<div dir="ltr"><div><div><div>Good job and Thanks for sharing!<br></div><div><br><blockquote style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex" class="gmail_quote">KVM at <span class=""><a href="http://digitalocean.com">digitalocean.com</a></span>, Debian 7 64bit, FreeSWITCH 1.4.15: <span style="color:rgb(255,0,0)">bad precision</span></blockquote><div> </div></div>As someone who has been using KVM for a few years and has just migrated about 20 VMs across to Digital Ocean about 6 weeks ago I admit I am a little concerned about this finding.<br><br></div>Just out of curiosity can you tell me the specs of the VM that you tested with and which DO Datacenter? I am using NYC3 so perhaps and I will do some tests as soon as I have some time.<br><br></div>With regards to Xen was this at Linode or inhouse?<br><br><div>Thanks<br><br></div><div>Errol<br><br></div><div><br></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Sun, Apr 5, 2015 at 1:37 AM, Stanislav Sinyagin <span dir="ltr"><<a href="mailto:ssinyagin@gmail.com" target="_blank">ssinyagin@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">here we go:<br>
<a href="https://txlab.wordpress.com/2015/04/05/testing-rtp-clock-precision-on-a-virtual-machine/" target="_blank">https://txlab.wordpress.com/2015/04/05/testing-rtp-clock-precision-on-a-virtual-machine/</a><br>
<div class="HOEnZb"><div class="h5"><br>
<br>
<br>
On Sat, Apr 4, 2015 at 4:26 PM, Stanislav Sinyagin <<a href="mailto:ssinyagin@gmail.com">ssinyagin@gmail.com</a>> wrote:<br>
> On Sat, Apr 4, 2015 at 1:03 PM, Regis M <<a href="mailto:regis.freeswitch.org@tornad.net">regis.freeswitch.org@tornad.net</a>> wrote:<br>
>> How do you check wavs together in audacity ?<br>
><br>
> you just open two WAV files, align their starting position, and<br>
> visually check the waves. If there's a problem, you would see that<br>
> after few seconds, the waves are not aligned any more.<br>
><br>
>> Can you send me 2 samples wav (send... and recorded) so I could see the 20ms<br>
>> diff that you exposed...<br>
>><br>
>> Is there a way to automate the result checking, so it could help to monitor<br>
>> itsp quality<br>
><br>
> Here<br>
> <a href="https://github.com/openpreserve/scape-xcorrsound/issues/17" target="_blank">https://github.com/openpreserve/scape-xcorrsound/issues/17</a><br>
> this is a link to a tool which compares two sound files at the wave<br>
> level. You can also see the sound samples in the ticket.<br>
> The problem is, that currently this tool does not detect such slipping frames.<br>
><br>
> I will also write a detailed article with examples, during the weekend.<br>
><br>
><br>
><br>
><br>
><br>
>><br>
>><br>
>> 2015-04-04 12:53 GMT+02:00 Stanislav Sinyagin <<a href="mailto:ssinyagin@gmail.com">ssinyagin@gmail.com</a>>:<br>
>>><br>
>>> Important is to send the media through two independent carriers - then you<br>
>>> can be sure that your clock is compared against a high quality one.<br>
>>><br>
>>> On Apr 4, 2015 12:46 PM, "Regis M" <<a href="mailto:regis.freeswitch.org@tornad.net">regis.freeswitch.org@tornad.net</a>><br>
>>> wrote:<br>
>>>><br>
>>>> Hi,<br>
>>>><br>
>>>> It's a very interresting test and conclusion.<br>
>>>><br>
>>>> I will try to build a similar environnement on my freeswitch to check<br>
>>>> some system :)<br>
>>>><br>
>>>> thanks<br>
>>>><br>
>>>><br>
>>>><br>
>>>> 2015-04-04 2:16 GMT+02:00 Stanislav Sinyagin <<a href="mailto:ssinyagin@gmail.com">ssinyagin@gmail.com</a>>:<br>
>>>>><br>
>>>>> hi,<br>
>>>>><br>
>>>>> Here are some test results which might be interesting:<br>
>>>>><br>
