content: #! /usr/bin/env python
  
  import sys
  from aubio import pvoc, source
  from numpy import zeros, hstack
  
  def get_waveform_plot(filename, samplerate = 0, block_size = 4096, ax = None, downsample = 2**4):
      import matplotlib.pyplot as plt
      if not ax:
          fig = plt.figure()
          ax = fig.add_subplot(111)
      hop_s = block_size
  
      allsamples_max = zeros(0,)
      downsample = downsample  # to plot n samples / hop_s
  
      a = source(filename, samplerate, hop_s)            # source file
      if samplerate == 0: samplerate = a.samplerate
  
      total_frames = 0
      while True:
          samples, read = a()
          # keep some data to plot it later
          new_maxes = (abs(samples.reshape(hop_s/downsample, downsample))).max(axis=0)
          allsamples_max = hstack([allsamples_max, new_maxes])
          total_frames += read
          if read < hop_s: break
      allsamples_max = (allsamples_max > 0) * allsamples_max
      allsamples_max_times = [ ( float (t) / downsample ) * hop_s for t in range(len(allsamples_max)) ]
  
      ax.plot(allsamples_max_times,  allsamples_max, '-b')
      ax.plot(allsamples_max_times, -allsamples_max, '-b')
      ax.axis(xmin = allsamples_max_times[0], xmax = allsamples_max_times[-1])
  
      set_xlabels_sample2time(ax, allsamples_max_times[-1], samplerate)
      return ax
  
  def set_xlabels_sample2time(ax, latest_sample, samplerate):
      ax.axis(xmin = 0, xmax = latest_sample)
      if latest_sample / float(samplerate) > 60:
          ax.set_xlabel('time (mm:ss)')
          ax.set_xticklabels([ "%02d:%02d" % (t/float(samplerate)/60, (t/float(samplerate))%60) for t in ax.get_xticks()[:-1]], rotation = 50)
      else:
          ax.set_xlabel('time (ss.mm)')
          ax.set_xticklabels([ "%02d.%02d" % (t/float(samplerate), 100*((t/float(samplerate))%1) ) for t in ax.get_xticks()[:-1]], rotation = 50)
  
  
  if __name__ == '__main__':
      import matplotlib.pyplot as plt
      if len(sys.argv) < 2:
          print "Usage: %s <filename>" % sys.argv[0]
      else:
          for soundfile in sys.argv[1:]:
              get_waveform_plot(soundfile)
              # display graph
              plt.show()
  