Re: Another question . . .

Richard Cogger (R.Cogger@cornell.edu)
Wed, 12 Jul 1995 06:39:04 -0400


>awarded a grant to pursue a project idea centered around a simulated
>journey to Mars. During the simulation, I wanted to use CUSM to hold
>video conferences with NASA scientists, engineers, and technicians to
>discuss spacecraft and habitat design, propulsion systems, trajectories,
>and so on.
>
>> >Would a 28.8 Kbps SLIP or PPP connection be fast enough (have enough
>> >"bandwidth"?) for sending or receiving simultanous audio and video,
>> >assuming I had a Mac Quadra or other high-end Mac?
>
The definitive answer to this question is "it depends."

I can imagine that in your simulation, you might set up to be "mission
control" and have someone else playing the part of the Mars mission. At
28.8, you will need to use a low rate audio coding, currently the 16K
deltamod; and it will give intelligible voice-- it may sound about like
early 70's spacecraft communication, if you work your imagination a bit
("must be noise from sunspots, eh?"). You can also get low rate video. It
would even work after a fashion for a 3 party conference (assuming you can
use someone's reflector). Someone clever at NASA could add some code to
the reflector to increasingly buffer up transmissions in a reflector to
simulate the delay increase as the spacecraft gets further from home.

If you want something fairly useable, though ISDN or better would be a good
idea. Going with ISDN, you want a rig capable of bonding the 2 B channels
you get with a BRI to give a total of 128Kbps and a supplier that supports
it. With 128K, you will still be limited to 3 or 4 windows to get anything
looking like movement, or you can get half a dozen windows up and it will
work like 28.8 with one window. You should talk to the folks at Global
Schoolnet (Yvonne Andress), as they have quite a bit of experience using
CU-SeeMe and other Internet stuff in the classroom. (andresyv@cerf.net)

Right now, a Mac gives the best results, as the software is most advanced.
The faster the Mac the better. In a few months, we should have equivalent
functionality under Windows. Sometime in the fall, we expect to have a
better sounding lower rate audio codec on both platforms. On the Mac, you
can use the inexpensive QuickCam ($100) instead of a video-capture board
and camera ($600). QuickCam for PC is expected sometime, but not here now.
On PC, you also need Audio board and mic, which is pretty much there on
recent Mac's.
>
>
>Also, I understand that Cornell is coming out with a Talk Windows version
>sometime in July. What kind of PC system could send and receive
>simultaneous audio and video? Would a 486 suffice, or would I need to
>move up to Pentium? If I can't get a Mac, I may have to upgrade the PC's
>already at my disposal.

A 486 DX266 or better should be OK. However, you can expect audio for the
PC in July (I hope) but not the Talk Window. That will possibly be more
like Sept/Oct unless it goes faster than expected (so far almost nothing
ever has). What exactly is best choice for capture board, camera, and
audio board plus mic, is hard to say. We have advance samples of a very
nice all in one package that should retail under $400, but don't know when
it will be avialable. The boards we started with (blaster, spigot) are no
longer being made. Perhaps folks on the list will report various current
best setups for PC's?

Good luck, -Dick