Wireshark-users: Re: [Wireshark-users] Jitter wrong in wireshark?
From: "Anders Broman" <[email protected]>
Date: Mon, 26 Feb 2007 21:03:48 +0100
Hi,
I've added a note on RTP timestamp, please review.
Best regards
Anders

-----Ursprungligt meddelande-----
Från: [email protected]
[mailto:[email protected]] För Lars Ruoff
Skickat: den 26 februari 2007 14:46
Till: Community support list for Wireshark
Ämne: Re: [Wireshark-users] Jitter wrong in wireshark?

Hi Anders,
since this too is a recurring question, perhaps you (or someone else) could
add it to the Wiki, just under what i added last week:
http://wiki.wireshark.org/RTP_statistics (bottom).
(I'm sorry, i don't have the time right now).

br,
Lars


Anders Broman wrote:
> Hi,
> Looking at the sources there is code there to use different frequencies
> But for dynamic payload types there are two prerequisites that must be
met:
> - The setup signalling must be in the traces for Wireshark to track the
> PT to the media type.
> - The media type sampling frequency must be in the table of rtp_analysis.c
> 
> This types are currently specified:
> static const mimetype_and_clock mimetype_and_clock_map[] = {
> 	{"AMR",		8000},  /* [RFC3267] */
> 	{"AMR-WB",	16000},  /* [RFC3267] */
> 	{"EVRC",	8000},  /* [RFC3558] */
> 	{"EVRC0",	8000},  /* [RFC3558] */
> 	{"G7221",	16000},  /* [RFC3047] */
> 	{"G726-16",	8000},  /* [RFC3551] */
> 	{"G726-24",	8000},  /* [RFC3551] */
> 	{"G726-32",	8000},  /* [RFC3551] */
> 	{"G726-40",	8000},  /* [RFC3551] */
> 	{"G729D",	8000},  /* [RFC3551] */
> 	{"G729E",	8000},  /* [RFC3551] */
> 	{"GSM-EFR",	8000},  /* [RFC3551] */
> 	{"mpa-robust",	90000},  /* [RFC3119] */
> 	{"SMV",		8000},  /* [RFC3558] */
> 	{"SMV0",	8000},  /* [RFC3558] */
> 	{"red",		1000},  /* [RFC4102] */
> 	{"t140",		1000},  /* [RFC4103] */
> 	{"BMPEG",	90000},  /* [RFC2343],[RFC3555] */
> 	{"BT656",	90000},  /* [RFC2431],[RFC3555] */
> 	{"DV",		90000},  /* [RFC3189] */
> 	{"H263-1998",	90000},  /* [RFC2429],[RFC3555] */
> 	{"H263-2000",	90000},  /* [RFC2429],[RFC3555] */
> 	{"MP1S",	90000},  /* [RFC2250],[RFC3555] */
> 	{"MP2P",	90000},  /* [RFC2250],[RFC3555] */
> 	{"MP4V-ES",	90000},  /* [RFC3016] */
> 	{"pointer",	90000},  /* [RFC2862] */
> 	{"raw",		90000},  /* [RFC4175] */
> };
> Best regards
> Anders
> 
> 
> 
> -----Ursprungligt meddelande-----
> Från: [email protected]
> [mailto:[email protected]] För [email protected]
> Skickat: den 24 februari 2007 17:45
> Till: [email protected]
> Ämne: Re: [Wireshark-users] Jitter wrong in wireshark?
> 
> Hi Anders,
> 
> Yes, your are right. Codecs affect jitter calculation because of the
> sampling frequency. In practice, it affects when calculating the timestamp
> to seconds. I.e: when multipling timestamp ticks to convert to seconds one
> must use the frequency sampling of the current codec. As wireshark uses
> always 0.000125 (it looks like this is not configurable), then if codec is
> not G711 calculations will be wrong. 
> 
> And that´s my case :(
> BR
> Juan
> 
> 
> 
> 
> 
> 
>> -----Original Message-----
>> From: [email protected] 
>> [mailto:[email protected]] On Behalf Of 
>> ext Anders Broman
>> Sent: Sábado, 24 de Febrero de 2007 04:50 a.m.
>> To: 'Community support list for Wireshark'
>> Subject: Re: [Wireshark-users] Jitter wrong in wireshark?
>>
>> 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
>>
>> ________________________________________
>> Från: [email protected]
>> [mailto:[email protected]] För 
>> [email protected]
>> Skickat: den 23 februari 2007 18:29
>> Till: [email protected]
>> 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
>>
>> ________________________________________
>> 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 
>> _______________________________________________
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>> [email protected]
>> http://www.wireshark.org/mailman/listinfo/wireshark-users
>>
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