python code read wave file and plot

origin code

1. reference

            import wave
            import pylab as pl
            import numpy as np
   
            f = wave.open(r"c:\\WINDOWS\\Media\\ding.wav", "rb")
   
            # (nchannels, sampwidth, framerate, nframes, comptype, compname)
            params = f.getparams()
            nchannels, sampwidth, framerate, nframes = params[:4]
   
            str_data = f.readframes(nframes)
            f.close()
   
            wave_data = np.fromstring(str_data, dtype=np.short)
            wave_data.shape = -1, 2
            wave_data = wave_data.T
            time = np.arange(0, nframes) * (1.0 / framerate)
   
            pl.subplot(211)
            pl.plot(time, wave_data[0])
            pl.subplot(212)
            pl.plot(time, wave_data[1], c="g")
            pl.xlabel("time (seconds)")
            pl.show()
   

   

modified code

• code

            import wave
            import matplotlib.pyplot as plt
            import numpy as np
  
            f = wave.open("quit.playing.games.wav", "rb")
  
            # (nchannels, sampwidth, framerate, nframes, comptype, compname)
            params = f.getparams()
            nchannels, sampwidth, framerate, nframes = params[:4]
  
            str_data = f.readframes(nframes)
            f.close()
  
            wave_data = np.fromstring(str_data, dtype=np.short)
            wave_data.shape = -1, 2
            wave_data = wave_data.T
            time = np.arange(0, nframes) * (1.0 / framerate)
  
            figure = plt.gcf() # get current figure
            figure.set_size_inches(8*20, 6)
  
            duration = nframes/float(framerate)
            xticks = np.arange(0, duration, 2)
            plt.subplot(211).set_xticks(xticks)
            plt.plot(time, wave_data[0])
            plt.title('quit.playing.games.mp3 channel 1', loc='left')
  
            plt.subplot(212).set_xticks(xticks)
            plt.plot(time, wave_data[1], c="g")
            plt.xlabel("time (seconds)")
            plt.title('quit.playing.games.mp3 channel 2', loc='left')
            plt.savefig('quit.playing.games.png', dpi=100, bbox_inches='tight', pad_inches=0.1)
            #plt.show()
            plt.close(figure)
  

  including images and resources

  

api

1. matplotlib.figure.Figure.set_size_inches(w, h, forword=False)

   • set the figure size in inches (1in == 2.54cm)

   • usage:

           fig.set_size_inches(w, h) # or
           fig.set_size_inches((w, h))
     

   • optional kwarg forword=Ture will cause the canvas size to be automatically updated

2. matplotlib.figure.Figure.savefig(*args, **kwargs)

   • save the current figure

   • call signature

           savefig(fname, dpi=None, facecolor='w', edgecolor='w',
                   orientation='portrait', papertype=None, format=None,
                   transparent=False, bbox_inches=None, pad_inches=0.1, frameon=None)
     

   1. arguments

      1. fname

          a string containing a path to a filename
          if format is None and fname is a string
          the output format is deduced from the extension of the filename
         

   2. keyword arguments

      1. dpi

          [None | scalar > 0]
          the resolution in dots per inche
         

      2. facecolor, edgecolor

          the colors of the figure rectangle
         

      3. orientation [‘landscape’, ‘portrait’]

          not supported on all backends
          current only on postscript output
         

      4. papertype

          one of 'letter', 'legal', 'executive', 'ledger'
          'a0' through 'a10'
          'b0' through 'b10'
          only supported for postscript output
         

      5. format

          one of file extensions supported by the active backend
          most backends support png, pdf, ps, eps and svg
         

      6. transparent

          if True the axes patches will all be transparent
          the figure patch will also be transparent unless facecolor and/or edgecolor are specified via kwargs
         

      7. frameon

          if True the figure patch will be colored
          if False the figure background will be transparent
         

      8. bbox_inches

          Bbox in inches
          only the given portion of the figure is saved
          if 'tight' try to figure out the tight bbox of the figure
         

      9. pad_inches

          amount of padding around the figure when bbox_inches is 'tight'
         

      10. bbox_extra_artists

           a list of extra artists that will be considered when the tight bbox is calculated
          

reference

1. get wav file duration

   • python package songdetails

           In [16]: >>> import songdetails
               ...: >>> song = songdetails.scan("quit.playing.games.mp3")
               ...: >>> song.duration
               ...: >>> print song.duration
               ...:
           0:03:58
     
           In [17]: 3 * 60 + 58
           238
     

   • duration = nframes/float(framerate)

           the duration is equal to the number of frames divided by the framerate (frames per second)
     
           In [18]: duration = nframes/float(framerate)
     
           In [19]: duration
           Out[19]: 238.00163265306122