title: iOS Audio Toolbox buffer size
body: <p>In an iOS application, the minimum buffer duration of 4 milli seconds is required.
  But the <strong>Audio toolbox</strong> framework provides, 23 milli seconds for 16kHz, mono channel configuration. i.e. it gives <strong>742/744 bytes</strong> at each input callback.</p>
  
  <p>How to make the callback data size as, 128 bytes (4 milli seconds)?</p>
  
  <p>Whether the internal mic (16kHz) or external mic (44.1 kHz) is used, the received callback size is 742/744 bytes (16kHz) only. Not clear about this behavior.</p>
  
  <p>Whereas, in 'AudioUnit' framework, the callback data size gets corrupted, when an extenal mic (44.1 kHz) is connected.</p>