DE-AC03-76SF00098.