[Freeswitch-users] KVM vs. XEN virtualization

[Jayanth Acharya]

See if this helps -
http://www.voip-info.org/wiki/view/Call+Quality+Metrics
http://www.tamos.com/htmlhelp/voip-analysis/mosandr_factor.htm


On Thu, Apr 9, 2015 at 3:18 PM, Stanislav Sinyagin <ssinyagin at gmail.com>
wrote:

> I made additional tests, and... I'm not sure any more. So, I removed
> the statement about bad precision. This needs a lab environment with
> predictable network and known CPU load on the host machine.
>
> Does anyone know any tools that would automatically detect sound
> distortions in WAV files and also find the shifts because of slipping
> clock or lost frames?  Up to now, the only tool I could find is
> visually comparing the waves in Audacity.
>
>
>
> On Sun, Apr 5, 2015 at 2:37 AM, Stanislav Sinyagin <ssinyagin at gmail.com>
> wrote:
> > here we go:
> >
> https://txlab.wordpress.com/2015/04/05/testing-rtp-clock-precision-on-a-virtual-machine/
> >
> >
> >
> > On Sat, Apr 4, 2015 at 4:26 PM, Stanislav Sinyagin <ssinyagin at gmail.com>
> wrote:
> >> On Sat, Apr 4, 2015 at 1:03 PM, Regis M <
> regis.freeswitch.org at tornad.net> wrote:
> >>> How do you check wavs together in audacity ?
> >>
> >> you just open two WAV files, align their starting position, and
> >> visually check the waves. If there's a problem, you would see that
> >> after few seconds, the waves are not aligned any more.
> >>
> >>> Can you send me 2 samples wav (send... and recorded) so I could see
> the 20ms
> >>> diff that you exposed...
> >>>
> >>> Is there a way to automate the result checking, so it could help to
> monitor
> >>> itsp quality
> >>
> >> Here
> >> https://github.com/openpreserve/scape-xcorrsound/issues/17
> >> this is a link to a tool which compares two sound files at the wave
> >> level. You can also see the sound samples in the ticket.
> >> The problem is, that currently this tool does not detect such slipping
> frames.
> >>
> >> I will also write a detailed article with examples, during the weekend.
> >>
> >>
> >>
> >>
> >>
> >>>
> >>>
> >>> 2015-04-04 12:53 GMT+02:00 Stanislav Sinyagin <ssinyagin at gmail.com>:
> >>>>
> >>>> Important is to send the media through two independent carriers -
> then you
> >>>> can be sure that your clock is compared against a high quality one.
> >>>>
> >>>> On Apr 4, 2015 12:46 PM, "Regis M" <regis.freeswitch.org at tornad.net>
> >>>> wrote:
> >>>>>
> >>>>> Hi,
> >>>>>
> >>>>> It's a very interresting test and conclusion.
> >>>>>
> >>>>> I will try to build a similar environnement on my freeswitch to check
> >>>>> some system :)
> >>>>>
> >>>>> thanks
> >>>>>
> >>>>>
> >>>>>
> >>>>> 2015-04-04 2:16 GMT+02:00 Stanislav Sinyagin <ssinyagin at gmail.com>:
> >>>>>>
> >>>>>> hi,
> >>>>>>
> >>>>>> Here are some test results which might be interesting:
> >>>>>>
> >>>>>> I've set up a test FreeSWITCH server at digitalocean (they use KVM),
> >>>>>> and originated test calls to some ITSP accounts. Each call played a
> >>>>>> test sound file (voice samples from ITU:
> >>>>>>
> http://www.itu.int/net/itu-t/sigdb/genaudio/AudioForm-g.aspx?val=1000050
> >>>>>> ), and on the receiving end another FreeSWITCH server was recording
> >>>>>> the received session. The receiving server was on a XEN VM. Both
> >>>>>> servers talked G711 to their corresponding ITSP accounts.
> >>>>>>
> >>>>>> Then I compared the source audio and received audio in Audacity
> editor.
> >>>>>>
> >>>>>> The tests showed that the received voice wave shifts 20ms from the
> >>>>>> original sound every few seconds, randomly back and forward. This
> >>>>>> skewing was always present, regardless of ITSP and time of day.
> >>>>>>
> >>>>>> Then I moved the sending server to a XEN VM, and the waves appeared
> >>>>>> almost perfectly synchronized (there was a 5ms skew in one test,
> and I
> >>>>>> guess it's related to transcoding buffer, as the sound was obviously
> >>>>>> transcoded).
> >>>>>>
> >>>>>> The effect was always visible with a 30-second sample, and I also
> made
> >>>>>> additional tests with 2-minute samples.
> >>>>>>
> >>>>>> It would also be interesting to test this from a VmWare VM. If
> someone
> >>>>>> wants to run such a test, feel free to contact me directly.
> >>>>>>
> >>>>>>
> >>>>>> cheers,
> >>>>>> stan
> >>>>>>
> >>>>>>
> >>>>>>
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