Source Code for Module lib.dirty_io

  1   
  2  import re 
  3  import numpy 
  4  from gmisclib import die 
  5  from gmisclib import wavio 
  6  from gmisclib import Numeric_gpk as NG 
  7   
  8 -class BadChannel(ValueError): 
  9 -        def __init__(self, *s): 
 10                  ValueError.__init__(self, *s) 
 11   
 12   
 13  NEARCLIP = 32500 
 14   
 15   
 16           
 17   
 18 -def wav_read(filename, channel=None, info={}): 
 19          """Quick and dirty way to read a single channel of audio from a 
 20          multichannel file.  If the channel is not specified, either as an 
 21          argument or as info['Channel'], then it will pick whatever channel 
 22          has the largest amplitude.   Needless to say, this is not entirely 
 23          reliable unless you know that the other channel is silent. 
 24          @param channel: which channel to use?  It can be a string name, an integer column number 
 25                  or None. 
 26          @param info: a dictionary with miscellaneous metadata.   C{info['Channel']} is inspected. 
 27          @type info: C{dict}. 
 28          @type channel: C{string}, C{int}, or C{None}. 
 29          @return: audio data with header information 
 30                  A gpk_img data structure holding the audio and header information. 
 31                  C{hdr['AudioChannel']}, C{hdr['Trouble']} and C{hdr['WhyAudioChannel']} are set. 
 32          @rtype: gpkimgclass.gpk_img 
 33          @except BadChannel: when you ask for a channel that isn't there. 
 34          @note: Channel numbers start with zero! 
 35          """ 
 36          if channel is None: 
 37                  channel = info.get('Channel', None) 
 38   
 39          x = wavio.read(filename) 
 40          nch0 = x.d.shape[1] 
 41          trouble = [] 
 42          if channel is None and x.d.shape[1] > 1: 
 43                  assert x.d.shape[1] < 1000 
 44                  rms = NG.block_stdev(x.d) 
 45                  channel = numpy.argmax(rms) 
 46                  x.d = x.d.take([channel], axis=1) 
 47                  assert len(x.d.shape) == 2 
 48                  die.info('Taking data from channel %d' % channel) 
 49                  if rms[1-channel] > 0.1*rms[channel]: 
 50                          die.warn('Warning: channel %d is comparable: MAD=%.2g/%.2g' 
 51                                          % (1-channel, rms[1-channel], rms[channel]) 
 52                                          ) 
 53                          x.hdr['WhyAudioChannel'] = 'It was slightly louder' 
 54                          trouble.append('Ambiguous channel') 
 55                  else: 
 56                          x.hdr['WhyAudioChannel'] = 'It was much louder' 
 57          elif channel is None and x.d.shape[1]==1: 
 58                  x.hdr['WhyAudioChannel'] = 'There was only one' 
 59                  channel = 0 
 60          elif channel=='mono': 
 61                  assert x.d.shape[1]==1 
 62                  x.hdr['WhyAudioChannel'] = 'There was only one' 
 63                  channel = 0 
 64          elif 0 <= channel < x.d.shape[1]: 
 65                  x.d = x.d.take([channel], axis=1) 
 66                  x.hdr['WhyAudioChannel'] = 'Specified in g_audioprep.py' 
 67          else: 
 68                  raise BadChannel, "Channel=%s but available channels are %s" % (channel, range(x.d.shape[1])) 
 69   
 70          # x is now reduced to a single channel: 0. 
 71   
 72          if NG.N_maximum(x.column(0)) > NEARCLIP or NG.N_minimum(x.column(0))< -NEARCLIP: 
 73                  da = numpy.absolute(x.column(0)) 
 74                  die.warn("Data is near clipping: maximum abs(value)=%d, %.1f%% near clipping" 
 75                          % (NG.N_maximum(da), numpy.sum(numpy.greater(da, NEARCLIP))/float(da.shape[0]))) 
 76                  trouble.append('Near clipping') 
 77   
 78          x.hdr['Trouble'] = ','.join(trouble) 
 79          assert 0 <= channel < nch0 
 80          x.hdr['AudioChannel'] = channel 
 81          assert x.d.shape[1] == 1 
 82          return x 
 83   
 84   
 85  _nmparse = re.compile(r'(.*)\[([0-9_a-zA-Z]+)\]$') 
 86 -def splitname(filename): 
 87          """Splits filenames in the form pathname[channel] into a pathname 
 88          and a channel. 
 89          """ 
 90          m = _nmparse.match(filename) 
 91          if m: 
 92                  name = m.group(1) 
 93                  try: 
 94                          channel = int(m.group(2)) 
 95                  except ValueError: 
 96                          channel = m.group(2) 
 97          else: 
 98                  name = filename 
 99                  channel = None 
100          return (name, channel) 
101   
102   
103 -def wav_read2(filename): 
104          """Deal with filenames in the form path/name[channel]. 
105          """ 
106          name, channel = splitname(filename) 
107          try: 
108                  rv = wav_read(name, channel=channel, info={}) 
109          except IOError, x: 
110                  raise IOError(*(x.args + ('From dirty_io.wav_read2', 'Filename=%s' % filename))) 
111          return rv 
112