Re: CuSeeMe audio bit rate

Joseph Kahan (jkahan@phoenix.net)
Sun, 2 Jul 1995 06:56:43 -0600


Tom,

Here are a few quick answers:

>What is the average or normal bps for audio using Cu-SeeMe?

Operating at the 16K audio selection -
100 ms samples, the true average is ~21 Kbps
50 ms samples, the true average is ~24 Kbps
* These numbers are driven by the length of the audio message - basically,
how long you hold down the PTT and the packet overhead required to tranmit
your message. *

>Is this minimum greater than a 28.8 modem can handle with not video?

Again, the above information is required and your modem connection speed to
your Internet provider is important. If you connect at 22 Kbps to your
provider, which is the average for 28.8 Kbps modems, then you will have
problems nogotiating audio and video packets. For this reason, I have
selected a provider which is only 1 PBX station away from my home. This
gives me a constant 28.8 Kbps connection.

>Is there a way to stop the video stream and concentrate on the audio?

Yes, you can freeze your video output by selecting the hold video icon in
your local video window. Remember, this will help pass your audio, but you
will still need to consider your return stream from a sender. Providing
short audio bursts works very well for me.

One other thing that most people don't consider which helps pass low rate
data is your modem's RAM buffer. In most cases, the RAM is 64K and will
hold a second or two of data. This adds latencies to your transmission,
but if you remember what is happening you will find that sending and
receiving CU A/V between two modems works pretty nice. Basically, talk
fast and give your modem a chance to recover between transmissions...

Good Luck,

Joe

P.S. If you try modem-to-modem peer connections you have find some useful
information on my HomePages at http://www.vannevar.com/

___________________________________

Joseph Kahan
Vannevar New Media
Multimedia Communications Solutions
E-mail: joek@vannevar.com
http://www.vannevar.com/

___________________________________