summaryrefslogtreecommitdiffstats
path: root/Lib/aifc.py
blob: c317c5f14579f6820e738ff0302830f0450f4c65 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
# Stuff to parse AIFF-C and AIFF files.
#
# Unless explicitly stated otherwise, the description below is true
# both for AIFF-C files and AIFF files.
#
# An AIFF-C file has the following structure.
#
#	+-----------------+
#	| FORM            |
#	+-----------------+
#	| <size>          |
#	+----+------------+
#	|    | AIFC       |
#	|    +------------+
#	|    | <chunks>   |
#	|    |    .       |
#	|    |    .       |
#	|    |    .       |
#	+----+------------+
#
# An AIFF file has the string "AIFF" instead of "AIFC".
#
# A chunk consists of an identifier (4 bytes) followed by a size (4 bytes,
# big endian order), followed by the data.  The size field does not include
# the size of the 8 byte header.
#
# The following chunk types are recognized.
#
#	FVER
#		<version number of AIFF-C defining document> (AIFF-C only).
#	MARK
#		<# of markers> (2 bytes)
#		list of markers:
#			<marker ID> (2 bytes, must be > 0)
#			<position> (4 bytes)
#			<marker name> ("pstring")
#	COMM
#		<# of channels> (2 bytes)
#		<# of sound frames> (4 bytes)
#		<size of the samples> (2 bytes)
#		<sampling frequency> (10 bytes, IEEE 80-bit extended
#			floating point)
#		in AIFF-C files only:
#		<compression type> (4 bytes)
#		<human-readable version of compression type> ("pstring")
#	SSND
#		<offset> (4 bytes, not used by this program)
#		<blocksize> (4 bytes, not used by this program)
#		<sound data>
#
# A pstring consists of 1 byte length, a string of characters, and 0 or 1
# byte pad to make the total length even.
#
# Usage.
#
# Reading AIFF files:
#	f = aifc.open(file, 'r')
# where file is either the name of a file or an open file pointer.
# The open file pointer must have methods read(), seek(), and close().
# In some types of audio files, if the setpos() method is not used,
# the seek() method is not necessary.
#
# This returns an instance of a class with the following public methods:
#	getnchannels()	-- returns number of audio channels (1 for
#			   mono, 2 for stereo)
#	getsampwidth()	-- returns sample width in bytes
#	getframerate()	-- returns sampling frequency
#	getnframes()	-- returns number of audio frames
#	getcomptype()	-- returns compression type ('NONE' for AIFF files)
#	getcompname()	-- returns human-readable version of
#			   compression type ('not compressed' for AIFF files)
#	getparams()	-- returns a tuple consisting of all of the
#			   above in the above order
#	getmarkers()	-- get the list of marks in the audio file or None
#			   if there are no marks
#	getmark(id)	-- get mark with the specified id (raises an error
#			   if the mark does not exist)
#	readframes(n)	-- returns at most n frames of audio
#	rewind()	-- rewind to the beginning of the audio stream
#	setpos(pos)	-- seek to the specified position
#	tell()		-- return the current position
#	close()		-- close the instance (make it unusable)
# The position returned by tell(), the position given to setpos() and
# the position of marks are all compatible and have nothing to do with
# the actual postion in the file.
# The close() method is called automatically when the class instance
# is destroyed.
#
# Writing AIFF files:
#	f = aifc.open(file, 'w')
# where file is either the name of a file or an open file pointer.
# The open file pointer must have methods write(), tell(), seek(), and
# close().
#
# This returns an instance of a class with the following public methods:
#	aiff()		-- create an AIFF file (AIFF-C default)
#	aifc()		-- create an AIFF-C file
#	setnchannels(n)	-- set the number of channels
#	setsampwidth(n)	-- set the sample width
#	setframerate(n)	-- set the frame rate
#	setnframes(n)	-- set the number of frames
#	setcomptype(type, name)
#			-- set the compression type and the
#			   human-readable compression type
#	setparams(tuple)
#			-- set all parameters at once
#	setmark(id, pos, name)
#			-- add specified mark to the list of marks
#	tell()		-- return current position in output file (useful
#			   in combination with setmark())
#	writeframesraw(data)
#			-- write audio frames without pathing up the
#			   file header
#	writeframes(data)
#			-- write audio frames and patch up the file header
#	close()		-- patch up the file header and close the
#			   output file
# You should set the parameters before the first writeframesraw or
# writeframes.  The total number of frames does not need to be set,
# but when it is set to the correct value, the header does not have to
# be patched up.
# It is best to first set all parameters, perhaps possibly the
# compression type, and then write audio frames using writeframesraw.
# When all frames have been written, either call writeframes('') or
# close() to patch up the sizes in the header.
# Marks can be added anytime.  If there are any marks, ypu must call
# close() after all frames have been written.
# The close() method is called automatically when the class instance
# is destroyed.
#
# When a file is opened with the extension '.aiff', an AIFF file is
# written, otherwise an AIFF-C file is written.  This default can be
# changed by calling aiff() or aifc() before the first writeframes or
# writeframesraw.

