title: Can you insert an audio unit in a microphone and speaker stream?
body: <p>I am reading about Audio Units on OSX, but it's not totally clear to me what an Audio Unit is.</p>
  <p>I would like to insert custom audio processing in any stream that is being captured from a microphone or played by any application.</p>
  <p>Is it possible to implement the custom audio processing as an Audio Unit which is automatically inserted into any capture or render streams on the machine?</p>
  <p>If so, are there any good examples in the public domain that I can take a look at?</p>
  <p><a href="https://i.stack.imgur.com/9oapK.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/9oapK.png" alt="This is how I imagine it" /></a></p>