CAP setting

Joseph M Izen (joe@utdallas.edu)
Tue, 5 Sep 1995 10:40:15 -0500


Tim,
You are suggesting a feature here that I've never seen documented:

> In version 80b1, the kbps cap applies only to the video (and
>Talk/Slide window) traffic, but not to audio. By setting your minimum
>transmission rate to 100 kbps, you are saying to blast ahead with the video
>at 100 kbps regardless of packet loss. Then, with the default audio
>encoding at 32 kbps, you would be attempting to transmit around 132 kbps.
>If you truly have 128 kbps available, you would expect a relatively small %
>packet loss, and audio should be mostly intelligible. If, on the other
>hand, you only have 64 kbps available your audio would be useless with 50%
loss.
> I would recommend:

>1) Set your minimum transmission rate to 10 kbps, so that CU-SeeMe can
>attempt to find the capacity of the channel and not send more than it can
>handle. I wouldn't be surprised if you see the cap drop from from 100 to
>around 64. On the other hand, if you really do have > 100 kbps available,
>having the minimum set to 10 should have no effect. Once you have
>determined the capacity of the channel, you might want to set the maximum
>kbps to something under that, to allow room for audio. This will not be
>necessary in version 83, soon to be released, because video is
>automatically throttled back whenever audio is outgoing.

Is there any documentation for the CAP?

Questions that occur are:

Is this only in 8.0b1 or in more recent versions?

Does this feature get triggered by setting min trans rate to 10 kbps, or is
it always there?

If I happen to be doing point to point through at 64kbps pipe using 16 kbs
deltamod, then I should be setting my CAP at 64K - 16K = 48K, right?

If is see CU-SeeMe lower the CAP, should I manually be raising back to the
original value, or does that degrade performance? It would be helpful to
have a display distinguishing between the value I set and the value that
CU-SeeMe thinks the line can handle. For about a half year, I've noticed
that the CAP changes on the fly and thought this was a bug. Now I learn it
really is a feature.

Suppose I am talking to a VAT/nv session through a 64Kbps line. I have the
option of locating my reflector on the mac-side of the link, or or the
nv/Vat side of the link. Which would give better performance, particularly
of sound, and what would be the best settings in this case? Since VAT
doesn't understand 16 kbs deltamod encoding, I would be using intel dvi
32kbps with 100ms audio bursts.

Thanks a lot for your time, and if any of this is covered in a FAQ, please
point me to it!

-Joe Izen