title: Real-time spectrum analyzer with API
body: <p>I'm looking for a C or C++ API that will give me real-time spectrum analysis of a waveform on Windows.</p>
  
  <p>I'm not <strong>entirely</strong> sure how large a sample window it should need to determine frequency content, but the smaller the better.  For example, if it can work with a 0.5 second long sample and determine frequency content to the Hz, that would be wicked-awesome.</p>