Lib/sndhdr.py

   1 # This module contains several routines that help recognizing sound
   2 # files.
   3 #
   4 # Function whathdr() recognizes various types of sound file headers.
   5 # It understands almost all headers that SOX can decode.
   6 #
   7 # The return tuple contains the following items, in this order:
   8 # - file type (as SOX understands it)
   9 # - sampling rate (0 if unknown or hard to decode)
  10 # - number of channels (0 if unknown or hard to decode)
  11 # - number of frames in the file (-1 if unknown or hard to decode)
  12 # - number of bits/sample, or 'U' for U-LAW, or 'A' for A-LAW
  13 #
  14 # If the file doesn't have a recognizable type, it returns None.
  15 # If the file can't be opened, IOError is raised.
  16 #
  17 # To compute the total time, divide the number of frames by the
  18 # sampling rate (a frame contains a sample for each channel).
  19 #
  20 # Function whatraw() calls the "whatsound" program and interprets its
  21 # output.  You'll have to guess the sampling rate by listening though!
  22 #
  23 # Function what() calls whathdr() and if it doesn't recognize the file
  24 # then calls whatraw().
  25 #
  26 # Finally, the function test() is a simple main program that calls
  27 # what() for all files mentioned on the argument list.  For directory
  28 # arguments it calls what() for all files in that directory.  Default
  29 # argument is "." (testing all files in the current directory).  The
  30 # option -r tells it to recurse down directories found inside
  31 # explicitly given directories.
  32 #
  33 # The file structure is top-down except that the test program and its
  34 # subroutine come last.
  35
  36
  37 #------------------------------------------------------#
  38 # Guess the type of any sound file, raw or with header #
  39 #------------------------------------------------------#
  40
  41 def what(filename):
  42         res = whathdr(filename)
  43         if not res:
  44                 res = whatraw(filename)
  45         return res
  46
  47
  48 #-----------------------------#
  49 # Guess the type of raw sound #
  50 #-----------------------------#
  51
  52 def whatraw(filename):
  53         # Assume it's always 1 channel, byte-sized samples
  54         # Don't assume anything about the rate
  55         import os
  56         from stat import ST_SIZE
  57         # XXX "whatsound" should be part of the distribution somehow...
  58         cmd = 'whatsound ' + filename + ' 2>/dev/null'
  59         cmd = 'PATH=$PATH:/ufs/guido/bin/sgi\n' + cmd
  60         pipe = os.popen(cmd, 'r')
  61         data = pipe.read()
  62         sts = pipe.close()
  63         if sts:
  64                 return None
  65         if data[:13] == '-t raw -b -s ':
  66                 type = 'sb'
  67                 sample_size = 8
  68         elif data[:13] == '-t raw -b -u ':
  69                 type = 'ub'
  70                 sample_size = 8
  71         elif data[:13] == '-t raw -b -U ':
  72                 type = 'ul'
  73                 sample_size = 'U'
  74         else:
  75                 return None
  76         try:
  77                 frame_count = os.stat(filename)[ST_SIZE]
  78         except IOError:
  79                 frame_count = -1
  80         return type, 0, 1, frame_count, sample_size
  81
  82
  83 #-------------------------#
  84 # Recognize sound headers #
  85 #-------------------------#
  86
  87 def whathdr(filename):
  88         f = open(filename, 'r')
  89         h = f.read(512)
  90         for tf in tests:
  91                 res = tf(h, f)
  92                 if res:
  93                         return res
  94         return None
  95
  96
  97 #-----------------------------------#
  98 # Subroutines per sound header type #
  99 #-----------------------------------#
 100
 101 tests = []
 102
 103 def test_aifc(h, f):
 104         import aifc
 105         if h[:4] <> 'FORM':
 106                 return None
 107         if h[8:12] == 'AIFC':
 108                 fmt = 'aifc'
 109         elif h[8:12] == 'AIFF':
 110                 fmt = 'aiff'
 111         else:
 112                 return None
 113         f.seek(0)
 114         try:
 115                 a = aifc.openfp(f, 'r')
 116         except (EOFError, aifc.Error):
 117                 return None
 118         return (fmt, a.getframerate(), a.getnchannels(), \
 119                 a.getnframes(), 8*a.getsampwidth())
 120
 121 tests.append(test_aifc)
 122
 123
 124 def test_au(h, f):
 125         if h[:4] == '.snd':
 126                 f = get_long_be
 127         elif h[:4] in ('\0ds.', 'dns.'):
 128                 f = get_long_le
 129         else:
 130                 return None
 131         type = 'au'
 132         hdr_size = f(h[4:8])
 133         data_size = f(h[8:12])
 134         encoding = f(h[12:16])
 135         rate = f(h[16:20])
 136         nchannels = f(h[20:24])
 137         sample_size = 1 # default
 138         if encoding == 1:
 139                 sample_bits = 'U'
 140         elif encoding == 2:
 141                 sample_bits = 8
 142         elif encoding == 3:
 143                 sample_bits = 16
 144                 sample_size = 2
 145         else:
 146                 sample_bits = '?'
