blob: b993b400c2ca5d6e0221d754b1d2d3c110458672 [file] [log] [blame]
Guido van Rossume7b146f2000-02-04 15:28:42 +00001"""Stuff to parse WAVE files.
2
3Usage.
4
5Reading WAVE files:
6 f = wave.open(file, 'r')
7where file is either the name of a file or an open file pointer.
8The open file pointer must have methods read(), seek(), and close().
9When the setpos() and rewind() methods are not used, the seek()
10method is not necessary.
11
12This returns an instance of a class with the following public methods:
13 getnchannels() -- returns number of audio channels (1 for
14 mono, 2 for stereo)
15 getsampwidth() -- returns sample width in bytes
16 getframerate() -- returns sampling frequency
17 getnframes() -- returns number of audio frames
18 getcomptype() -- returns compression type ('NONE' for linear samples)
19 getcompname() -- returns human-readable version of
20 compression type ('not compressed' linear samples)
21 getparams() -- returns a tuple consisting of all of the
22 above in the above order
23 getmarkers() -- returns None (for compatibility with the
24 aifc module)
25 getmark(id) -- raises an error since the mark does not
26 exist (for compatibility with the aifc module)
27 readframes(n) -- returns at most n frames of audio
28 rewind() -- rewind to the beginning of the audio stream
29 setpos(pos) -- seek to the specified position
30 tell() -- return the current position
31 close() -- close the instance (make it unusable)
32The position returned by tell() and the position given to setpos()
Thomas Wouters7e474022000-07-16 12:04:32 +000033are compatible and have nothing to do with the actual position in the
Guido van Rossume7b146f2000-02-04 15:28:42 +000034file.
35The close() method is called automatically when the class instance
36is destroyed.
37
38Writing WAVE files:
39 f = wave.open(file, 'w')
40where file is either the name of a file or an open file pointer.
41The open file pointer must have methods write(), tell(), seek(), and
42close().
43
44This returns an instance of a class with the following public methods:
45 setnchannels(n) -- set the number of channels
46 setsampwidth(n) -- set the sample width
47 setframerate(n) -- set the frame rate
48 setnframes(n) -- set the number of frames
49 setcomptype(type, name)
50 -- set the compression type and the
51 human-readable compression type
52 setparams(tuple)
53 -- set all parameters at once
54 tell() -- return current position in output file
55 writeframesraw(data)
56 -- write audio frames without pathing up the
57 file header
58 writeframes(data)
59 -- write audio frames and patch up the file header
60 close() -- patch up the file header and close the
61 output file
62You should set the parameters before the first writeframesraw or
63writeframes. The total number of frames does not need to be set,
64but when it is set to the correct value, the header does not have to
65be patched up.
66It is best to first set all parameters, perhaps possibly the
67compression type, and then write audio frames using writeframesraw.
68When all frames have been written, either call writeframes('') or
69close() to patch up the sizes in the header.
70The close() method is called automatically when the class instance
71is destroyed.
