title: How do you set the input level (gain) on the built-in input (OSX Core Audio / Audio Unit)?
body: <p>I've got an OSX app that records audio data using an Audio Unit.  The Audio Unit's input can be set to any available source with inputs, including the built-in input.  The problem is, the audio that I get from the built-in input is often clipped, whereas in a program such as Audacity (or even Quicktime) I can turn down the input level and I don't get clipping.</p>
  
  <p>Multiplying the sample frames by a fraction, of course, doesn't work, because I get a lower volume, but the samples themselves are still clipped at time of input.</p>
  
  <p>How do I set the input level or gain for that built-in input to avoid the clipping problem?</p>