[pulseaudio-discuss] Macbook Pro specific problem

Nick Thompson rextanka at comcast.net
Tue Sep 2 09:46:57 PDT 2008

The speaker is disabled on that side when the mic is active in Mac OS  
X.  This is true of all MacBook Pro versions Apple has shipped.  The  
switching happens in the driver for the codec in onboard audio.

You really have two options.

First is you could modify the alsa driver for the ALC885 (if if it's  
an earlier model the Sigmatel 9220) to mute the channel the speaker is  
on when the Mic is active.

Second option is two write a PulseAudio module that intercepts source- 
output creation and when active mixes the sink-input for the speakers  
to mono and output silence on the left channel and the mixed signal on  
the right.  This is going to be the path of least resistance, since if  
you are not a driver guy, then the driver may be more pain than you  

Either is going to require you write some code though.  However the  
module part is not too difficult once you get your head around the  
APIs - the example modules have a few clues on how to do this too.

-- Nick

On Aug 30, 2008, at 6:08 AM, Alexey Kuznetsov wrote:

> I have macbook pro notebook. I wana ask you about specificity  
> hardware problem related to this notebook model. In macbook pro  
> microphone placed in same position with left speaker. As the result  
> when i try to record sound i got sound echo and can hear my voice.  
> Another problem happens when i spok with my skype friends. If my  
> firend say sonting they got self voice echo imidiatly back.
> The question is : now i can create trigger when record device  
> (microphone) is enabled in pulseaudio and some programm ready to  
> record sounds my trigger turn left speaker output to 0% volume and  
> put all sounds to right speaker?

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