72"""
Guido van Rossum3ed23cc1994-02-15 15:57:15 +000073
74import __builtin__
75
Skip Montanaro40fc1602001-03-01 04:27:19 +000076__all__ = ["open", "openfp", "Error"]
77
Fred Drake9b8d8012000-08-17 04:45:13 +000078class Error(Exception):
79 pass
Guido van Rossum3ed23cc1994-02-15 15:57:15 +000080
81WAVE_FORMAT_PCM = 0x0001
82
83_array_fmts = None, 'b', 'h', None, 'l'
84
Guido van Rossumebb9c921999-02-05 22:28:17 +000085# Determine endian-ness
86import struct
87if struct.pack("h", 1) == "\000\001":
Guido van Rossume7b146f2000-02-04 15:28:42 +000088 big_endian = 1
Guido van Rossumebb9c921999-02-05 22:28:17 +000089else:
Guido van Rossume7b146f2000-02-04 15:28:42 +000090 big_endian = 0
Guido van Rossumebb9c921999-02-05 22:28:17 +000091
Guido van Rossum3601e881999-08-26 15:50:43 +000092from chunk import Chunk
Guido van Rossum3ed23cc1994-02-15 15:57:15 +000093
94class Wave_read:
Guido van Rossume7b146f2000-02-04 15:28:42 +000095 """Variables used in this class:
Guido van Rossum3ed23cc1994-02-15 15:57:15 +000096
Guido van Rossume7b146f2000-02-04 15:28:42 +000097 These variables are available to the user though appropriate
98 methods of this class:
99 _file -- the open file with methods read(), close(), and seek()
100 set through the __init__() method
101 _nchannels -- the number of audio channels
102 available through the getnchannels() method
103 _nframes -- the number of audio frames
104 available through the getnframes() method
105 _sampwidth -- the number of bytes per audio sample
106 available through the getsampwidth() method
107 _framerate -- the sampling frequency
108 available through the getframerate() method
109 _comptype -- the AIFF-C compression type ('NONE' if AIFF)
110 available through the getcomptype() method
111 _compname -- the human-readable AIFF-C compression type
112 available through the getcomptype() method
113 _soundpos -- the position in the audio stream
114 available through the tell() method, set through the
115 setpos() method
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000116
Guido van Rossume7b146f2000-02-04 15:28:42 +0000117 These variables are used internally only:
118 _fmt_chunk_read -- 1 iff the FMT chunk has been read
119 _data_seek_needed -- 1 iff positioned correctly in audio
120 file for readframes()
121 _data_chunk -- instantiation of a chunk class for the DATA chunk
122 _framesize -- size of one frame in the file
123 """
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000124
Guido van Rossume7b146f2000-02-04 15:28:42 +0000125 def initfp(self, file):
126 self._convert = None
127 self._soundpos = 0
128 self._file = Chunk(file, bigendian = 0)
129 if self._file.getname() != 'RIFF':
130 raise Error, 'file does not start with RIFF id'
131 if self._file.read(4) != 'WAVE':
132 raise Error, 'not a WAVE file'
133 self._fmt_chunk_read = 0
134 self._data_chunk = None
135 while 1:
136 self._data_seek_needed = 1
137 try:
138 chunk = Chunk(self._file, bigendian = 0)
139 except EOFError:
140 break
141 chunkname = chunk.getname()
142 if chunkname == 'fmt ':
143 self._read_fmt_chunk(chunk)
144 self._fmt_chunk_read = 1
145 elif chunkname == 'data':
146 if not self._fmt_chunk_read:
147 raise Error, 'data chunk before fmt chunk'
148 self._data_chunk = chunk
Guido van Rossum54e54c62001-09-04 19:14:14 +0000149 self._nframes = chunk.chunksize // self._framesize
Guido van Rossume7b146f2000-02-04 15:28:42 +0000150 self._data_seek_needed = 0
151 break
152 chunk.skip()
153 if not self._fmt_chunk_read or not self._data_chunk:
154 raise Error, 'fmt chunk and/or data chunk missing'
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000155
Guido van Rossume7b146f2000-02-04 15:28:42 +0000156 def __init__(self, f):
Tim Peterscfc41782000-10-09 23:43:55 +0000157 self._i_opened_the_file = None
Neal Norwitz0e67fd42004-08-01 22:48:06 +0000158 if isinstance(f, basestring):
Guido van Rossume7b146f2000-02-04 15:28:42 +0000159 f = __builtin__.open(f, 'rb')
Tim Peterscfc41782000-10-09 23:43:55 +0000160 self._i_opened_the_file = f
Guido van Rossume7b146f2000-02-04 15:28:42 +0000161 # else, assume it is an open file object already
Georg Brandlab1f4672007-03-15 07:41:30 +0000162 try:
163 self.initfp(f)
164 except:
165 if self._i_opened_the_file:
166 f.close()
167 raise
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000168
Tim Peterscfc41782000-10-09 23:43:55 +0000169 def __del__(self):
170 self.close()
Guido van Rossume7b146f2000-02-04 15:28:42 +0000171 #
172 # User visible methods.