import struct
import __builtin__

Error = 'aifc.Error'

_AIFC_version = 0xA2805140		# Version 1 of AIFF-C

_skiplist = 'COMT', 'INST', 'MIDI', 'AESD', \
	  'APPL', 'NAME', 'AUTH', '(c) ', 'ANNO'

def _read_long(file):
	try:
		return struct.unpack('>l', file.read(4))[0]
	except struct.error:
		raise EOFError

def _read_ulong(file):
	try:
		return struct.unpack('>L', file.read(4))[0]
	except struct.error:
		raise EOFError

def _read_short(file):
	try:
		return struct.unpack('>h', file.read(2))[0]
	except struct.error:
		raise EOFError

def _read_string(file):
	length = ord(file.read(1))
	if length == 0:
		data = ''
	else:
		data = file.read(length)
	if length & 1 == 0:
		dummy = file.read(1)
	return data

_HUGE_VAL = 1.79769313486231e+308 # See <limits.h>

def _read_float(f): # 10 bytes
	import math
	expon = _read_short(f) # 2 bytes
	sign = 1
	if expon < 0:
		sign = -1
		expon = expon + 0x8000
	himant = _read_ulong(f) # 4 bytes
	lomant = _read_ulong(f) # 4 bytes
	if expon == himant == lomant == 0:
		f = 0.0
	elif expon == 0x7FFF:
		f = _HUGE_VAL
	else:
		expon = expon - 16383
		f = (himant * 0x100000000L + lomant) * pow(2.0, expon - 63)
	return sign * f

def _write_short(f, x):
	f.write(struct.pack('>h', x))

def _write_long(f, x):
	f.write(struct.pack('>L', x))

def _write_string(f, s):
	f.write(chr(len(s)))
	f.write(s)
	if len(s) & 1 == 0:
		f.write(chr(0))

def _write_float(f, x):
	import math
	if x < 0:
		sign = 0x8000
		x = x * -1
	else:
		sign = 0
	if x == 0:
		expon = 0
		himant = 0
		lomant = 0
	else:
		fmant, expon = math.frexp(x)
		if expon > 16384 or fmant >= 1:		# Infinity or NaN
			expon = sign|0x7FFF
			himant = 0
			lomant = 0
		else:					# Finite
			expon = expon + 16382
			if expon < 0:			# denormalized
				fmant = math.ldexp(fmant, expon)
				expon = 0
			expon = expon | sign
			fmant = math.ldexp(fmant, 32)
			fsmant = math.floor(fmant)
			himant = long(fsmant)
			fmant = math.ldexp(fmant - fsmant, 32)
			fsmant = math.floor(fmant)
			lomant = long(fsmant)
	_write_short(f, expon)
	_write_long(f, himant)
	_write_long(f, lomant)

class Chunk:
	def __init__(self, file):
		self.file = file
		self.chunkname = self.file.read(4)
		if len(self.chunkname) < 4:
			raise EOFError
		self.chunksize = _read_long(self.file)
		self.size_read = 0
		self.offset = self.file.tell()

	def rewind(self):
		self.file.seek(self.offset, 0)
		self.size_read = 0

	def setpos(self, pos):
		if pos < 0 or pos > self.chunksize:
			raise RuntimeError
		self.file.seek(self.offset + pos, 0)
		self.size_read = pos
		
