[Freeswitch-users] Removing echo.

Tue Mar 19 21:27:27 MSK 2013

Before the thread dies I would like to add to this subject that there is an
Open Source echo canceler exists: Oslec
As written on their site it already works with "*You*-*Know-Who*"... :)
Has anyone seriously considered integrating it into FreeSWITCH?

2013/3/19 Sean Devoy <sdevoy at bizfocused.com>

> Anthony and Spencer,****
>
> ** **
>
> Thanks for your responses. Anthony the megaphone analogy really worked for
> me.  Spencer thanks for saving me the time of looking up those settings.**
> **
>
> ** **
>
> I agree cell phones frequently have huge echo.  The longer the echo delay
> (aka higher latency) the harder it is to correct makes perfect sense as
> well.****
>
> ** **
>
> I actually had a chance to talk to one of the users experiencing this
> problem.  Bear in mind I usually get to talk to her boss who is looking for
> reasons to not pay his bill.  She said they do still “occasionally” get
> echo but it is not too bad.  She said it is always worse when the call
> certain people (that correlate’s with end user device problems).  Then she
> mentioned I was one of the ones they usually get echo with and it was
> happening now, but not that bad!****
>
> ** **
>
> Opportunity knocked, so I jumped in!  First a quick note of reference – I
> have moderately high hearing loss and wear hearing aids.  I keep my headset
> turned up fairly high!  I asked the user who called me to talk to herself
> while I did some tests and tell me if the echo got better or even went
> away. Low and Behold – mute made it go away COMPLETELY.  As much as I hate
> it when Anthony is right, it is hard to deny it.  I tested further and each
> of these things helped enough that she noticed:  Turning my headset speaker
> down on the inline volume control, turning the headset speaker down at the
> phone, turning my microphone boost down (this headset has 3 settings for
> microphone level), muting at the phone or on the inline headset control.
> All of those things taken collectively say “Listen to Anthony butthead.”**
> **
>
> ** **
>
> So, assuming the cause of the echo is beyond my control (e.g. someone
> else’s phone) are we just screwed or is it just cost prohibitive?  I would
> rather reply that it would cost $5000 to fix it than say “can’t be helped.”
> ****
>
> ** **
>
> Suppose the user detects bad echo.  Is there anything we could do
> (assuming they could notify FS through a programmable key or even web link,
> etc)?  Could we drop the gain to and from the remote end?****
>
> ** **
>
> I promise to let this die now.  Let me here your final thoughts.****
>
> ** **
>
> Thanks again for your time and patience.****
>
> ** **
>
> *From:* freeswitch-users-bounces at lists.freeswitch.org [mailto:
> freeswitch-users-bounces at lists.freeswitch.org] *On Behalf Of *Spencer
> Thomason
> *Sent:* Tuesday, March 19, 2013 11:40 AM
>
> *To:* FreeSWITCH Users Help
> *Subject:* Re: [Freeswitch-users] Removing echo.****
>
> ** **
>
> Hi Sean,****
>
> We were experiencing a similar problem with these units and were able to
> verify that it was in fact the remote end but the threshold of the echo
> canceler seems to be too low by default.  We could hear echo and then
> unplug the handset from the base on the other end, without muting, and the
> echo would stop.  We found that decreasing the gain slightly all but
> eliminated complaints.  This does reduce the level slightly but in our
> traces it was close to on par with an analog handset.  The pertinent
> configuration options are:****
>
> ** **
>
>   <Handset_Input_Gain>-6</Handset_Input_Gain>
>   <Headset_Input_Gain>-6</Headset_Input_Gain>
>   <Speakerphone_Input_Gain>-6</Speakerphone_Input_Gain>
>   <Handset_Additional_Input_Gain>0</Handset_Additional_Input_Gain>
>   <Headset_Additional_Input_Gain>0</Headset_Additional_Input_Gain>
>
> <Speakerphone_Additional_Input_Gain>0</Speakerphone_Additional_Input_Gain>
> ****
>
> ** **
>
> Thanks,****
>
> Spencer****
>
> ** **
>
> ** **
>
> On Mar 19, 2013, at 7:49 AM, Anthony Minessale wrote:****
>
>
>
> ****
>
> Sean,****
>
> ** **
>
> You are welcome to disagree.  Science is driven by people being unwilling
> to accept things as they are.****
>
> I do have some explanations for you if you are interested.****
>
> ** **
>
> Cisco and Linksys ATA both have echo cancelers in them at the point where
> the analog data is converted to digital.  This is the ideal place for it as
> I mentioned earlier.  So they actually are doing something about the
> problem and that is why you do not observe one.  Getting echo while using a
> cell phone is also very common.  The more latency and conversion of the
> audio data you experience, the more likely you can have echo.  (iPhone is
> notorious) The other place where its important to have echo cancellation is
> the point where the digital data in the rtp stream is transferred into the
> TDM gateway interfacing with the PSTN.  This is why most TDM cards like
> Digium and Sangoma have onboard echo canceler chips.  We are not completely
> helpless, we can do some unnatural things like decode the audio signal we
> are passing through and try to run some echo cancellation on it but, in the
> conditions you describe where you hear a perfect replica of what you are
> saying 2-5 seconds later only softer.  That is for sure outside the range
> of any echo canceler.  It cannot reliably tell that this clean signal
> coming many seconds later should be filtered out because its a replica of
> data that has already passed by long before.  Usually in this type of
