title: Open source FSK decoder library?
body: <p>I'm looking for a library or tool to decode FSK in wav files, e.g. caller id.</p>
  
  <p>Currently using the tools bundled with vpb-driver for Voicetronix hardware that is available via debian/ubuntu. But this appears to have an error that I'm trying to debug -- a second tool to validate the audio file would be useful.</p>
  
  <p>I'm <strong>not</strong> looking for any of the myriad tools that read caller id data from a modem or other hardware device -- I need pure software.</p>