	def read(self, length):
		if self.size_read >= self.chunksize:
			return ''
		if length > self.chunksize - self.size_read:
 			length = self.chunksize - self.size_read
		data = self.file.read(length)
		self.size_read = self.size_read + len(data)
		return data

	def skip(self):
		try:
			self.file.seek(self.chunksize - self.size_read, 1)
		except RuntimeError:
			while self.size_read < self.chunksize:
				dummy = self.read(8192)
				if not dummy:
					raise EOFError
		if self.chunksize & 1:
			dummy = self.read(1)

class Aifc_read:
	# Variables used in this class:
	#
	# These variables are available to the user though appropriate
	# methods of this class:
	# _file -- the open file with methods read(), close(), and seek()
	#		set through the __init__() method
	# _nchannels -- the number of audio channels
	#		available through the getnchannels() method
	# _nframes -- the number of audio frames
	#		available through the getnframes() method
	# _sampwidth -- the number of bytes per audio sample
	#		available through the getsampwidth() method
	# _framerate -- the sampling frequency
	#		available through the getframerate() method
	# _comptype -- the AIFF-C compression type ('NONE' if AIFF)
	#		available through the getcomptype() method
	# _compname -- the human-readable AIFF-C compression type
	#		available through the getcomptype() method
	# _markers -- the marks in the audio file
	#		available through the getmarkers() and getmark()
	#		methods
	# _soundpos -- the position in the audio stream
	#		available through the tell() method, set through the
	#		setpos() method
	#
	# These variables are used internally only:
	# _version -- the AIFF-C version number
	# _decomp -- the decompressor from builtin module cl
	# _comm_chunk_read -- 1 iff the COMM chunk has been read
	# _aifc -- 1 iff reading an AIFF-C file
	# _ssnd_seek_needed -- 1 iff positioned correctly in audio
	#		file for readframes()
	# _ssnd_chunk -- instantiation of a chunk class for the SSND chunk
	# _framesize -- size of one frame in the file

## 	if 0: access _file, _nchannels, _nframes, _sampwidth, _framerate, \
## 		  _comptype, _compname, _markers, _soundpos, _version, \
## 		  _decomp, _comm_chunk_read, __aifc, _ssnd_seek_needed, \
## 		  _ssnd_chunk, _framesize: private

	def initfp(self, file):
		self._file = file
		self._version = 0
		self._decomp = None
		self._convert = None
		self._markers = []
		self._soundpos = 0
		form = self._file.read(4)
		if form != 'FORM':
			raise Error, 'file does not start with FORM id'
		formlength = _read_long(self._file)
		if formlength <= 0:
			raise Error, 'invalid FORM chunk data size'
		formdata = self._file.read(4)
		formlength = formlength - 4
		if formdata == 'AIFF':
			self._aifc = 0
		elif formdata == 'AIFC':
			self._aifc = 1
		else:
			raise Error, 'not an AIFF or AIFF-C file'
		self._comm_chunk_read = 0
		while formlength > 0:
			self._ssnd_seek_needed = 1
			#DEBUG: SGI's soundfiler has a bug.  There should
			# be no need to check for EOF here.
			try:
				chunk = Chunk(self._file)
			except EOFError:
				if formlength == 8:
					print 'Warning: FORM chunk size too large'
					formlength = 0
					break
				raise EOFError # different error, raise exception
			if chunk.chunkname == 'COMM':
				self._read_comm_chunk(chunk)
				self._comm_chunk_read = 1
			elif chunk.chunkname == 'SSND':
				self._ssnd_chunk = chunk
				dummy = chunk.read(8)
				self._ssnd_seek_needed = 0
			elif chunk.chunkname == 'FVER':
				self._version = _read_long(chunk)
			elif chunk.chunkname == 'MARK':
				self._readmark(chunk)
			elif chunk.chunkname in _skiplist:
				pass
			else:
				raise Error, 'unrecognized chunk type '+chunk.chunkname
			formlength = formlength - 8 - chunk.chunksize
			if chunk.chunksize & 1:
				formlength = formlength - 1
			if formlength > 0:
				chunk.skip()
		if not self._comm_chunk_read or not self._ssnd_chunk:
			raise Error, 'COMM chunk and/or SSND chunk missing'
		if self._aifc and self._decomp:
			import cl
			params = [cl.ORIGINAL_FORMAT, 0,
				  cl.BITS_PER_COMPONENT, self._sampwidth * 8,
				  cl.FRAME_RATE, self._framerate]
			if self._nchannels == 1:
				params[1] = cl.MONO
			elif self._nchannels == 2:
				params[1] = cl.STEREO_INTERLEAVED
			else:
				raise Error, 'cannot compress more than 2 channels'
			self._decomp.SetParams(params)

