Re: skew, delta and jitter in wireshark VOIP->analyse

[Anders Broman <anders.broman () ericsson com>]

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 () wireshark org [mailto:wireshark-users-bounces () wireshark org] 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 () ericsson com<mailto:anders.broman () ericsson com>> 
wrote:


-----Original Message-----
From: wireshark-users-bounces () wireshark org<mailto:wireshark-users-bounces () wireshark org> 
[mailto:wireshark-users-bounces () wireshark org<mailto:wireshark-users-bounces () wireshark org>] On Behalf Of Giles 
Coochey
Sent: den 9 februari 2011 14:48
To: wireshark-users () wireshark org<mailto:wireshark-users () wireshark org>
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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