asterisk users - Mar 2010 - Calculating R Factor and MOS metrics for VoIP

Hello All,



MOS and R factor are the two QoS parameters used to estimate VoIP call
quality.


I have found that they are calculated from other metrics like jitter,
latency, packet loss,...etc. But, haven't found any formula or arithmetic
rule to calculate them.



Do you have an idea about their formulas or an open source that calculates
them. Is it possible to interpret them from wireshark.



Thanks.





-- 
Please discover scientific miracles of CORAN

http://www.55a.net/
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Take a look at http://dev.leurent.eu/voip/MOS/
I'v done this a long time ago, hope it will help!
++

Le 08.03.2010 11:10, mosbah.abdelkader a ?crit :
> Hello All,
>
>
>
> MOS and R factor are the two QoS parameters used to estimate VoIP call
> quality.
>
>
> I have found that they are calculated from other metrics like jitter,
> latency, packet loss,...etc. But, haven't found any formula or
> arithmetic rule to calculate them.
>
>
>
> Do you have an idea about their formulas or an open source that
> calculates them. Is it possible to interpret them from wireshark.
>
>
>
> Thanks.
>
>
>
>
>
> -- 
> Please discover scientific miracles of CORAN
>
> http://www.55a.net/

Am 08.03.2010 11:10, schrieb mosbah.abdelkader:
> Hello All,
>
>
>
> MOS and R factor are the two QoS parameters used to estimate VoIP call
> quality.
>
>
> I have found that they are calculated from other metrics like jitter,
> latency, packet loss,...etc. But, haven't found any formula or
> arithmetic rule to calculate them.
IMO most of these calculations are crap, because you can not tell the 
voice quality just based on network statistics.

The perceived quality also heavily depends on the playback algorithms, 
e.g. jitter buffer (static? dynamic? size? FFT for faster playback ...) 
and error correction and error concealment.

AFAIK all the available VoIP MOS calculations operate on packet layer, 
thus they do not include the playback characteristics.

regards
klaus
>
>
>
> Do you have an idea about their formulas or an open source that
> calculates them. Is it possible to interpret them from wireshark.
>
>
>
> Thanks.
>
>
>
>
>
> --
> Please discover scientific miracles of CORAN
>
> http://www.55a.net/
>

On 03/08/2010 06:10 PM, mosbah.abdelkader wrote:
> Hello All,
>
>
>
> MOS and R factor are the two QoS parameters used to estimate VoIP call 
> quality.
You can't calculate MOS. Its an assessment based on a lot of human 
hearing. Nonetheless, there is a profitable industry in pretending to 
calculate MOS.

The definition of the R factor can be found in one of the ITU G series 
specs. I can't remember which one, but it should be easy to
find.
>
> I have found that they are calculated from other metrics like jitter, 
> latency, packet loss,...etc. But, haven't found any formula or 
> arithmetic rule to calculate them.
>
>
>
> Do you have an idea about their formulas or an open source that 
> calculates them. Is it possible to interpret them from wireshark.
>
Steve