[Freeswitch-users] Choppy audio when conferencing 4+ participants

[Mundkowsky, Robert]

Thanks Colin.

I figured that was the case, but it is surprising how many things work without a good precise clock. Although might be most non-RT protocols expect slews and such.

Robert

From: freeswitch-users-bounces at lists.freeswitch.org [mailto:freeswitch-users-bounces at lists.freeswitch.org] On Behalf Of Colin Morelli
Sent: Friday, April 14, 2017 4:53 PM
To: FreeSWITCH Users Help <freeswitch-users at lists.freeswitch.org>
Subject: Re: [Freeswitch-users] Choppy audio when conferencing 4+ participants

Robert,

While I'd love to see VMs provide more stable ground for FS, it's simply not the best task for a VM. Virtual machines scale well specifically because you can overprovision them. It would not be nearly as cost-effective to run VMs if each instance had a guaranteed dedicated slice of hardware to operate on. While hypervisors are very good at task prioritization, they're not perfect. If the hypervisor can't schedule processor time when FS needs it because the CPU cores are momentarily taken on other tasks, there's not a whole lot FS can do. This is not an issue with just FS, but with all real-time applications. In most apps, even large clock skews and bad hypervisors schedulers can go completely unnoticed. If there's consistent 5-10ms every time you click to load a web page, you'd probably have no idea. If there's 5-10ms jitter every time you try to read 20ms of audio, you have really bad audio. Granted most skews are not that bad, but the effects are pronounced when you're dealing with data that's real-time in nature.

Bilal,

I have no idea what AMI you're running, but a very rough "ear test" has made me fairly confident that I can get better performance running AmazonLinux AMIs over Ubuntu (and probably many others). It wouldn't surprise me if AmazonLinux builds a custom kernel that has been tuned to run better on AWS hardware. I'd say it's at least worth a quick experiment.

Best,
Colin

On Fri, Apr 14, 2017 at 4:34 PM, Mundkowsky, Robert <rmundkowsky at ets.org<mailto:rmundkowsky at ets.org>> wrote:
Michael

Just curious, why so many problems with VMs?

I would think most applications need real time clocks that provide consistent valid data?

Bilal,

you might try a larger AWS instance to make sure your are getting 100% of the box; might help some.

Robert

From: freeswitch-users-bounces at lists.freeswitch.org<mailto:freeswitch-users-bounces at lists.freeswitch.org> [mailto:freeswitch-users-bounces at lists.freeswitch.org<mailto:freeswitch-users-bounces at lists.freeswitch.org>] On Behalf Of Michael Jerris
Sent: Friday, April 14, 2017 4:25 PM
To: FreeSWITCH Users Help <freeswitch-users at lists.freeswitch.org<mailto:freeswitch-users at lists.freeswitch.org>>
Subject: Re: [Freeswitch-users] Choppy audio when conferencing 4+ participants

can you reproduce the same issue on real hardware?  We’ve seen all kinds of weird timing issues that could account for this running on aws.

On Apr 14, 2017, at 4:16 PM, Bilal Dar <bilal at rgate-systems.com<mailto:bilal at rgate-systems.com>> wrote:

Its an AWS m3.2xlarge instance.

On Fri, Apr 14, 2017 at 9:57 AM, Michael Jerris <mike at jerris.com<mailto:mike at jerris.com>> wrote:
Real hardware or VM?

> On Apr 14, 2017, at 12:48 PM, Bilal Dar <bilal at rgate-systems.com<mailto:bilal at rgate-systems.com>> wrote:
>
> I have been struggling with an issue for almost 2 weeks.
>
> Our regular calls have no quality issue and looking RTCP statistics network conditions are perfect. We have normally on peak hr 60 calls and around 10 conferences.
>
> We have noticed that when we have 2 conferences of 4 or 5 participants, audio starts breaking for the users who are on conference. Regular calls do not experience any quality degradation.
>
> I upgraded the server to specs of 30Gig memory and 8 vCPU but still the issue exists. Common thing I have noticed even during off-peak hrs is that two 4+ participant call can cause the issue.
>
> I have ruled out network & hardware. Last change I made was moved all users to G.711 from G.722. Now I am not sure what other steps I can take. Appreciate any suggestions.


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