Taming Yosemite mic volume & AGC from Livecode

[Keith Clarke]

Hi Folks,
A question for any Mac audio experts in the virtual room.

The Problem
Some colleagues are having problems with multiple apps fighting over OSX (Yosemite) microphone levels - and auto-adjusting the Automatic Gain Control (AGC) in real-time. Apps include Skype, GotoMeeting, Webex, Google hangouts, various soft-phones… 

The biggest issue is apps ramping-up input volume/AGC to the max in the background, creating noise, feedback & distortion for the other parties involved - all without the (non-technical, BYOD) user being aware unless they monitor system preferences all the while and ‘ride the faders’.

There are various threads around on settings for specific apps but I’ve not found a definitive answer for overriding a bunch of disparate apps that don’t play nice - on other folks’ machines. Furthermore, Yosemite’s System preferences for Sound doesn’t seem to provide a true, ‘absolute' Master Volume control - nor does it provide a master AGC On/Off. 

Potential Solution?
So, I wonder if the way OSX audio settings work might allow a way to create a simple 'one knob + one button' Livecode utility that they can have on screen that drives Applescripts to get/set input volume and provide a global AGC on/off switch?

So far we’ve tried this rather 'blunt instrument' volume reset via Terminal to address some of the symptoms…

osascript -e repeat -e "set volume input volume 15” -e 'delay 1’ -e 'end repeat’

… but it would be nice to refine the behaviour, add AGC control to prevent unwanted adjustments and wrap it for use in a user-friendly Livecode stack.  

Any ideas gratefully received. :-)
Best,
Keith..