Wireshark-users: Re: [Wireshark-users] Jitter wrong in wireshark?
From: "Anders Broman" <[email protected]>
Date: Sat, 24 Feb 2007 08:49:34 +0100
Hi,
If I understood the previous discussion correctly the RTP timestamp which is
based on the sampling frequency
is used in the calculations. If the wrong sampling frequency is used the
calculations will be off.

If a dynamic PT is used (>95) it probably not G711.
Best regards
Anders

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Skickat: den 23 februari 2007 18:29
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Ämne: Re: [Wireshark-users] Jitter wrong in wireshark?

Hi Anders,
good question. I´m not sure but I guess is codec is PCMA G711 8KHz (will
take a look during call setup in a couple of hours).
 
However "Payload type" is 97 (0x61), and wireshark shows it as "Payload
type=Unknown"
 
According to the formula, jitter calculation depends on timestamps and
arrival time differences. I don´t know how codec could affect.
 
BR
Juan
 

________________________________________
From: [email protected]
[mailto:[email protected]] On Behalf Of ext Anders
Broman (AL/EAB)
Sent: Viernes, 23 de Febrero de 2007 01:05 p.m.
To: Community support list for Wireshark
Subject: SV: [Wireshark-users] Jitter wrong in wireshark?
Hi,
Which codec is used?
Best regards
Anders

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Från: [email protected] genom [email protected]
Skickat: fr 2007-02-23 16:53
Till: [email protected]
Ämne: [Wireshark-users] Jitter wrong in wireshark?
Hi All, 
Below is a rtp analysis from a wireshark 0.99.5 capture in a live network. 
Doing by hand jitter calculation it doesn´t match. And of course, if below
data is real it means we are having jitter of more than 1 minute !!
Exampe: first jitter should be 138.90/16 = 8.68125 [ms] and is showing
8803,82 [ms] !!! 
Do someone know what could be wrong or what I´m missing? 
BR 
Juan 

Forward                                                                
Packet  Sequence        Delta (ms)      Jitter (ms)     IP BW (kbps)   
Marker  Status  Date    Length 
1       0       0.00    0.00    1.45            [ Ok ]  02/19/2007
18:44:25.915 231    
2       1       138.90  8803.82 2.90            [ Ok ]  02/19/2007
18:44:26.053 231    
3       2       119.59  17058.61        4.34            [ Ok ]  02/19/2007
18:44:26.173 231    
4       3       139.67  24796.21        5.79            [ Ok ]  02/19/2007
18:44:26.313 231    
5       4       180.22  32047.69        7.24            [ Ok ]  02/19/2007
18:44:26.493 231    
6       5       241.67  38842.10        8.69            [ Ok ]  02/19/2007
18:44:26.735 231    
7       6       96.71   45220.93        10.14           [ Ok ]  02/19/2007
18:44:26.831 231    
8       7       198.41  51194.72        10.14           [ Ok ]  02/19/2007
18:44:27.030 231    
9       8       205.78  56794.69        8.69            [ Ok ]  02/19/2007
18:44:27.235 231    
10      9       193.62  62045.42        8.69            [ Ok ]  02/19/2007
18:44:27.429 231    
11      10      197.77  66967.72        8.69            [ Ok ]  02/19/2007
18:44:27.627 231    
12      11      208.31  71581.72        7.24            [ Ok ]  02/19/2007
18:44:27.835 231    
13      12      190.92  75908.43        8.69            [ Ok ]  02/19/2007
18:44:28.026 231    
14      13      199.23  79964.20        8.69            [ Ok ]  02/19/2007
18:44:28.225 231    
15      14      183.31  83767.48        8.69            [ Ok ]  02/19/2007
18:44:28.409 231    
16      15      200.50  87331.98        8.69            [ Ok ]  02/19/2007
18:44:28.609 231    
17      16      216.07  90672.73        8.69            [ Ok ]  02/19/2007
18:44:28.825 231    
18      17      137.81  93809.57        8.69            [ Ok ]  02/19/2007
18:44:28.963 231    
19      18      139.08  96750.28        8.69            [ Ok ]  02/19/2007
18:44:29.102 231    
20      19      119.60  99508.41        10.14           [ Ok ]  02/19/2007
18:44:29.222 231    
21      20      119.59  102094.16       10.14           [ Ok ]  02/19/2007
18:44:29.341 231    
22      21      119.18  104518.33       10.14           [ Ok ]  02/19/2007
18:44:29.460 231    
23      22      126.80  106790.51       11.58           [ Ok ]  02/19/2007
18:44:29.587 231    
24      23      112.05  108921.60       11.58           [ Ok ]  02/19/2007
18:44:29.699 231    
25      24      145.14  110917.43       11.58           [ Ok ]  02/19/2007
18:44:29.844 231    
26      25      115.57  112790.36       13.03           [ Ok ]  02/19/2007
18:44:29.960 231    
27      26      118.57  114546.05       13.03           [ Ok ]  02/19/2007
18:44:30.079 231    
28      27      139.44  116190.71       13.03           [ Ok ]  02/19/2007
18:44:30.218 231    
29      28      120.40  117733.77       13.03           [ Ok ]  02/19/2007
18:44:30.338 231    
30      29      118.59  119180.49       13.03           [ Ok ]  02/19/2007
18:44:30.457 231    
31      30      120.00  120536.71       13.03           [ Ok ]  02/19/2007
18:44:30.577 231    
32      31      120.23  121808.15       13.03           [ Ok ]  02/19/2007
18:44:30.697 231    
33      32      119.60  123000.17       13.03           [ Ok ]  02/19/2007
18:44:30.817 231    
34      33      118.72  124117.74       13.03           [ Ok ]  02/19/2007
18:44:30.936 231    
35      34      119.88  125165.39       13.03           [ Ok ]  02/19/2007
18:44:31.055 231    
36      35      146.42  126145.90       13.03           [ Ok ]  02/19/2007
18:44:31.202 231    
37      36      57.34   118265.37       11.90   SET     Incorrect
timestamp     02/19/2007 18:44:31.259 90     
                                                                       
Reverse                                                                
Packet  Sequence        Delta (ms)      Jitter (ms)     IP BW (kbps)   
Marker  Status  Date    Length 
44      1       0.00    0.00    1.45            [ Ok ]  02/19/2007
18:44:36.119 231    
46      2       126.78  99992.08        2.90            [ Ok ]  02/19/2007
18:44:36.246 231    
47      3       293.16  193724.25       4.34            [ Ok ]  02/19/2007
18:44:36.539 231    
48      4       159.97  281606.49       5.79            [ Ok ]  02/19/2007
18:44:36.699 231    
49      5       119.98  363998.58       7.24            [ Ok ]  02/19/2007
18:44:36.819 231    
50      6       160.07  441238.67       8.69            [ Ok ]  02/19/2007
18:44:36.979 231    
51      7       261.00  513644.94       8.69            [ Ok ]  02/19/2007
18:44:37.240 231    
52      8       43.09   481544.82       7.56    SET     Incorrect
timestamp     02/19/2007 18:44:37.283 90