Wireshark-users: [Wireshark-users] Wrong calculation of jitter by wireshark

From: capricorn 80 <cool_capricorn80@xxxxxxxxxxx>
Date: Sat, 15 May 2010 10:32:13 +0000

 Hi!

  I have captured the RTP packets on receiving side and check the values of jitter and than i calculated the values manually and it looks like wire shark is not calculating the values in correct way or may be I am doing some thing wrong. I am pasting all me calculation so that you people can verify it.

Frame 18

Time of Arrival: 29.490533000

Timestamp: 365000

 

Frame 20

Time of Arrival : 29.501315000

Timestamp: 365160

 

D(i,j) = (Rj - Ri) - (Sj - Si) = (Rj - Sj) - (Ri - Si)

J(i) = J(i-1) + (|D(i-1,i)| - J(i-1))/16

D = (29. 501315000- 29. 490533000) � (365160*0.000125 � 365000*0.000125)

    = -0.009218

J = 0 + (|-0.009218| - 0)/16

  = 0.576 msec

 

Frame 22

 

Time of Arrival: 29.520124000

TimeStamp: 365320

 

(29.520124000 - 29.501315000) � (365320*0.000125 � 365160*0.000125)

=-0.001191

J= 0.576+(|-0.001191|-.576)/16

 

J= 0.54             ,

 

Wireshark calculation for frame 22 = 0.61

 

Frame 24

 

Time of Arrival: 29.539717000

Time Stamp: 365480

 

D=(29.539717000 - 29.520124000) � (365480*.000125-365320*.000125)

 

 

D= -0.000407

 

J=0.54+(|-.000407|-.0.54)/16

 

J=0.50

 

Wireshark Calculation for frame 24 = 0.60



Really thanks for your time.



Regards,






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