experiences with MBONE and CU-SeeMe

Kent Wada (wada@mic.ucla.edu)
Thu, 26 Jan 1995 18:43:56 -0500


After sending various questions to this list in the past, I thought I
would return the favor and describe some of our experiences in joining
the CUSM and MBONE worlds together.

The good news, as many of you are probably already aware, is that it
is indeed possible to exchange bidirectional audio and video streams
between the two worlds. At our height, we had

2 SPARCstation 20s with Solaris 2.4, nv 3.3beta, vat 3.4
with SunVideo boards/SunCameras and SunMicrophones
1 Centris 650 with System 7.11, 0.80b1 CUSM
with integrated CCD camera/microphone
1 PowerBook Duo 230 with System 7.5, 0.80b1 CUSM
with builtin microphone
1 PS/Valuepoint DX2/50 with FreeBSD 2.0, nv 3.3beta
1 PS/Valuepoint DX2/50 with Windows 3.1, 0.34b4 CUSM

all receiving, and some sending, audio and video through a 3.00b3
reflector running on a SPARCstation IPC (SunOS 4.1.3). Thanks to the
recent reflector work which no longer requires us to use a vat mixer!

We have also done a very preliminary "telecommuting" test whereby a
CUSM client running on a Quadra 900 with a microphone was connected to
the same reflector above via a 28.8 modem over a fractional T1 to the
Internet. A low-rate video stream generated on a Sun came across quite
nicely on the Quadra, but audio in both directions was quite
horrendous. We ended up talking on the telephone simultaneously to
gauge the effects, and found, without much surprise, that the apparent
degredation probably involved dropped packets as well as an
"elongation" effect.

The caveats:

1) For bidirectional video, you must tell nv to send a CUSM-encoded
video stream rather than a native nv-encoded stream. In particular,
this means that CUSM clients wouldn't be able to interpret most video
being broadcast over the MBONE.

2) It took us a while to figure out that the PC CUSM client will not
accept a "high resolution" image. When we sent a smaller image video,
things worked fine.

3) We have successfully run a reflector off of SunOS 4.1.3 and AIX
3.2.5 systems. A reflector running under Solaris 2.3 or 2.4 dies
shortly after an nv video source becomes active, although it seems to
work fine with CUSM clients only.

4) The system running the reflector is unable to see CUSM streams in
nv itself, presumably because it is not looking at the multicast
packets it is putting out.

-Kent

--
Kent Wada <wada@mic.ucla.edu>
Coordinator, Advanced Workstation Program
UCLA/OAC Microcomputer Support Office
Tel: +1 310 206 3874 / FAX: +1 310 206 1700
WWW: http://caviar.mic.ucla.edu/