>>>>> I've set up a test FreeSWITCH server at digitalocean (they use KVM),<br>
>>>>> and originated test calls to some ITSP accounts. Each call played a<br>
>>>>> test sound file (voice samples from ITU:<br>
>>>>> <a href="http://www.itu.int/net/itu-t/sigdb/genaudio/AudioForm-g.aspx?val=1000050" target="_blank">http://www.itu.int/net/itu-t/sigdb/genaudio/AudioForm-g.aspx?val=1000050</a><br>
>>>>> ), and on the receiving end another FreeSWITCH server was recording<br>
>>>>> the received session. The receiving server was on a XEN VM. Both<br>
>>>>> servers talked G711 to their corresponding ITSP accounts.<br>
>>>>><br>
>>>>> Then I compared the source audio and received audio in Audacity editor.<br>
>>>>><br>
>>>>> The tests showed that the received voice wave shifts 20ms from the<br>
>>>>> original sound every few seconds, randomly back and forward. This<br>
>>>>> skewing was always present, regardless of ITSP and time of day.<br>
>>>>><br>
>>>>> Then I moved the sending server to a XEN VM, and the waves appeared<br>
>>>>> almost perfectly synchronized (there was a 5ms skew in one test, and I<br>
>>>>> guess it's related to transcoding buffer, as the sound was obviously<br>
>>>>> transcoded).<br>
>>>>><br>
>>>>> The effect was always visible with a 30-second sample, and I also made<br>
>>>>> additional tests with 2-minute samples.<br>
>>>>><br>
>>>>> It would also be interesting to test this from a VmWare VM. If someone<br>
>>>>> wants to run such a test, feel free to contact me directly.<br>
>>>>><br>
>>>>><br>
>>>>> cheers,<br>
>>>>> stan<br>
>>>>><br>
>>>>><br>
>>>>> _________________________________________________________________________<br>
>>>>> Professional FreeSWITCH Consulting Services:<br>
>>>>> <a href="mailto:consulting@freeswitch.org">consulting@freeswitch.org</a><br>
>>>>> <a href="http://www.freeswitchsolutions.com" target="_blank">http://www.freeswitchsolutions.com</a><br>
>>>>><br>
>>>>> Official FreeSWITCH Sites<br>
>>>>> <a href="http://www.freeswitch.org" target="_blank">http://www.freeswitch.org</a><br>
>>>>> <a href="http://confluence.freeswitch.org" target="_blank">http://confluence.freeswitch.org</a><br>
>>>>> <a href="http://www.cluecon.com" target="_blank">http://www.cluecon.com</a><br>
>>>>><br>
>>>>> FreeSWITCH-users mailing list<br>
>>>>> <a href="mailto:FreeSWITCH-users@lists.freeswitch.org">FreeSWITCH-users@lists.freeswitch.org</a><br>
>>>>> <a href="http://lists.freeswitch.org/mailman/listinfo/freeswitch-users" target="_blank">http://lists.freeswitch.org/mailman/listinfo/freeswitch-users</a><br>
>>>>> UNSUBSCRIBE:<a href="http://lists.freeswitch.org/mailman/options/freeswitch-users" target="_blank">http://lists.freeswitch.org/mailman/options/freeswitch-users</a><br>
>>>>> <a href="http://www.freeswitch.org" target="_blank">http://www.freeswitch.org</a><br>
>>>><br>
>>>><br>
>>>><br>
>>>> _________________________________________________________________________<br>
>>>> Professional FreeSWITCH Consulting Services:<br>
>>>> <a href="mailto:consulting@freeswitch.org">consulting@freeswitch.org</a><br>
>>>> <a href="http://www.freeswitchsolutions.com" target="_blank">http://www.freeswitchsolutions.com</a><br>
>>>><br>
>>>> Official FreeSWITCH Sites<br>
>>>> <a href="http://www.freeswitch.org" target="_blank">http://www.freeswitch.org</a><br>
>>>> <a href="http://confluence.freeswitch.org" target="_blank">http://confluence.freeswitch.org</a><br>
>>>> <a href="http://www.cluecon.com" target="_blank">http://www.cluecon.com</a><br>
>>>><br>
>>>> FreeSWITCH-users mailing list<br>
