Re: ISDN, etc.

Richard Cogger (EST)
Wed, 16 Nov 1994 11:27:14 -0500

Right, audio requires 32K of *payload* per second and is very sensitive to
packet drops. You would probably be able to get audio if you close all the
receive video windows, or if you have only one open and that person caps
transmission at 10 or 15K. Future developments will include optimization
for 64K operation. One obvious thing will be to have reflectors give
priority to audio. Otherwise, we expect a lower bitrate encoding (but you
may need a powermac to run it), some forward error correction, and yes, a
postage-stamp size option at a low frame rate. -Dick

At 4:17 PM 11/15/94, Jon Tower wrote:
>Jeff Brown writes:
>> 4) Supposedly, to get both video and audio on a dial-up c
>> onnection 32kbits is required, meaning that even the fastest modems
>> will be too slow.
>> However, since I will have an ISDN line with two 64K channels (which
>> can be bonded for 128k) I should have throughput to spare. True
>> fact? Has anyone done this?
>> Jeff Brown
>I discovered that even at 64K (or 57.6K, since MacPPP cannot be set for
>higher than that) I do not get intelligible audio! It's still chopped up --
>not much better than when I was using a 28.8 modem. I was very disappointed
>to discover this. Regarding the video, there is a difference between 28.8
>and 64K ISDN. Depending on time of day, etc, I do get "realistic" video, with
>frame rates of several frames/second.
>So if you know how to get *affordable* 128K net service into your house, then
>you'll get the full benefits from this software. (and please let me know!)
>And ISDN is worth getting, in general: For other applications like Mosaic,
>Fetch, it's great! But unless there are future developments, CU-SeeMe is not
>yet optimized for 64K ISDN.
>Jon Tower, New York
>voice/fax: 212-463-8762
>POB 1872, NY NY 10013