Ethereal-users: [Ethereal-users] Jitter validity

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From: "Szymon Fedor " <szymon.fedor@xxxxxxxxxxxx>
Date: Fri, 30 Apr 2004 13:12:15 GMT
Hello,

I would like to analyse the RTP protocol with Ethereal, especially I am
concerned about the Jitter calculation. Below is the example of a RTP statistic
displayed with Ehereal.

Packet Sequence Delay      Jitter
106    39378    0          0
107    39379    0.002983   0.001689
108    39380    0.006785   0.003034
109    39381    0.003869   0.004478
110    39382    0.004391   0.005798


As I read on the mailing list, the Jitter is calculated with the following
formula:
J = J + ( | D(i-1, i) | - J) / 16
where J is jitter and D is delay between two frames

If I apply this formula to the sequence above I don't get wright result
(for example: 0.001689+(0.006785-0.001689)/16=0.0020075<>0.003034)

Do you know where is the problem? Do you really use the above formula to
calculate the Jitter or I just apply it in a wrong way?

Thank's for the answers

regards
Simon

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