 147         frame_size = sample_size * nchannels
 148         return type, rate, nchannels, data_size/frame_size, sample_bits
 149
 150 tests.append(test_au)
 151
 152
 153 def test_hcom(h, f):
 154         if h[65:69] <> 'FSSD' or h[128:132] <> 'HCOM':
 155                 return None
 156         divisor = get_long_be(h[128+16:128+20])
 157         return 'hcom', 22050/divisor, 1, -1, 8
 158
 159 tests.append(test_hcom)
 160
 161
 162 def test_voc(h, f):
 163         if h[:20] <> 'Creative Voice File\032':
 164                 return None
 165         sbseek = get_short_le(h[20:22])
 166         rate = 0
 167         if 0 <= sbseek < 500 and h[sbseek] == '\1':
 168                 ratecode = ord(h[sbseek+4])
 169                 rate = int(1000000.0 / (256 - ratecode))
 170         return 'voc', rate, 1, -1, 8
 171
 172 tests.append(test_voc)
 173
 174
 175 def test_wav(h, f):
 176         # 'RIFF' <len> 'WAVE' 'fmt ' <len>
 177         if h[:4] <> 'RIFF' or h[8:12] <> 'WAVE' or h[12:16] <> 'fmt ':
 178                 return None
 179         style = get_short_le(h[20:22])
 180         nchannels = get_short_le(h[22:24])
 181         rate = get_long_le(h[24:28])
 182         sample_bits = get_short_le(h[34:36])
 183         return 'wav', rate, nchannels, -1, sample_bits
 184
 185 tests.append(test_wav)
 186
 187
 188 def test_8svx(h, f):
 189         if h[:4] <> 'FORM' or h[8:12] <> '8SVX':
 190                 return None
 191         # Should decode it to get #channels -- assume always 1
 192         return '8svx', 0, 1, 0, 8
 193
 194 tests.append(test_8svx)
 195
 196
 197 def test_sndt(h, f):
 198         if h[:5] == 'SOUND':
 199                 nsamples = get_long_le(h[8:12])
 200                 rate = get_short_le(h[20:22])
 201                 return 'sndt', rate, 1, nsamples, 8
 202
 203 tests.append(test_sndt)
 204
 205
 206 def test_sndr(h, f):
 207         if h[:2] == '\0\0':
 208                 rate = get_short_le(h[2:4])
 209                 if 4000 <= rate <= 25000:
 210                         return 'sndr', rate, 1, -1, 8
 211
 212 tests.append(test_sndr)
 213
 214
 215 #---------------------------------------------#
 216 # Subroutines to extract numbers from strings #
 217 #---------------------------------------------#
 218
 219 def get_long_be(s):
 220         return (ord(s[0])<<24) | (ord(s[1])<<16) | (ord(s[2])<<8) | ord(s[3])
 221
 222 def get_long_le(s):
 223         return (ord(s[3])<<24) | (ord(s[2])<<16) | (ord(s[1])<<8) | ord(s[0])
 224
 225 def get_short_be(s):
 226         return (ord(s[0])<<8) | ord(s[1])
 227
 228 def get_short_le(s):
 229         return (ord(s[1])<<8) | ord(s[0])
 230
 231
 232 #--------------------#
 233 # Small test program #
 234 #--------------------#
 235
 236 def test():
 237         import sys
 238         recursive = 0
 239         if sys.argv[1:] and sys.argv[1] == '-r':
 240                 del sys.argv[1:2]
 241                 recursive = 1
 242         try:
 243                 if sys.argv[1:]:
 244                         testall(sys.argv[1:], recursive, 1)
 245                 else:
 246                         testall(['.'], recursive, 1)
 247         except KeyboardInterrupt:
 248                 sys.stderr.write('\n[Interrupted]\n')
 249                 sys.exit(1)
 250
 251 def testall(list, recursive, toplevel):
 252         import sys
 253         import os
 254         for filename in list:
 255                 if os.path.isdir(filename):
 256                         print filename + '/:',
 257                         if recursive or toplevel:
 258                                 print 'recursing down:'
 259                                 import glob
 260                                 names = glob.glob(os.path.join(filename, '*'))
 261                                 testall(names, recursive, 0)
 262                         else:
 263                                 print '*** directory (use -r) ***'
 264                 else:
 265                         print filename + ':',
 266                         sys.stdout.flush()
 267                         try:
 268                                 print what(filename)
 269                         except IOError:
 270                                 print '*** not found ***'