>>>> <a href="mailto:FreeSWITCH-users@lists.freeswitch.org">FreeSWITCH-users@lists.freeswitch.org</a><br>
>>>> <a href="http://lists.freeswitch.org/mailman/listinfo/freeswitch-users" target="_blank">http://lists.freeswitch.org/mailman/listinfo/freeswitch-users</a><br>
>>>> UNSUBSCRIBE:<a href="http://lists.freeswitch.org/mailman/options/freeswitch-users" target="_blank">http://lists.freeswitch.org/mailman/options/freeswitch-users</a><br>
>>>> <a href="http://www.freeswitch.org" target="_blank">http://www.freeswitch.org</a><br>
>>><br>
>>><br>
>>> _________________________________________________________________________<br>
>>> Professional FreeSWITCH Consulting Services:<br>
>>> <a href="mailto:consulting@freeswitch.org">consulting@freeswitch.org</a><br>
>>> <a href="http://www.freeswitchsolutions.com" target="_blank">http://www.freeswitchsolutions.com</a><br>
>>><br>
>>> Official FreeSWITCH Sites<br>
>>> <a href="http://www.freeswitch.org" target="_blank">http://www.freeswitch.org</a><br>
>>> <a href="http://confluence.freeswitch.org" target="_blank">http://confluence.freeswitch.org</a><br>
>>> <a href="http://www.cluecon.com" target="_blank">http://www.cluecon.com</a><br>
>>><br>
>>> FreeSWITCH-users mailing list<br>
>>> <a href="mailto:FreeSWITCH-users@lists.freeswitch.org">FreeSWITCH-users@lists.freeswitch.org</a><br>
>>> <a href="http://lists.freeswitch.org/mailman/listinfo/freeswitch-users" target="_blank">http://lists.freeswitch.org/mailman/listinfo/freeswitch-users</a><br>
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>>> <a href="http://www.freeswitch.org" target="_blank">http://www.freeswitch.org</a><br>
>><br>
>><br>
>><br>
>> _________________________________________________________________________<br>
>> Professional FreeSWITCH Consulting Services:<br>
>> <a href="mailto:consulting@freeswitch.org">consulting@freeswitch.org</a><br>
>> <a href="http://www.freeswitchsolutions.com" target="_blank">http://www.freeswitchsolutions.com</a><br>
>><br>
>> Official FreeSWITCH Sites<br>
>> <a href="http://www.freeswitch.org" target="_blank">http://www.freeswitch.org</a><br>
>> <a href="http://confluence.freeswitch.org" target="_blank">http://confluence.freeswitch.org</a><br>
>> <a href="http://www.cluecon.com" target="_blank">http://www.cluecon.com</a><br>
>><br>
>> FreeSWITCH-users mailing list<br>
>> <a href="mailto:FreeSWITCH-users@lists.freeswitch.org">FreeSWITCH-users@lists.freeswitch.org</a><br>
>> <a href="http://lists.freeswitch.org/mailman/listinfo/freeswitch-users" target="_blank">http://lists.freeswitch.org/mailman/listinfo/freeswitch-users</a><br>
>> UNSUBSCRIBE:<a href="http://lists.freeswitch.org/mailman/options/freeswitch-users" target="_blank">http://lists.freeswitch.org/mailman/options/freeswitch-users</a><br>
>> <a href="http://www.freeswitch.org" target="_blank">http://www.freeswitch.org</a><br>
<br>
_________________________________________________________________________<br>
Professional FreeSWITCH Consulting Services:<br>
<a href="mailto:consulting@freeswitch.org">consulting@freeswitch.org</a><br>
<a href="http://www.freeswitchsolutions.com" target="_blank">http://www.freeswitchsolutions.com</a><br>
<br>
Official FreeSWITCH Sites<br>
<a href="http://www.freeswitch.org" target="_blank">http://www.freeswitch.org</a><br>
<a href="http://confluence.freeswitch.org" target="_blank">http://confluence.freeswitch.org</a><br>
<a href="http://www.cluecon.com" target="_blank">http://www.cluecon.com</a><br>
<br>
FreeSWITCH-users mailing list<br>
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</div></div></blockquote></div><br></div>