173 #
174 def getfp(self):
175 return self._file
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000176
Guido van Rossume7b146f2000-02-04 15:28:42 +0000177 def rewind(self):
178 self._data_seek_needed = 1
179 self._soundpos = 0
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000180
Guido van Rossume7b146f2000-02-04 15:28:42 +0000181 def close(self):
Tim Peterscfc41782000-10-09 23:43:55 +0000182 if self._i_opened_the_file:
183 self._i_opened_the_file.close()
184 self._i_opened_the_file = None
Guido van Rossume7b146f2000-02-04 15:28:42 +0000185 self._file = None
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000186
Guido van Rossume7b146f2000-02-04 15:28:42 +0000187 def tell(self):
188 return self._soundpos
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000189
Guido van Rossume7b146f2000-02-04 15:28:42 +0000190 def getnchannels(self):
191 return self._nchannels
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000192
Guido van Rossume7b146f2000-02-04 15:28:42 +0000193 def getnframes(self):
194 return self._nframes
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000195
Guido van Rossume7b146f2000-02-04 15:28:42 +0000196 def getsampwidth(self):
197 return self._sampwidth
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000198
Guido van Rossume7b146f2000-02-04 15:28:42 +0000199 def getframerate(self):
200 return self._framerate
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000201
Guido van Rossume7b146f2000-02-04 15:28:42 +0000202 def getcomptype(self):
203 return self._comptype
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000204
Guido van Rossume7b146f2000-02-04 15:28:42 +0000205 def getcompname(self):
206 return self._compname
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000207
Guido van Rossume7b146f2000-02-04 15:28:42 +0000208 def getparams(self):
209 return self.getnchannels(), self.getsampwidth(), \
210 self.getframerate(), self.getnframes(), \
211 self.getcomptype(), self.getcompname()
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000212
Guido van Rossume7b146f2000-02-04 15:28:42 +0000213 def getmarkers(self):
214 return None
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000215
Guido van Rossume7b146f2000-02-04 15:28:42 +0000216 def getmark(self, id):
217 raise Error, 'no marks'
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000218
Guido van Rossume7b146f2000-02-04 15:28:42 +0000219 def setpos(self, pos):
220 if pos < 0 or pos > self._nframes:
221 raise Error, 'position not in range'
222 self._soundpos = pos
223 self._data_seek_needed = 1
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000224
Guido van Rossume7b146f2000-02-04 15:28:42 +0000225 def readframes(self, nframes):
226 if self._data_seek_needed:
227 self._data_chunk.seek(0, 0)
228 pos = self._soundpos * self._framesize
229 if pos:
230 self._data_chunk.seek(pos, 0)
231 self._data_seek_needed = 0
232 if nframes == 0:
233 return ''
234 if self._sampwidth > 1 and big_endian:
235 # unfortunately the fromfile() method does not take
236 # something that only looks like a file object, so
237 # we have to reach into the innards of the chunk object
238 import array
239 chunk = self._data_chunk
240 data = array.array(_array_fmts[self._sampwidth])
241 nitems = nframes * self._nchannels
242 if nitems * self._sampwidth > chunk.chunksize - chunk.size_read:
243 nitems = (chunk.chunksize - chunk.size_read) / self._sampwidth
244 data.fromfile(chunk.file.file, nitems)
245 # "tell" data chunk how much was read
246 chunk.size_read = chunk.size_read + nitems * self._sampwidth
247 # do the same for the outermost chunk
248 chunk = chunk.file
249 chunk.size_read = chunk.size_read + nitems * self._sampwidth
250 data.byteswap()
251 data = data.tostring()
252 else:
253 data = self._data_chunk.read(nframes * self._framesize)
254 if self._convert and data:
255 data = self._convert(data)
Guido van Rossum54e54c62001-09-04 19:14:14 +0000256 self._soundpos = self._soundpos + len(data) // (self._nchannels * self._sampwidth)
Guido van Rossume7b146f2000-02-04 15:28:42 +0000257 return data
258
259 #
260 # Internal methods.
