Re: [Ekiga-list] Echo in Calls
- From: Shawn Adams <shawn_adams web de>
- To: Ekiga mailing list <ekiga-list gnome org>
- Subject: Re: [Ekiga-list] Echo in Calls
- Date: Wed, 08 Apr 2009 23:46:19 +0200
I think you've all but proven the issue, if the hard phone works - same
server, same internet connection, same everything - except - the phone
itself (replaced Ekiga with this phone temporarily) and there is no
delay - thus - no echo, the PC is the issue.
Exactly how to track the delay inside the PC from mike/speaker through
ekiga to the network card - I'll have to defer to the SW guys. I use
lots of older PCs with ancient sound cards, and these usually are a
likely source of latency.
At least you can check the PC->server or PC->PC latency - a simple test
is ping - see what the maximum and average , example, send 5 frames:
sadams tau:~> ping -c 5 ekiga.net
PING ekiga.net (184.108.40.206) 56(84) bytes of data.
64 bytes from ekiga.net (220.127.116.11): icmp_seq=1 ttl=56 time=34.4 ms
64 bytes from ekiga.net (18.104.22.168): icmp_seq=2 ttl=56 time=96.4 ms
64 bytes from ekiga.net (22.214.171.124): icmp_seq=3 ttl=56 time=34.1 ms
64 bytes from ekiga.net (126.96.36.199): icmp_seq=4 ttl=56 time=34.7 ms
64 bytes from ekiga.net (188.8.131.52): icmp_seq=5 ttl=56 time=43.0 ms
--- ekiga.net ping statistics ---
5 packets transmitted, 5 received, 0% packet loss, time 4001ms
rtt min/avg/max/mdev = 34.106/48.542/96.460/24.190 ms
check to see if the PC network card has errors:
ethtool -S eth0 /mii-diag (depends on card/distro)
Note the max and average delay. anything over approx. 25ms - You have a
chance of hearing the echo. Now how to do this between application and
network interface - I'll have to pass.
Hope this helps.
Robert Ingraham wrote:
> After fiddling around a little bit, I think the real problem is not so
> much echo as latency, and I think the problem is probably with the
> Ekiga/Jaunty combination. I set the system audio settings and the
> Ekiga audio settings both to the same thing, in this case to
> Nvidia/Alsa (my sound card is Nvidia), and I lowered the jitter buffer
> from 500 (the default) to 220. This eliminated a lot (not all) of the
> echo. If I lower the jitter buffer any more, the calls begin to break
> up. However, there is still a very bad latency (delay) problem. Very bad.
> As a test, I unplugged my laptop from the ethernet wire, and plugged
> the same ethernet wire into a VOIP hard phone, configured to use the
> same server. On the VOIP hard phone, there is no echo, no delay, and
> the calls are clear. No noticible latency problem at all.
> I should mention that I used Ekiga under Ubuntu Intrepid, and I did
> not have the Latency/Echo problems. It only started after I upgraded
> to Jaunty beta. Any thoughts?
> On Sat, Apr 4, 2009 at 3:06 AM, Shawn Adams <shawn_adams web de
> <mailto:shawn_adams web de>> wrote:
> It's not a bandwidth issue.
> There are two main sources of echo in telephony networks: acoustic
> and line echo. Acoustic echo is generated on any phone (IP phone or
> analog) when there is feedback from the speaker to the microphone.
> This is particularly noticeable on many speaker phones. Line echo is
> very common in the PSTN network, and this most commonly occurs when
> there is a two-wire to four-wire conversion in the network (for
> where analog is converted into T1 or E1). In the good old telephone
> network, the delay is so small, the human ear doesn't notice.
> They have also 50+ years experience with echo cancellation, which
> well on analog signals, but is more difficult with VOIP.
> Leak-through happens only in analog circuits. VOIP frames do not leak.
> Echo is almost always happening at the opposite end of where the
> echo is
> perceived. It might be happening at the PSTN gateway as well.
> If you've set your mute button, but the other side still hears
> echo, it
> is possibly a leak in your VOIP phone or sound card/drivers area,
> or the
> The gateway to the PSTN is just another source of delay, they more
> - the more perceptable the echo.
> #1 does a purely SIP/VOIP call have the echo ?
> - if NO - the echo may be induced at the PSTN gateway, in each case,
> check the round trip delay between your phone and the target.
> #2 what is the round trip delay from your phone to the PSTN gateway ?
> - there is almost always echo on a good old fashioned telephone,
> but you
> don't notice it because the delay is <25ms
> - if you can somehow reduce the round trip delay - this might minimize
> the perceived echo, 150ms is usually a good rule-of-thumb as maximum
> tolerable for VOIP calls.
> #3 it is possible the echo is in the sound card/devices/drivers - I've
> had luck playing with volume levels disabling of the various sound
> devices - capture device, PCM volume, etc...
> So see if you can isolate whether the echo is at the gateway, or
> at your
> phone. There may be little you can do about the gateway, except to
> complain to the provider. If it's at the phone - take a look at the
> various devices/pulse audio, etc...
> My 2 cents....
> Hope this helps.
> Best regards,
> Robert Ingraham wrote:
> > I have read previous posts on this subject, but I still cannot
> > the problem. I use Ekiga to make PC-to-Phone calls. I use a headset.
> > I am running Ubuntu Jaunty beta, with PulseAudio. When I make
> calls, I
> > can hear fine, with no echo, but the people I am talking to
> complain of
> > a very bad echo. This includes both landlines and cellphones.
> There is
> > also a delay between when they talk, and when I hear them. The
> > I use has a mute button, but even if I mute my end, the other person
> > still hears an echo. I have tried enabling both "echo
> cancelation" and
> > "silence detection" in Ekiga's preferences, but this has had no
> > at all on the echo. Ekiga's codec preferences are set to use Speex
> > 16khz codec. I have a very good Comcast cable connection, with
> > rates in the 750mb-1gb range. Anyone have any idea how to fix this?
> > Would turning off PulseAudio help?
> > _______________________________________________
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> > ekiga-list gnome org <mailto:ekiga-list gnome org>
> > http://mail.gnome.org/mailman/listinfo/ekiga-list
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