	def __init__(self, f):
		if type(f) == type(''):
			f = __builtin__.open(f, 'rb')
		# else, assume it is an open file object already
		self.initfp(f)

	def __del__(self):
		if self._file:
			self.close()

	#
	# User visible methods.
	#
	def getfp(self):
		return self._file

	def rewind(self):
		self._ssnd_seek_needed = 1
		self._soundpos = 0

	def close(self):
		if self._decomp:
			self._decomp.CloseDecompressor()
			self._decomp = None
		self._file = None

	def tell(self):
		return self._soundpos

	def getnchannels(self):
		return self._nchannels

	def getnframes(self):
		return self._nframes

	def getsampwidth(self):
		return self._sampwidth

	def getframerate(self):
		return self._framerate

	def getcomptype(self):
		return self._comptype

	def getcompname(self):
		return self._compname

##	def getversion(self):
##		return self._version

	def getparams(self):
		return self.getnchannels(), self.getsampwidth(), \
			  self.getframerate(), self.getnframes(), \
			  self.getcomptype(), self.getcompname()

	def getmarkers(self):
		if len(self._markers) == 0:
			return None
		return self._markers

	def getmark(self, id):
		for marker in self._markers:
			if id == marker[0]:
				return marker
		raise Error, 'marker ' + `id` + ' does not exist'

	def setpos(self, pos):
		if pos < 0 or pos > self._nframes:
			raise Error, 'position not in range'
		self._soundpos = pos
		self._ssnd_seek_needed = 1

	def readframes(self, nframes):
		if self._ssnd_seek_needed:
			self._ssnd_chunk.rewind()
			dummy = self._ssnd_chunk.read(8)
			pos = self._soundpos * self._framesize
			if pos:
				self._ssnd_chunk.setpos(pos + 8)
			self._ssnd_seek_needed = 0
		if nframes == 0:
			return ''
		data = self._ssnd_chunk.read(nframes * self._framesize)
		if self._convert and data:
			data = self._convert(data)
		self._soundpos = self._soundpos + len(data) / (self._nchannels * self._sampwidth)
		return data

	#
	# Internal methods.
	#
## 	if 0: access *: private

	def _decomp_data(self, data):
		import cl
		dummy = self._decomp.SetParam(cl.FRAME_BUFFER_SIZE,
					      len(data) * 2)
		return self._decomp.Decompress(len(data) / self._nchannels,
					       data)

	def _ulaw2lin(self, data):
		import audioop
		return audioop.ulaw2lin(data, 2)

	def _adpcm2lin(self, data):
		import audioop
		if not hasattr(self, '_adpcmstate'):
			# first time
			self._adpcmstate = None
		data, self._adpcmstate = audioop.adpcm2lin(data, 2,
							   self._adpcmstate)
		return data

