Re: Disturbing input gain problem
Re: Disturbing input gain problem
- Subject: Re: Disturbing input gain problem
- From: Brett George <email@hidden>
- Date: Sat, 9 Jul 2011 20:50:27 -0700
You might want to check if the Ambient Noise Reduction is enabled on the internal microphone. Its setting is adjustable in the input pane of the sound preference panel.
Brett.
On Jul 9, 2011, at 8:47 AM, Robert Bielik wrote:
> Hi all,
>
> I use portaudio as middleman for talking to CoreAudio and I've encountered an extremely unpleasant "feature", which I'm pretty 100% sure has nothing
> to do with portaudio itself. Anyway, to make things easy for me, I'm copying the mail I sent to the portaudio list:
>
> -------------------------------
> Hello all,
>
> I'm doing an application which records microphone input, and I've seen a very disturbing "feature": If I set the input gain so that I reach a
> RMS value of about -12 dB in, after a little while the input RMS drops to about -24 dB, and I have not touched anything in the system (!!)
>
> This is _extremely_ disturbing!!
>
> It's just as if an AGC is applied on the input, and this is true for external USB mics aswell as the internal Mac Book microphone. Has anyone
> encountered this ?? I'm using the WaveRT branch, but I've been careful to track trunk changes so that I'm up to date with CoreAudio trunk...
>
> -------------------------------
>
> Has anyone on the CoreAudio list seen anything like this ? And I don't run Skype either which might interfere with the input gain settings...
>
> TIA
> /Rob
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