[pulseaudio-discuss] module-echo-cancel microphone gain auto-adjust

Arun Raghavan arun at arunraghavan.net
Tue Mar 7 06:08:25 UTC 2017


On Sun, 5 Mar 2017, at 12:11 AM, Vasco Almeida wrote:
> A terça-feira, 21 de fevereiro de 2017 08:51:14 AZOT Vasco Almeida
> escreveu:
> > Hello.
> > I know that module-echo-cancel used to auto-adjust the gain of
> > microphone while one speaks. I used to see in pavucontrol the slider
> > move change the microphone gain. Now I don't see that happen anymore.
> > Was this feature removed or disabled?
> > I see this new behavior in Fedora 25 and OpenSUSE Tumbleweed.
> > How can I have microphone gain auto-adjust again?
> > 
> > I have searched a little to see what I could find about the issue but I
> > found nothing. This may be something new.
> > Please reply to me because I am not subscribed to the list.
> > Thank you.
> pulseaudio 10.0
> pactl load-module module-echo-cancel aec_method=webrtc
> pactl load-module module-echo-cancel aec_method=webrtc 
> aec_args=agc_start_volume=200
> or without aec_method or other arguments.
> So far I could see the microphone slider move left only when the gain is
> 100% 
> and I yell. When I set the gain to low the slider does not move at all to
> pick 
> my voice.
> On fedora 24 automatic gain control for microphone with
> module-echo-cancel 
> works fine. On fedora 24 at the time of writing there is 
> pulseaudio-8.0-6.fc24.
> From PulseAudio 9.0 release notes [1]
> > It's now possible to configure the initial volume when using AGC (automatic
> > gain control). To do that, pass "agc_start_volume=VOL" in aec_args when
> > loading module-echo-cancel (replace VOL with a number between 0 and 255).
> > Note that too low initial volume may prevent the AGC algorithm from ever
> > raising the volume high enough (there seems to be some regression in the
> > WebRTC code in this regard).
> Would the above change affect the automatic gain control that it does not
> work 
> for me anymore?

The update to webrtc-audio-processing did make the AGC less quick to
react to input energy level changes. We might need to update the code
based on upstream again to see if things have gotten better.

By default, is the level of your mic (without module-echo-cancel)
sufficiently high? I would not expect this to be a problem if it is.


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