[asterisk-users] Amazon AWS question

Dan Cropp dan at amtelco.com
Wed Aug 28 09:47:23 CDT 2019

Thank you Joshua

-----Original Message-----
From: asterisk-users <asterisk-users-bounces at lists.digium.com> On Behalf Of Joshua C. Colp
Sent: Wednesday, August 28, 2019 9:15 AM
To: asterisk-users at lists.digium.com
Subject: Re: [asterisk-users] Amazon AWS question

On Wed, Aug 28, 2019, at 11:09 AM, Dan Cropp wrote:
> Thank you Joshua.
> Out of curiosity, when the capacity is reached is it a CPU issue?
> Or some other resource (memory) issue?

It wouldn't be memory, it'd be CPU most likely.

The way ConfBridge works is that each conference bridge has a mixing thread that wakes up at a specific interval (20ms generally). That thread then pulls 20ms of audio from each participant, mixes it together, and provides a unique one to each participant (removing their audio). Audio is fed into a buffer from each participant as received for the mixing thread.

If the time it takes the mixing thread to do things increases, then the stream of packets will go out of wack, and if it's worse enough then the endpoints can't compensate (if it takes 30ms to produce a 20ms chunk of audio, you're going to have a problem).

What this threshold is depends on the system.
> Also, would the ConfBridge Bridge and/or ConfBridge User jitterbuffer 
> setting help/hurt the capacity?
> From what I understand jitter buffer support can result in higher CPU 
> usage handling the jitter.
> Is this correct?

Jitterbuffer inherently introduces a buffer, so it will increase memory usage and also increase CPU usage some as the jitterbuffer becomes the one feeding media.

Joshua C. Colp
Digium - A Sangoma Company | Senior Software Developer
445 Jan Davis Drive NW - Huntsville, AL 35806 - US Check us out at: www.digium.com & www.asterisk.org

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