Echo on outgoing calls

[rndthoughts]

Describe the bug When making outgoing calls, the caller can hear themselves speaking a second or so after they have spoken. When calling in from an external device (e.g. mobile phone) this echo does not happen.

To Reproduce Steps to reproduce the behavior:

1. Dial an outgoing number.
2. Callee picks up.
3. Caller can hear their own voice repeated back down the audio output channel.

Expected behavior Caller should not be able to hear themselves played back down the audio channel

Screenshots N/A

Environment (please complete the following information):

• OS: Windows 10
• NAT -> Internet -> NAT
• Latest

App configuration (please complete the following information):

  <sipua srtp="Disabled" secureSignaling="0" logMessages="true" logLevel="5" traceAndDebug="false" autoAnswer="false" autoRecording="false" autoConference="false" maxCalls="5">
    <sipTransport type="udp" Port="5080" />
    <networkSettings natInSDP="true" forceLooseRoute="false">
      <turn enabled="false" server="" type="udp" userName="" password="" realm="" />
      <ice enabled="false" noRTCP="false" />
    </networkSettings>
    <media isVADEnabled="true" />
  </sipua>

Additional context Only happens when the caller is calling out using this library to either an external or internal number.

[siniypin]

Hi, did you play around with Echo Canceller options that are controlled with MediaConfig?

You can set it with values found in pjmedia_echo_flag enum. Give a PJMEDIA_ECHO_SPEEX a try.

More info here: https://www.pjsip.org/docs/latest-1/pjsip/docs/html/structpjsua__media__config.htm#a734653d7e5d075984b9a51f053ded879
and here: https://trac.pjsip.org/repos/wiki/sound-problems

[siniypin]

Also try increasing EcTailLen

[rndthoughts]

When i set either of those two properties (e.g. ecOptions):

<media isVADEnabled="true" ecOptions="1" />

It results in:

[siniypin]

1. It seems unrelated as there is smth running on one of the ports you app is using.
2. I don't think you can set ecOptions with xml config. It simply is not there: https://github.com/siniypin/pjsip4net/blob/master/pjsip4net/Configuration/MediaConfigurationElement.cs#L30

[siniypin]

For some reason I think setting EcTailLen to 500 ms may solve the problem.

[rndthoughts]

Thanks for the pointers - I think the error is misleading me because of the missing automapped properties not existing. When the configuration is loaded and ecOptions is being mapped to a non-existant property it throws:

System.Configuration.ConfigurationErrorsException: 'Unrecognized attribute 'ecOptions'. Note that attribute names are case-sensitive.

This then causes configuration loading to fail hence the PjsipErrorException.

[siniypin]

Yep, you can manipulate config props that aren't available with xml .config during a creation of user agent as in the following example: https://gist.github.com/siniypin/7860386

[rndthoughts]

OK - setting either of those properties doesn't fix the problem. It always affects the outgoing caller. We have managed to run our application a couple of times in between without the echo occurring but after another call it returns.

We are setting the active audio devices using. Is there anything else to be aware of? Could it be something to do with the Windows Wave Mapper?

UserAgent.MediaManager.SetSoundDevices(playbackId, captureId)

[rndthoughts]

Narrowed it down further, it's always the first outgoing call that experiences echo. If that call is hung up then subsequent calls do not experience the problem

[siniypin]

Hmm, that sounds fishy. Can you collect SIP trace as well as library logs? First thing I'd check would be SDP headers to see what are the clients negotiating upon.

[rndthoughts]

Could you point me at some documentation as to how to capture the trace? Do you mean use the logging library in pjsip4net?

[siniypin]

Yes, you need to set the following props in config:

logMessages="true" logLevel="5" traceAndDebug="true"

and route your logs anywhere you like, e.g. to a file with log4net

[rndthoughts]

I've copied the configuration but when running I get -

An error occurred creating the configuration section handler for common/logging: Unable to create type 'Common.Logging.Log4Net.Log4NetLoggerFactoryAdapter, Common.Logging.Log4Net'

[siniypin]

A tiny bit more info here: https://github.com/siniypin/pjsip4net#logging

[siniypin]

Make sure all necessary libraries are there, e.g. log4net.

[rndthoughts]

To get it to run, I had to reference Common.Logging.Log4Net208 to match the log4net version I was running or it couldnt find the adapter. It now runs and should be writing logs to log.txt - presumably in the bin folder, but nothing is output?

[rndthoughts]

Further info - this is only happening when i run the app i've built on two different machines making an internal call. If i mute the sound devices on the callee's app then the caller can still hear their own voice played back to them. So it must be happening on the caller's app.

[rndthoughts]

Found it! I had miscoded what happens when the anwering party picks up and interconnected two slots together twice!

[siniypin]

Hey, glad you've nailed it! Lessons learned? Should pjsip4net raise an exception or at least log a warning when someone tries to interconnect the same port?

[rndthoughts]

I think it's just down to my misunderstanding of how pjsip works in regards to the conference slots. A warning would be good but I never got the logging to work - I just couldnt seem to configure NLog properly and didnt get any text output.

What would be really useful is an example of answering a call in the testing console application as that's what's missing.

I'm aware I've still got an outstanding PR to make on another issue!

[siniypin]

What would be really useful is an example of answering a call in the testing console application as that's what's missing.

That's a good idea, thanks!