[Asterisk-Users] XTEN-Lite Bad sound!

[Ray Burkholder]

For some of these noise problems, it is good to do a jitter analysis.  I
found it to be the cause of the problems I was having with my Cisco phone
and a X-Lite client.  Also, I found that the X-Pro client is better at voice
delivery than the X-Lite client.

Anyway, if you have tcpdump available on your asterisk server, use it to
collect some timing statistics.

For example,

tcpdump -i eth0 -T rtp dst host x.x.x.x and dst port 8000

(if I have this wrong, 'man tcpdump' will help you with the various
options).

Should decode the rtp stream on eth0 to port 8000 on x-lite. 

Pipe the output to a file.  Should look like:

14:44:43.618422 10.1.1.60.8000 > sip.oneunified.net.15958: udp/rtp 160 c0
4208 758720
14:44:43.619033 10.1.1.60.8000 > sip.oneunified.net.15958: udp/rtp 160 c0
4209 758880
14:44:43.665234 10.1.1.60.8000 > sip.oneunified.net.15958: udp/rtp 160 c0
4210 759040
14:44:43.665521 10.1.1.60.8000 > sip.oneunified.net.15958: udp/rtp 160 c0
4211 759200
14:44:43.665925 10.1.1.60.8000 > sip.oneunified.net.15958: udp/rtp 160 c0
4212 759360

This sample doesn't correspond to the command line shown, but gives you an
idea.

http://www.erg.abdn.ac.uk/users/alastair/tcpdump.html has some descriptive
comments about what you see.

Anyway, now import the file into a spreadsheet.  Do deltas between the times
(first entry on each line, I usually discard the 14:44: stuff and focus on
the nn.nnnnn portion) on each line (line 2 - line 1, line 3 - line 2, ... ).
Make an x-y chart with the numbers in the second last column, 4208, ..., as
x and the deltas as y.

You may find some interesting results in terms of packet delivery timing.
Excellent packet delivery occurs with a max jitter of 20 to 40 ms.  Cisco
phones have a dynamic jitter buffer up to 150 ms.  My problem before was
that an X-Lite softphone on a slow machine or on a really bad internet
connection was averaging jitter between 80 and 200 ms.  It was giving my
phone a really hard time.  Hence the pops and periods of multi second
silence.

This may not be at all useful for your problem, I just used it as an excuse
to update people on my problems.  ;-)

Ray Burkholder
ray at oneunified.net
http://www.oneunified.net
704 576 5101


> -----Original Message-----
> From: asterisk-users-admin at lists.digium.com 
> [mailto:asterisk-users-admin at lists.digium.com] On Behalf Of 
> Jason A. Pattie
> Sent: November 3, 2003 16:49
> To: asterisk-users at lists.digium.com
> Subject: Re: [Asterisk-Users] XTEN-Lite Bad sound!
> 
> 
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
> 
> WipeOut wrote:
> | Has the bad quality started just recently? Has it ever 
> worked nicely for
> | you??
> 
> It depends.  :)
> 
> | If either of these is "yes"..
> |
> | What has changed in your setup? Have you recently upgraded 
> to a  newer
> | CVS??
> 
> I have a fairly recent version of Asterisk, but X-Lite has 
> always worked
> like a charm when accessing the PBX functions directly (i.e., leaving
> voicemail, listening to menus, checking voicemail, etc.).  However,
> whenever I receive or make a call through the X100P card, the 
> people on
> the other end say that I am "garbled" and the audio is very choppy and
> "echo"y.  I also notice an "on again", "off again" kind of 
> "beating" in
> the audio stream whenever I am making a call.  There is a period of
> exactly 4 beats that seem to be more or less the same volume, very low
> and in the background, that span approximately less than a 2 second
> period.  Then there is a period of silence for less than 2 
> seconds, and
> then the cycle is repeated.
> 
> | I don't have an answer for you but at least it may stop 
> others falling
> | into the same problem if somthing can be identified as the cause..
> |
> | later..
> 
> Thanks.
> 
> - --
> Jason A. Pattie
> pattieja at xperienceinc.com
> Xperience, Inc. (http://www.xperienceinc.com)
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