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Contents

Chapter 3

LBL

Introduction to the LBL Software

The LBL suite of videoconferencing software originated at Lawrence Berkeley Laboratory, University of California. It is public domain software. For details on how to obtain the programs, see the 'Features' section below.

We installed the suite on our SUN Solaris workstations and it took advantage of the SunVideo board for video capture. There are a number of different versions of the software corresponding to different platforms (see the tables in Chapter 4 for details) and the video tool allows several different compression algorithms and different frame grabbers to be used.

On our system, no special audio hardware other than a microphone is required since the sound I/O takes advantage of the built-in audio hardware.

Documentation

As with IVS, the documentation is relatively poor. It is highly technical in some sections and comes online with the package in the form of a few man pages, lists of technical changes and some notes about use. There is a User's Guide for the whiteboard tool which looked promising but was short on detail. The following quotes are taken from the documentation:

"The video tool, nv, allows users to transmit and receive slow frame rate video via UDP/IP across an internet."

(man page for nv)

"The audio tool, vat, allows users to conduct host-to-host or multicast teleconferences over an internet."

(man page for vat)

"If you simply want a shared 'whiteboard' drawing surface, you don't need to do anything but install wb"

(in the ReadMe file for wb)

Standards

By default, the video tool sets the encoding to the native compression for the platform. This means that it supports CellB compression for a Sun workstation. It has decode support for a number of different video encoders but does not support the H.261 standard yet. The audio tool supports the PCM, ADPCM, DVI, GSM and LPC encoding schemes.

Features

The LBL software consists of

wb whiteboard
vat audio tool
nv network video tool (this comes from Xerox)
sd session directory
wbimport help with importing PostScript files into wb

We have not gone into detail about the video, whiteboard and audio components of LBL since the tables in Chapter 4 can be used for a comparision of features. Note that there is no associated shared application tool available.

The Session Directory allows a file to be created which contains a dynamically updated list of sessions (or conferences). A new session can be created, advertised, edited and deleted.

The whiteboard, audio and video tools, (wb, vat and nv), can be run independently of one another. It is more usual, however, to use the session directory tool, sd, where one or more of these tools can be requested, simultaneously.

All these tools are obtainable as public domain software. The tools, wb, vat and sd, (with other programs), can be transferred using the following commands on a unix system.

mkdir ~/lbl 
cd ~/lbl 
ftp open 
ftp.ee.lbl.gov 
.... give anonymous as your username 
.... give your email address as your password 
cd conferencing/sd 
ls 
binary 
get (whichever binary corresponds to your machine type) 
cd ../vat 
ls 
binary 
get (whichever binary corresponds to your machine type) 
cd ../wb 
.... etc

nv can be obtained by ftp from parcftp.xerox.com on the directory pub/net-research/nv-3.3beta

Just as with IVS, you will have to uncompress the software and obtain the various components.

Calling a Conference

Figure 3.3 Creating a session in sd

To call a conference, the sd program is run and on asking for a new 'session', a window appears as shown in Figure 3.3. This allows the specification of the range and duration of the conference. Once a session has been created, any workstation which has sd running and which falls into the specified range (local site, region or the world) will receive a message advertising the new conference. This is the way to call a multicast conference. It is possible, also, to specify one's own TTL ('time to live') number instead of opting for the local, region or world range. Please see Appendix 4 on Multicasting for more details on the TTL number. At the time stated, the selected tools (audio, video or whiteboard) are started.

If sd is left running, sessions from other sites may be advertised, depending on what range they have specified and a free decision can be made as to whether to join the session.

Another way of calling a conference is to invoke one or more of the tools, nv, vat and wb, specifying the destination and port on the command line for each tool.

Improving Performance

The nv tool has support for different video encoders, including SUN CellB. As usual, it is possible to trade off between quality and frame rate. The nv tool has an options panel or it can be invoked with parameters to specify limits for the bandwidth and frame rate, the size of the video picture and whether the picture should use greyscale or colour.

There is a menu associated with the vat tool to help improve the quality and transmission of the audio - this is the most comprehensive set of features that we have seen and it was a pity we did not have time to experiment. Amongst the features is the ability to suppress echo if no headphones are available, to control the volume gain and to suppress background noise.

All these different options can be adjusted by setting parameters on the vat command line as well as selecting menu items. For the more technically oriented reader, these options can be set either for the individual user or system-wide by specifying the X Resources to be used and storing them in the Xdefaults file.

A notable feature of vat is that of being able to have a private conversation with one of the participants in a multicast conference which other participants cannot hear. This would be useful, for instance, in a helpdesk environment if a consultant needed to consult privately with a colleague about the best advice to give.

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