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Re: [Linphone-developers] disable all voice comfort functions

From: Tom Piechotta
Subject: Re: [Linphone-developers] disable all voice comfort functions
Date: Thu, 10 Jan 2019 09:03:18 +0100

Hi Jehan,

Thank you very much for the quick response.

There are two phenomena that seem to be independent:

1) If the same audio signal is transmitted and received at the same time, no sound reaches the remote station. Although the Linphone GUI displays an amplitude at the transmit signal at this moment. If you listen to this tone, the transmit signal is also intact. Even if you change the tone (the different tones have a constant amplitude) no signal will arrive. The only way to fix this is to mute the transmitted signal briefly. The received signal is not affected by this.

2) If the transmission signal already transmits before the call is received, the received signal is mixed proportionally into the transmission signal. This can also be heard by listening to the transmission signal in parallel with headphones. In addition, in this case the transmit signal is also coupled into the receive signal.

The remote station is a mobile radio module that is supplied with an STM microcontroller with audio data. If two of these modules communicate directly with each other via mobile radio, the described phenomena do not occur. Therefore the problem can only be caused by Linphone.

Kind regards

Tom Piechotta

Am Do., 10. Jan. 2019 um 08:41 Uhr schrieb Jehan Monnier <address@hidden>:

Can you elaborate a litle bit more on: «  it seems that the reception and the transmission signal influence each other in some way at the moment. »

Best regards

Le 9 janv. 2019 à 19:13, Tom Piechotta <address@hidden> a écrit :


I am a scientist at the Fraunhofer Heinrich Hertz Institute in Berlin. We use Linphone to control drones via the voice channel of mobile network. This has the advantage that voice data is prioritized in the mobile network and thus a short latency is guaranteed.

To communicate with the drones, we use Linphone on the ground station side. But now we have the problem that not all voice comfort functions can be switched off. We already have some settings in the Linphonerc file:



playback_dev_id=WASAPI: Lautsprecher (VB-Audio Virtual Cable)

capture_dev_id=WASAPI: CABLE-A Output (VB-Audio Cable A)

ringer_dev_id=WASAPI: VoiceMeeter Input (VB-Audio VoiceMeeter VAIO)




remote_ring=C:\Program Files (x86)\Linphone\share/sounds/linphone/ringback.wav




Using only this Codec:







We really only want to send and receive the data 1:1 as we generate it on the PC. However, it seems that the reception and the transmission signal influence each other in some way at the moment.


Can you tell me how to disable the corresponding functions in Linphone?

Kind regards

Tom Piechotta

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