MBONE: Multicasting Tomorrow's Internet

MBONE Tools for UNIX

Video, audio, and a shared whiteboard are the principal MBONE applications, but a variety of programs are available for fulfilling these functions. Each program is available as ready-to-run executable programs, or as source code from various anonymous FTP sites.

IP Multicast extensions

If your workstation only knows how to handle unicast packets, you'll have to add special software to its kernel before it can handle multicasting. IP multicast extensions are available as kernel patches for a variety of flavors of UNIX. Depending on your system, you may be able to find precompiled multicast additions; if not, you'll get to experience the joys of compiling them in yourself. Think of it as a character building experience.

You can find IP multicast extensions for UNIX via FTP at ftp.parcftp.xerox.com under /pub/net-research/ipmulti3.5-*.tar.Z. Other sites where you can find the multicast extensions include: louie.udel.edu:/pub/people/ajit/ipmulti3.5-*.tar.gz and ftp.adelaide.edu.au:/pub/av/multicast/ipmulti3.5-*.tar.gz.

The distribution includes kernel modifications for SunOS 4.1.3, SunOS 4.1.3_U1B, and SunOS 4.1.4, as well as the mroute daemon and various supporting binaries.

Once your workstation knows how to send and receive multicast packets, you'll need to get the software tools to make use of the MBONE. A wide variety of software is available -- the major packages for MBONE multimedia are covered next. The standard multimedia setup for conferencing on the MBONE includes whiteboard (wb), the visual audio tool (vat), and session directory (sd). Make sure that you pick up these three essential tools.

nv network video

The network video package, nv, was developed at Xerox Palo Alto research Center. nv is a videoconferencing tool that uses a default bandwidth of 128 Kbps and offers video rates of 3 to 5 frames per second. Versions are available for Sun, Silicon Graphics, DEC, and Hewlett-Packard systems. We've heard from the grapevine that programmers are working on a version for the Macintosh, one of the earliest signs that multicasting tools will soon be available to "the rest of us." Currently, however, no DOS, OS/2, or Windows versions are available, although a PC running Linux or 386BSD UNIX can use nv.

The following excerpt is from the nv main page:

nv allows users to transmit and receive slow frame rate video via UDP/IP across an
internet. Video streams can be either sent point to point, or sent to several destinations
simultaneously using IP multicast. Receivers need no special hardware - just an X display.
Transmitters need some sort of frame capture hardware. Several different boards are
supported so far, with more to come in future releases.

By default, the video transmitted is a 320x240 image for NTSC, or 384x288 for PAL. It can be sent either as 8-bit greyscale, or 24-bit YUV 4:2:2 color. Other sizes (both smaller and larger) can also be selected. It will be displayed at the receiver using a 24-bit color visual if one is available. If not, it will be dithered using whatever the default visual is. The frame rate varies with the amount of motion and the bandwidth available. Frame rates of 3-5 frames/second are typical for the default bandwidth of 128 Kbps. Some systems will support higher frame rates if the bandwidth is raised or smaller images are sent.

You can get nv via FTP from ftp://parcftp.xerox.com/net-research/nv*

wb whiteboard

The whiteboard tool, called simply wb, creates a shared, virtual whiteboard on your computer screen. wb is frequently used as a visual aid to accompany MBONE video lectures -- and occasionally for Friday afternoon doodling. Besides offering standard drawing tools (likes, circles, and so on), wb can also be used to share PostScript files -- speakers can show PostScript "slides" on wb to accompany live video images sent using nv.

The following excerpt is from the wb README file:

If you simply want a shared "whiteboard" drawing surface, you don't need
to do anything but install wb. But wb can also be used to export, view and
annotate arbitrary PostScript files. If you want to include PostScript
images in your wb conference, either your X server has to support Display
PostScript (the DEC & SGI X servers do) or wb has to be able to exec the
public domain postscript renderer 'GhostScript'. If you want to render
postscript with Ghostscript, it has to be installed on your machine and
has to be in your shell search path with the name "gs". (If you don't have
Ghostscript it can be ftp'd from prep.ai.mit.edu, file pub/gnu/ghostscript-*.tar.Z.).

Versions of wb are available for Linux, Sun, Silicon Graphics, DEC, and Hewlett-Packard systems, with ports in progress for Macintosh. You can find them via FTP at ftp://ftp.ee.lbl.gov/conferencing/wb.

vat visual audio tool

The visual audio tool, or vat, was developed at Lawrence Berkeley Laboratories in California. Vat is a program for sending and receiving audio via the MBONE. "vat" is a bit of a misnomer because although its interface is visual (that is, graphical), vat does only sound, not video.

vat enables private communications between two hosts (well, as private as anything zipping unencrypted over the Internet can be), as well as public audioconferencing. vat provides a variety of compression formats, allowing it to interoperate with several platforms and programs. vat will even let you chat with users on Windows or Macintosh PCs, assuming that they have audioconferencing software on their end, too.

vat provides conference hosts a list of all the other hosts that are currently tuned in to a multicast session -- a nifty way to tell how many others (and who) are listening to your lecture, diatribe, or ad-hoc Internet Radio show. Ready-to-run versions of vat are available for Sun, Silicon Graphics, DEC, Linux, and Hewlett-Packard platforms, with ports in progress for Macintosh. On most architectures, no special hardware other than a microphone is required -- sound I/O is provided via the built-in audio hardware.

You can get vat via FTP from ftp://ftp.ee.lbl.gov in the conferencing/vat* directory.


Developed at the University of Massachusetts, NeVoT, which stands for "network voice terminal", is another program that provides multiperson audioconferencing. It supports a wide variety of audio protocols, including 16-bit linear encoding, 64 Kbps mu-law PCM, 32 Kbps ADPCM, 32 Kbps Intel/DVI ADPCM, GSM, and others.

You can receive NeVot via FTP from ftp://gaia.cs.umass.edu/pub/hgschulz/nevot or ftp://ftp.fokus.gmd.de/pub/minos/nevot. Precompiled versions are available for SPARCstations, Hewlett-Packard 9000 running HP-UX, SGI running Irix 5.2, DEC Alpha running OSF 1.0, DECstation running Ultrix, IBM workstations running AIX, and Linux workstations.


The INRIA Videoconferencing System (ivs) is an audio and videoconferencing package for FreeBSD, DEC, SunOS, Linux, other platforms. ivs is frequently used for participation in MICE (Multimedia Integrated Conferencing for Europe) seminars. It provides a video resolution of 320x200 pixels, in 256 or millions of colors, and provides a respectable 20:1 compression ratio. Only minimal hardware upgrades are required to a machine commonly found on the desk of an engineer: a video camera and a frame grabber.

ivs is available by anonymous FTP from zenon.inria.fr:rodeo/ivs/last_version. For more information about ivs, visit the ivs home page at http://www.inria.fr/rodeo/ivs.html.

sd: session directory

The sd -- which stands for session directory -- tool is sort of the "TV Guide" of the MBONE. Session directory displays a window showing current and planned MBONE sessions. The sd tool provides a straightforward interface to the Internet Group Management Protocol, which allows users to use their workstations to join and leave multicast groups. A user can click on a session name for information about the multicast (such as the planned time and date). The user can see, hear, or participate in a current session by double-clicking on a session name, which automatically launches the appropriate tool -- nv, vat, wb, or whatever.

Sd is available precompiled for Sun, SGI, Linux, DEC, and other operating systems. You can get it via FTP from ftp://ftp.ee.lbl.gov/conferencing/sd.

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