[pulseaudio-discuss] Config option to disable auto microphone boost?

Laszlo KERTESZ laszlo.kertesz at gmail.com
Wed May 11 12:52:09 UTC 2016

Back with more data.
I used this option since then, but it turns out that even if Pulseaudio
doesnt do it,some other apps will still abuse the gain adjustments.

For example i just finished a Google Hangout session (working from my home
desktop) and with "aec_args="analog_gain_control=0\
digital_gain_control=0"" - the mic boost (element "Rear Mic Boost") was
going back to 53 (mid level) causing loud noise when there was silence on
my side (used headphones with microphone).
After i set "volume = zero"
in /usr/share/pulseaudio/alsa-mixer/paths/analog-input-rear-mic.conf,
"[Element Rear Mic Boost]" section and restarted Pulseaudio, AGC
adjustments were still made by Chrome, but only within the "Capture"
control and nobody complained anymore.

So Hangouts does this, and it seems Chrome has AGC built in for "plain"
Webrtc too with no option to disable (i at least couldnt find one). I
tested Jitsi Meet (Webrtc MUC server, locally deployed) and Chrome uses AGC
boost adjustments with the same Pulseaudio setup.

Skype on the other hand always worked just fine with echo-cancel - either
doesn't do AGC on its own or does it better (this point isnt that important
now since it will likely stop working for audio/video in the immediate
future and the browser version will replace it with Webrtc sometimes,
hopefully before it, returning us to the previous point). Thinking about
it, desktop apps in general are echo-cancel-friendly, even the java-powered
Jitsi desktop client.

It seems that in cases like this the "aec_args" are insufficient and some
option should be provided to disable the gain adjustments server-wide since
the editing of the config files are overwritten on Pulseaudio update.

Also note the fact that some sound cards (like most? USB headsets) that
don't have variable mic boost options are immune to this issue. I have one
USB headset wit mic (actually tried multiple models, all with the same
results) at work and they work just fine with echo-cancel regardless of
Pulseaudio's settings.

On Sun, Apr 24, 2016 at 6:29 PM, Tanu Kaskinen <tanuk at iki.fi> wrote:

> On Sat, 2016-04-23 at 17:05 +0300, Laszlo KERTESZ wrote:
> > PS: Is there a documentation somewhere with a list of all aec_args?
> I don't think so. It *should* be documented on
> https://wiki.freedesktop.org/www/Software/PulseAudio/Documentation/User/Modules/
> but isn't. I'll add the documentation at some point (or Arun, would you
> like to do that?)
> --
> Tanu
> _______________________________________________
> pulseaudio-discuss mailing list
> pulseaudio-discuss at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/pulseaudio-discuss
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