Wireshark · Wireshark-users: Re: [Wireshark-users] skew, delta and jitter in wireshark VOIP->analyse

[nangergong <nangergong@xxxxxxxxx>]

Maybe I need to add:

when I use G711 or G729, wireshark can show the jitter/skew/delta

and if I use iLBC, wireshark can show the codec name (iLBC) bandwidth, packet loss, but  skew, delta and jitter shown in wireshark VOIP-Analysis GUI are 
all 0

On Wed, Feb 9, 2011 at 5:30 PM, Anders Broman <anders.broman@xxxxxxxxxxxx> wrote:

Hi,

It might depend on the version you are using, the RTP analysis needs to know the sampling rate (8KHz normally for voice) and the sampling

rate is only known for the fixed payload types and a set of dynamic ones(hard coded list), in newer WS versions the sampling rate is extracted from SDP.

I don't remember if it's part of 1.4.x or if you have to use a development version.

Regards

Anders

---

From: wireshark-users-bounces@xxxxxxxxxxxxx [mailto:wireshark-users-bounces@xxxxxxxxxxxxx] On Behalf Of nangergong
Sent: den 9 februari 2011 17:37
To: Community support list for Wireshark

Subject: Re: [Wireshark-users] skew, delta and jitter in wireshark VOIP->analyse

thanks

BTW, when I use iLBC codec for audio VOIP calls, I noticed that the skew, delta and jitter shown in wireshark VOIP-Analysis GUI are all 0, what is the reason for this? Does this mean that wireshark can't analyze iLBC codec?

On Wed, Feb 9, 2011 at 2:04 PM, Anders Broman <anders.broman@xxxxxxxxxxxx> wrote:

-----Original Message-----
From: wireshark-users-bounces@xxxxxxxxxxxxx [mailto:wireshark-users-bounces@xxxxxxxxxxxxx] On Behalf Of Giles Coochey
Sent: den 9 februari 2011 14:48
To: wireshark-users@xxxxxxxxxxxxx
Subject: Re: [Wireshark-users] skew, delta and jitter in wireshark VOIP->analyse

On 09/02/2011 14:37, nangergong wrote:
>> Hi, all,
>>
>>   What is the difference between skew, delta and jitter in a voip stream?
>>
>>   I only know the impact of jitters on voip streams, what are the
>> impacts of skew and delta on VOIP streaming quality?
>>
>>   Thank you!
>Not sure if my understanding is correct... skew is absolute jitter based on comparison on the first packet(s).
>delta is what I understand to be latency, or delay.
>
>--
>Best Regards,
>
>Giles Coochey

See http://books.google.com/books?id=OM7YJAy9_m8C&pg=PA175&lpg=PA175&dq=RTP+skew&source=bl&ots=hUOESKrWB4&sig=F2cjXTyonrfi5R7pgKjuHRli4SA&hl=sv&ei=np1STe-PFIfLswbL7bjyBg&sa=X&oi=book_result&ct=result&resnum=10&ved=0CEQQ6AEwCQ#v=onepage&q=RTP%20skew&f=false




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