[Freeswitch-users] KVM vs. XEN virtualization

Thu Apr 9 18:12:54 MSD 2015

I made 5 calls from each of 3 test servers (KVM at DigitalOcean in
London, Scaleway physical in Paris, and a XEN host at softronics.ch
near Zurich), and the PESQ assessment tool shows varying results: for
each host, the MOS score was fluctuating between 2.5 and 3.8.

So, KVM doesn't seem to be too bad  :-)

On Thu, Apr 9, 2015 at 1:21 PM, Stanislav Sinyagin <ssinyagin at gmail.com> wrote:
> thanks, the PESQ tool appears to be open-source and free for
> non-commercial use, so I started a series of tests. I'll post an
> update.
> http://www.itu.int/rec/T-REC-P.862-200511-I!Amd2/en
>
>
>
> On Thu, Apr 9, 2015 at 12:36 PM, Jayanth Acharya <jayachar88 at gmail.com> wrote:
>> 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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>>> >>>>>
>>> >>>>>
>>> >>>>>
>>> >>>>>
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>>> >>>>
>>> >>>>
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>>> >>>>
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>>> >>>
>>> >>>
>>> >>>
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>>> >>>
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>>
>>
>>
>> _________________________________________________________________________
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>>
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