[Freeswitch-users] Long increasing audio delay

[Ciprian Dosoftei]

The long story short is: the more you separate a real-time application from
the metal, the worse it gets. WSL does implement most (if not all) Linux
kernel syscalls but ultimately translates into NT kernel specific
implementations which will inherently induce some additional delay.

KVM/Xen are reasonably good in terms of providing good timers for real-time
applications, but even then, the difference compared against metal is
noticeable, however, less of an issue for reasonable volume as well as
other circumstances (primarily, if trans-coding is involved).

Debian on metal is your best choice, though it should not be a
showstopper over Xen or KVM if your circumstances are not too demanding.

On Thu, 5 Dec 2019 at 14:35, Jaan Kaja <Jaan.Kaja at enghouse.com> wrote:

> Hello,
>
>
>
> We are testing webrtc via mod_verto with the verto_communicator demo.
> After some initial troubles with certificates, we have it running from
> Chrome and Firefox. Very nice!
>
>
>
> But, when we leave the connection on for some time, the audio in the
> direction from the browser to a phone becomes increasingly longer. We have
> clocked ~11 seconds, if we leave it on long enough. The audio in the other
> direction has a normal IP telephony delay. We have not found any browser
> dependencies.
>
>
>
> The FreeSWITCH version is 1.10.1 (latest stable release). The phone end
> has been a Blink softphone, or a trunk from a Cisco UCM. The latter
> negotiated mulaw PCM with a 20 ms packet size.
>
>
>
> We have tried different server OS:es:
>
> ·         Windows Server 2019 gives the fastest buildup of delay.
>
> ·         Debian installed in a Windows Substrate for Linux gives a
> slower buildup of delay, but it does continuously increase.
>
> ·         CentOS virtualized in VMWare doesn’t have any buildup of delay,
> and the delay is a normal IP telephony delay.
>
> ·         So, the more Windows, the worse…
>
>
>
> I have a Wireshark trace, and I can get a TLS stream from it. I can
> install a key file to decode the stream, but the configuration wants a
> protocol, and I don’t know what to enter there. There are no dissectors for
> Websocket. So I’m at a bit of a loss, as to how to debug this. I don’t see
> anything obvious in the freeswitch.log.
>
>
>
> Questions:
>
> ·         Has anyone used webrtc on Windows?
>
> ·         Has anyone had the same problem?
>
> ·         What can be done to debug the problem? Turn on some logging?
>
>
>
> We could package a Linux machine to our customers, but as everything else
> is on Windows, it would be nice to make it work.
>
>
>
> Best regards,
>
> Jaan
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-- 
Best Regards,
Ciprian Dosoftei

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