On Sun, 22 Nov 2009, capricorn 80 wrote:
> I am looking to calculate the end-to-end delay between two soft
> phone/hard phone. I have asterisk server and configured ntp server on
> the same machine and synchronized it with ntp pool. I have seen that
> Wireshark can be used to check the jitter. But I am not sure how can i
> calculate the end to end. May be this is not related to the mailing list
> topic but please help me if anyone has some information.
A very long time ago, I made the mistake of letting a client listen (with
a handset on each side of his head) to end-to-end delay.
This all of a sudden became a quest for the Holy Grail to quantify and
reduce the delay.
I got a couple of RadioShack telephone recording interfaces, connected one
to each endpoint. Then I connected the outputs to the left and right
channels on a PC and recorded "tapping" on one of the handsets using
Audacity. When I selected the interval between the "tap" and the
"ping,"
Audacity would show the time in ms.
All very "old-school" but it worked and the client never questioned
the
"pretty pictures" on the computer screen.
Wireshark may be able to tell you how long it takes a packet to travel
across your network, but what about the time from the network interface on
the host until sound comes out the earpiece? How long does it take a SIP
phone to take a packet off it's network interface, wiggle it through
it's
jitter buffer, transcode it, convert it to analog and deliver it to the
earpiece?
--
Thanks in advance,
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Steve Edwards sedwards at sedwards.com Voice: +1-760-468-3867 PST
Newline Fax: +1-760-731-3000