261 #
262
263 def _read_fmt_chunk(self, chunk):
264 wFormatTag, self._nchannels, self._framerate, dwAvgBytesPerSec, wBlockAlign = struct.unpack('<hhllh', chunk.read(14))
265 if wFormatTag == WAVE_FORMAT_PCM:
266 sampwidth = struct.unpack('<h', chunk.read(2))[0]
Guido van Rossum54e54c62001-09-04 19:14:14 +0000267 self._sampwidth = (sampwidth + 7) // 8
Guido van Rossume7b146f2000-02-04 15:28:42 +0000268 else:
Walter Dörwald70a6b492004-02-12 17:35:32 +0000269 raise Error, 'unknown format: %r' % (wFormatTag,)
Guido van Rossume7b146f2000-02-04 15:28:42 +0000270 self._framesize = self._nchannels * self._sampwidth
271 self._comptype = 'NONE'
272 self._compname = 'not compressed'
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000273
274class Wave_write:
Guido van Rossume7b146f2000-02-04 15:28:42 +0000275 """Variables used in this class:
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000276
Guido van Rossume7b146f2000-02-04 15:28:42 +0000277 These variables are user settable through appropriate methods
278 of this class:
279 _file -- the open file with methods write(), close(), tell(), seek()
280 set through the __init__() method
281 _comptype -- the AIFF-C compression type ('NONE' in AIFF)
282 set through the setcomptype() or setparams() method
283 _compname -- the human-readable AIFF-C compression type
284 set through the setcomptype() or setparams() method
285 _nchannels -- the number of audio channels
286 set through the setnchannels() or setparams() method
287 _sampwidth -- the number of bytes per audio sample
288 set through the setsampwidth() or setparams() method
289 _framerate -- the sampling frequency
290 set through the setframerate() or setparams() method
291 _nframes -- the number of audio frames written to the header
292 set through the setnframes() or setparams() method
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000293
Guido van Rossume7b146f2000-02-04 15:28:42 +0000294 These variables are used internally only:
295 _datalength -- the size of the audio samples written to the header
296 _nframeswritten -- the number of frames actually written
297 _datawritten -- the size of the audio samples actually written
298 """
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000299
Guido van Rossume7b146f2000-02-04 15:28:42 +0000300 def __init__(self, f):
Tim Peterscfc41782000-10-09 23:43:55 +0000301 self._i_opened_the_file = None
Neal Norwitz0e67fd42004-08-01 22:48:06 +0000302 if isinstance(f, basestring):
Guido van Rossume7b146f2000-02-04 15:28:42 +0000303 f = __builtin__.open(f, 'wb')
Tim Peterscfc41782000-10-09 23:43:55 +0000304 self._i_opened_the_file = f
Georg Brandlab1f4672007-03-15 07:41:30 +0000305 try:
306 self.initfp(f)
307 except:
308 if self._i_opened_the_file:
309 f.close()
310 raise
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000311
Guido van Rossume7b146f2000-02-04 15:28:42 +0000312 def initfp(self, file):
313 self._file = file
314 self._convert = None
315 self._nchannels = 0
316 self._sampwidth = 0
317 self._framerate = 0
318 self._nframes = 0
319 self._nframeswritten = 0
320 self._datawritten = 0
321 self._datalength = 0
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000322
Guido van Rossume7b146f2000-02-04 15:28:42 +0000323 def __del__(self):
Tim Peterscfc41782000-10-09 23:43:55 +0000324 self.close()
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000325
Guido van Rossume7b146f2000-02-04 15:28:42 +0000326 #
327 # User visible methods.