	def _read_comm_chunk(self, chunk):
		self._nchannels = _read_short(chunk)
		self._nframes = _read_long(chunk)
		self._sampwidth = (_read_short(chunk) + 7) / 8
		self._framerate = int(_read_float(chunk))
		self._framesize = self._nchannels * self._sampwidth
		if self._aifc:
			#DEBUG: SGI's soundeditor produces a bad size :-(
			kludge = 0
			if chunk.chunksize == 18:
				kludge = 1
				print 'Warning: bad COMM chunk size'
				chunk.chunksize = 23
			#DEBUG end
			self._comptype = chunk.read(4)
			#DEBUG start
			if kludge:
				length = ord(chunk.file.read(1))
				if length & 1 == 0:
					length = length + 1
				chunk.chunksize = chunk.chunksize + length
				chunk.file.seek(-1, 1)
			#DEBUG end
			self._compname = _read_string(chunk)
			if self._comptype != 'NONE':
				if self._comptype == 'G722':
					try:
						import audioop
					except ImportError:
						pass
					else:
						self._convert = self._adpcm2lin
						self._framesize = self._framesize / 4
						return
				# for ULAW and ALAW try Compression Library
				try:
					import cl
				except ImportError:
					if self._comptype == 'ULAW':
						try:
							import audioop
							self._convert = self._ulaw2lin
							self._framesize = self._framesize / 2
							return
						except ImportError:
							pass
					raise Error, 'cannot read compressed AIFF-C files'
				if self._comptype == 'ULAW':
					scheme = cl.G711_ULAW
					self._framesize = self._framesize / 2
				elif self._comptype == 'ALAW':
					scheme = cl.G711_ALAW
					self._framesize = self._framesize / 2
				else:
					raise Error, 'unsupported compression type'
				self._decomp = cl.OpenDecompressor(scheme)
				self._convert = self._decomp_data
		else:
			self._comptype = 'NONE'
			self._compname = 'not compressed'

	def _readmark(self, chunk):
		nmarkers = _read_short(chunk)
		# Some files appear to contain invalid counts.
		# Cope with this by testing for EOF.
		try:
			for i in range(nmarkers):
				id = _read_short(chunk)
				pos = _read_long(chunk)
				name = _read_string(chunk)
				if pos or name:
					# some files appear to have
					# dummy markers consisting of
					# a position 0 and name ''
					self._markers.append((id, pos, name))
		except EOFError:
			print 'Warning: MARK chunk contains only',
			print len(self._markers),
			if len(self._markers) == 1: print 'marker',
			else: print 'markers',
			print 'instead of', nmarkers

class Aifc_write:
	# Variables used in this class:
	#
	# These variables are user settable through appropriate methods
	# of this class:
	# _file -- the open file with methods write(), close(), tell(), seek()
	#		set through the __init__() method
	# _comptype -- the AIFF-C compression type ('NONE' in AIFF)
	#		set through the setcomptype() or setparams() method
	# _compname -- the human-readable AIFF-C compression type
	#		set through the setcomptype() or setparams() method
	# _nchannels -- the number of audio channels
	#		set through the setnchannels() or setparams() method
	# _sampwidth -- the number of bytes per audio sample
	#		set through the setsampwidth() or setparams() method
	# _framerate -- the sampling frequency
	#		set through the setframerate() or setparams() method
	# _nframes -- the number of audio frames written to the header
	#		set through the setnframes() or setparams() method
	# _aifc -- whether we're writing an AIFF-C file or an AIFF file
	#		set through the aifc() method, reset through the
	#		aiff() method
	#
	# These variables are used internally only:
	# _version -- the AIFF-C version number
	# _comp -- the compressor from builtin module cl
	# _nframeswritten -- the number of audio frames actually written
	# _datalength -- the size of the audio samples written to the header
	# _datawritten -- the size of the audio samples actually written

## 	if 0: access _file, _comptype, _compname, _nchannels, _sampwidth, \
## 		  _framerate, _nframes, _aifc, _version, _comp, \
## 		  _nframeswritten, _datalength, _datawritten: private

	def __init__(self, f):
		if type(f) == type(''):
			filename = f
			f = __builtin__.open(f, 'wb')
		else:
			# else, assume it is an open file object already
			filename = '???'
		self.initfp(f)
		if filename[-5:] == '.aiff':
			self._aifc = 0
		else:
			self._aifc = 1

	def initfp(self, file):
		self._file = file
		self._version = _AIFC_version
		self._comptype = 'NONE'
		self._compname = 'not compressed'
		self._comp = None
		self._convert = None
		self._nchannels = 0
		self._sampwidth = 0
		self._framerate = 0
		self._nframes = 0
		self._nframeswritten = 0
		self._datawritten = 0
		self._datalength = 0
		self._markers = []
		self._marklength = 0
		self._aifc = 1		# AIFF-C is default

	def __del__(self):
		if self._file:
			self.close()

