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RTP Statistics

0

After capturing some RTP traffic i see the following

Now i'm having troubles intepreting the Mean Jitter value. (looked on the forum but not alot info about it)

So three questions


    

  1. Sot he max delta is the time difference between the packets correct?
    2. 

  2. The mean jitter is a calculation between the max delta and max jitter?
    3. 

  3. What is max skew?
    4. 



Thanks in advance!


Sica

asked 09 Apr ‘13, 05:03

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Sicabre
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accept rate: 0%

edited 28 Apr ‘13, 10:41

One Answer:

0

So three questions

Three answers ;-)

  1. The delta is the time difference between the current packet and the previous packet in the stream. max delta is the largest delta value.

  2. Please take a look how Wireshark caluclates the jitter value: http://wiki.wireshark.org/RTP_statistics (search for: How jitter is calculated). The mean jitter value is the arithmetic mean value of all jitter values.

  3. Skew calculation is defined as follows (from: tap-rtp-common.c). max skew is the largest value of all skew values.

        /* Calculate skew, i.e. absolute jitter that also catches clock drift
         * Skew is positive if TS (nominal) is too fast
         */
        statinfo->skew    = nominaltime - arrivaltime;
        absskew = fabs(statinfo->skew);
        if(absskew > fabs(statinfo->max_skew)){
            statinfo->max_skew = statinfo->skew;
        }

Regards
Kurt

answered 10 Apr '13, 08:16

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Kurt Knochner ♦
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accept rate: 15%

Hey Kurt,

Thanks for your reply. So if mean(average) is 2 ms this imply's that the average jitter during the whole rtp call is 2ms with (somewhere during the call) was 5000ms?

Sica

(11 Apr '13, 07:38) Sicabre

Yes.

Kurt

(11 Apr '13, 07:45) Kurt Knochner ♦