328 #
329 def setnchannels(self, nchannels):
330 if self._datawritten:
331 raise Error, 'cannot change parameters after starting to write'
332 if nchannels < 1:
333 raise Error, 'bad # of channels'
334 self._nchannels = nchannels
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000335
Guido van Rossume7b146f2000-02-04 15:28:42 +0000336 def getnchannels(self):
337 if not self._nchannels:
338 raise Error, 'number of channels not set'
339 return self._nchannels
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000340
Guido van Rossume7b146f2000-02-04 15:28:42 +0000341 def setsampwidth(self, sampwidth):
342 if self._datawritten:
343 raise Error, 'cannot change parameters after starting to write'
344 if sampwidth < 1 or sampwidth > 4:
345 raise Error, 'bad sample width'
346 self._sampwidth = sampwidth
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000347
Guido van Rossume7b146f2000-02-04 15:28:42 +0000348 def getsampwidth(self):
349 if not self._sampwidth:
350 raise Error, 'sample width not set'
351 return self._sampwidth
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000352
Guido van Rossume7b146f2000-02-04 15:28:42 +0000353 def setframerate(self, framerate):
354 if self._datawritten:
355 raise Error, 'cannot change parameters after starting to write'
356 if framerate <= 0:
357 raise Error, 'bad frame rate'
358 self._framerate = framerate
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000359
Guido van Rossume7b146f2000-02-04 15:28:42 +0000360 def getframerate(self):
361 if not self._framerate:
362 raise Error, 'frame rate not set'
363 return self._framerate
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000364
Guido van Rossume7b146f2000-02-04 15:28:42 +0000365 def setnframes(self, nframes):
366 if self._datawritten:
367 raise Error, 'cannot change parameters after starting to write'
368 self._nframes = nframes
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000369
Guido van Rossume7b146f2000-02-04 15:28:42 +0000370 def getnframes(self):
371 return self._nframeswritten
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000372
Guido van Rossume7b146f2000-02-04 15:28:42 +0000373 def setcomptype(self, comptype, compname):
374 if self._datawritten:
375 raise Error, 'cannot change parameters after starting to write'
376 if comptype not in ('NONE',):
377 raise Error, 'unsupported compression type'
378 self._comptype = comptype
379 self._compname = compname
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000380
Guido van Rossume7b146f2000-02-04 15:28:42 +0000381 def getcomptype(self):
382 return self._comptype
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000383
Guido van Rossume7b146f2000-02-04 15:28:42 +0000384 def getcompname(self):
385 return self._compname
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000386
Guido van Rossume7b146f2000-02-04 15:28:42 +0000387 def setparams(self, (nchannels, sampwidth, framerate, nframes, comptype, compname)):
388 if self._datawritten:
389 raise Error, 'cannot change parameters after starting to write'
390 self.setnchannels(nchannels)
391 self.setsampwidth(sampwidth)
392 self.setframerate(framerate)
393 self.setnframes(nframes)
394 self.setcomptype(comptype, compname)
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000395
Guido van Rossume7b146f2000-02-04 15:28:42 +0000396 def getparams(self):
397 if not self._nchannels or not self._sampwidth or not self._framerate:
398 raise Error, 'not all parameters set'
399 return self._nchannels, self._sampwidth, self._framerate, \
400 self._nframes, self._comptype, self._compname
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000401
Guido van Rossume7b146f2000-02-04 15:28:42 +0000402 def setmark(self, id, pos, name):
403 raise Error, 'setmark() not supported'
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000404
Guido van Rossume7b146f2000-02-04 15:28:42 +0000405 def getmark(self, id):
406 raise Error, 'no marks'
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000407