> issue, you are actually hearing the other side hear what you said.  So you
> say the statement, the latency takes its toll and the echo is coming back
> at you from the far end as they are hearing it.  ****
>
> ** **
>
> I am open to options.  We do have some work on doing some inline audio
> processing underway but we should not rely on them if we can possibly
> control the surroundings better first.  If you are talking to me in the
> same room using a megaphone and I am wearing ear plugs.  Its easier to tell
> you to turn off the megaphone and tell me to remove the ear plugs.****
>
> ** **
>
> ** **
>
> ** **
>
> ** **
>
> On Mon, Mar 18, 2013 at 9:24 PM, Sean Devoy <sdevoy at bizfocused.com> wrote:
> ****
>
> Hey Anthony,****
>
>  ****
>
> Does that mean PBXMate is not worth investigating?****
>
>  ****
>
> I have to disagree here. Placing the blame entirely on the phones at the
> other end doesn’t hold water for me.  I have had echo problems calling from
> my cell phone when leaving a voice mail on FS where there is no phone at
> the other end. So clearly there are situations where it ain’t just the
> phone at the other end.  It also leaves no explanation why Cisco Phones and
> Linksys ATAs don’t have the same problem with Commercial Venders like
> Vonage.  They don’t have anything different at the end of the line for echo
> cancellation then FS does. I have also had users confirm they are still
> getting echo with the microphone MUTED on my end.****
>
>  ****
>
> Again, I love FS and I am not trying to bash anyone or any code.  I am
> just saying there has to be more to this puzzle.  I know what a crappy
> speaker phone’s echo sounds like and I am not at all concerned about that.
> Crappy speaker phones sound like crappy speaker phones no matter what. I
> don’t think that’s what I am trying to track down.  These are business call
> where 90% are using the standard handset on business quality phones.  It
> happens at various levels, but when it is at the bad end of the spectrum
> (e.g. long delay and loud), it does not sound like echo off of walls coming
> back in a microphone.  It is like my input channel has been delayed,
> softened and looped directly back to me crystal clear.  Maybe it is one of
> my VOIP providers’ hardware or software and is load dependent, but the
> problem exists outside of cheap phones. And of course it is only
> reproducible on 3 calls in a hundred at peak usage hours, making it a
> nightmare to track or diagnose.  But those 3 calls are the ones my
> customers want to talk about at billing time.****
>
>  ****
>
> Now, I have just thrown that all out there is hopes that 50 people will
> say “That absolutely never happens to me with FS” so I can look at it a
> different way.****
>
>  ****
>
> Thanks for your thoughts.****
>
> Sean****
>
>  ****
>
> *From:* freeswitch-users-bounces at lists.freeswitch.org [mailto:
> freeswitch-users-bounces at lists.freeswitch.org] *On Behalf Of *Anthony
> Minessale
> *Sent:* Monday, March 18, 2013 7:30 PM****
>
>
> *To:* FreeSWITCH Users Help
> *Subject:* Re: [Freeswitch-users] Removing echo.****
>
> ** **
>
>  ****
>
> The best place for echo cancelation is in the clients as close to the mic
> as possible.****
>
> Someone asked why skype and some apps are better.  It's because they have
> echo cans in the client app.****
>
> Sip soft phones are basically toys unless they have some kind of advanced
> gain and echo controls on your pc because that is where your mic is and
> could have the vol turned up too high etc.****
>
>  ****
>
> From FS perspective in the middle, we can't tell its echo or not because
> we are just passing the data along and we're typically getting it 30-70 ms
> too late.  ****
>
>  ****
>
>  ****
>
> In general, you don't get echo when using real phones because they have
> proper hardware and software to deal with the place where the audio is
> being sampled and rendered.****
>
>  ****
>
>  ****
>
>  ****
>
>  ****
>
>  ****
>
> On Mon, Mar 18, 2013 at 5:15 PM, Christopher Rienzo <cmrienzo at gmail.com>
> wrote:****
>
> Echo cancellation is not easy.  The only open source one I've seen is GPL
> (making it license incompatible with FreeSWITCH) and is not suitable for
> handling echo over IP networks.  Perhaps tricks are being played using VAD
> to only allow only one speaker at a time in the ooVoo conference?****
>
> ** **
>
> On Mon, Mar 18, 2013 at 5:53 PM, Mimiko <vbvbrj at gmail.com> wrote:****
>
> Today we tried ooVoo conference system with theirs client using same
> boxes and microphones - again, no echo. How this can be? Is it only
> commercial products have echo removing function?****
>
>
> --
> Mimiko desu.
>
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> ****
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>  ****
>
> --
> Anthony Minessale II
>
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> ****
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> ** **
>
> --
> Anthony Minessale II
>
> FreeSWITCH http://www.freeswitch.org/
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> Twitter: http://twitter.com/FreeSWITCH_wire
>
> AIM: anthm
> MSN:anthony_minessale at hotmail.com
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>
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>
> _________________________________________________________________________
> Professional FreeSWITCH Consulting Services:
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> http://www.freeswitchsolutions.com
>
> 
> 
>
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