Guido van Rossume7b146f2000-02-04 15:28:42 +0000408 def getmarkers(self):
409 return None
Tim Peterse1190062001-01-15 03:34:38 +0000410
Guido van Rossume7b146f2000-02-04 15:28:42 +0000411 def tell(self):
412 return self._nframeswritten
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000413
Guido van Rossume7b146f2000-02-04 15:28:42 +0000414 def writeframesraw(self, data):
415 self._ensure_header_written(len(data))
Guido van Rossum54e54c62001-09-04 19:14:14 +0000416 nframes = len(data) // (self._sampwidth * self._nchannels)
Guido van Rossume7b146f2000-02-04 15:28:42 +0000417 if self._convert:
418 data = self._convert(data)
419 if self._sampwidth > 1 and big_endian:
420 import array
421 data = array.array(_array_fmts[self._sampwidth], data)
422 data.byteswap()
423 data.tofile(self._file)
424 self._datawritten = self._datawritten + len(data) * self._sampwidth
425 else:
426 self._file.write(data)
427 self._datawritten = self._datawritten + len(data)
428 self._nframeswritten = self._nframeswritten + nframes
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000429
Guido van Rossume7b146f2000-02-04 15:28:42 +0000430 def writeframes(self, data):
431 self.writeframesraw(data)
432 if self._datalength != self._datawritten:
433 self._patchheader()
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000434
Guido van Rossume7b146f2000-02-04 15:28:42 +0000435 def close(self):
Tim Peterscfc41782000-10-09 23:43:55 +0000436 if self._file:
437 self._ensure_header_written(0)
438 if self._datalength != self._datawritten:
439 self._patchheader()
440 self._file.flush()
441 self._file = None
442 if self._i_opened_the_file:
443 self._i_opened_the_file.close()
444 self._i_opened_the_file = None
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000445
Guido van Rossume7b146f2000-02-04 15:28:42 +0000446 #
447 # Internal methods.
448 #
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000449
Guido van Rossume7b146f2000-02-04 15:28:42 +0000450 def _ensure_header_written(self, datasize):
451 if not self._datawritten:
452 if not self._nchannels:
453 raise Error, '# channels not specified'
454 if not self._sampwidth:
455 raise Error, 'sample width not specified'
456 if not self._framerate:
457 raise Error, 'sampling rate not specified'
458 self._write_header(datasize)
459
460 def _write_header(self, initlength):
461 self._file.write('RIFF')
462 if not self._nframes:
463 self._nframes = initlength / (self._nchannels * self._sampwidth)
464 self._datalength = self._nframes * self._nchannels * self._sampwidth
465 self._form_length_pos = self._file.tell()
Guido van Rossumeca576c2000-10-09 20:01:53 +0000466 self._file.write(struct.pack('<l4s4slhhllhh4s',
Guido van Rossume7b146f2000-02-04 15:28:42 +0000467 36 + self._datalength, 'WAVE', 'fmt ', 16,
468 WAVE_FORMAT_PCM, self._nchannels, self._framerate,
469 self._nchannels * self._framerate * self._sampwidth,
470 self._nchannels * self._sampwidth,
471 self._sampwidth * 8, 'data'))
472 self._data_length_pos = self._file.tell()
473 self._file.write(struct.pack('<l', self._datalength))
474
475 def _patchheader(self):
476 if self._datawritten == self._datalength:
477 return
478 curpos = self._file.tell()
479 self._file.seek(self._form_length_pos, 0)
480 self._file.write(struct.pack('<l', 36 + self._datawritten))
481 self._file.seek(self._data_length_pos, 0)
482 self._file.write(struct.pack('<l', self._datawritten))
483 self._file.seek(curpos, 0)
484 self._datalength = self._datawritten
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000485
Fred Drakef9607821999-06-17 15:18:47 +0000486def open(f, mode=None):
Guido van Rossume7b146f2000-02-04 15:28:42 +0000487 if mode is None:
488 if hasattr(f, 'mode'):
489 mode = f.mode
490 else:
491 mode = 'rb'
492 if mode in ('r', 'rb'):
493 return Wave_read(f)
494 elif mode in ('w', 'wb'):
495 return Wave_write(f)
496 else:
497 raise Error, "mode must be 'r', 'rb', 'w', or 'wb'"
Guido van Rossum3ed23cc1994-02-15 15:57:15 +0000498
499openfp = open # B/W compatibility