	#
	# User visible methods.
	#
	def aiff(self):
		if self._nframeswritten:
			raise Error, 'cannot change parameters after starting to write'
		self._aifc = 0

	def aifc(self):
		if self._nframeswritten:
			raise Error, 'cannot change parameters after starting to write'
		self._aifc = 1

	def setnchannels(self, nchannels):
		if self._nframeswritten:
			raise Error, 'cannot change parameters after starting to write'
		if nchannels < 1:
			raise Error, 'bad # of channels'
		self._nchannels = nchannels

	def getnchannels(self):
		if not self._nchannels:
			raise Error, 'number of channels not set'
		return self._nchannels

	def setsampwidth(self, sampwidth):
		if self._nframeswritten:
			raise Error, 'cannot change parameters after starting to write'
		if sampwidth < 1 or sampwidth > 4:
			raise Error, 'bad sample width'
		self._sampwidth = sampwidth

	def getsampwidth(self):
		if not self._sampwidth:
			raise Error, 'sample width not set'
		return self._sampwidth

	def setframerate(self, framerate):
		if self._nframeswritten:
			raise Error, 'cannot change parameters after starting to write'
		if framerate <= 0:
			raise Error, 'bad frame rate'
		self._framerate = framerate

	def getframerate(self):
		if not self._framerate:
			raise Error, 'frame rate not set'
		return self._framerate

	def setnframes(self, nframes):
		if self._nframeswritten:
			raise Error, 'cannot change parameters after starting to write'
		self._nframes = nframes

	def getnframes(self):
		return self._nframeswritten

	def setcomptype(self, comptype, compname):
		if self._nframeswritten:
			raise Error, 'cannot change parameters after starting to write'
		if comptype not in ('NONE', 'ULAW', 'ALAW', 'G722'):
			raise Error, 'unsupported compression type'
		self._comptype = comptype
		self._compname = compname

	def getcomptype(self):
		return self._comptype

	def getcompname(self):
		return self._compname

##	def setversion(self, version):
##		if self._nframeswritten:
##			raise Error, 'cannot change parameters after starting to write'
##		self._version = version

	def setparams(self, (nchannels, sampwidth, framerate, nframes, comptype, compname)):
		if self._nframeswritten:
			raise Error, 'cannot change parameters after starting to write'
		if comptype not in ('NONE', 'ULAW', 'ALAW', 'G722'):
			raise Error, 'unsupported compression type'
		self.setnchannels(nchannels)
		self.setsampwidth(sampwidth)
		self.setframerate(framerate)
		self.setnframes(nframes)
		self.setcomptype(comptype, compname)

	def getparams(self):
		if not self._nchannels or not self._sampwidth or not self._framerate:
			raise Error, 'not all parameters set'
		return self._nchannels, self._sampwidth, self._framerate, \
			  self._nframes, self._comptype, self._compname

	def setmark(self, id, pos, name):
		if id <= 0:
			raise Error, 'marker ID must be > 0'
		if pos < 0:
			raise Error, 'marker position must be >= 0'
		if type(name) != type(''):
			raise Error, 'marker name must be a string'
		for i in range(len(self._markers)):
			if id == self._markers[i][0]:
				self._markers[i] = id, pos, name
				return
		self._markers.append((id, pos, name))

	def getmark(self, id):
		for marker in self._markers:
			if id == marker[0]:
				return marker
		raise Error, 'marker ' + `id` + ' does not exist'

	def getmarkers(self):
		if len(self._markers) == 0:
			return None
		return self._markers
				
	def tell(self):
		return self._nframeswritten

	def writeframesraw(self, data):
		self._ensure_header_written(len(data))
		nframes = len(data) / (self._sampwidth * self._nchannels)
		if self._convert:
			data = self._convert(data)
		self._file.write(data)
		self._nframeswritten = self._nframeswritten + nframes
		self._datawritten = self._datawritten + len(data)

	def writeframes(self, data):
		self.writeframesraw(data)
		if self._nframeswritten != self._nframes or \
			  self._datalength != self._datawritten:
			self._patchheader()

	def close(self):
		self._ensure_header_written(0)
		if self._datawritten & 1:
			# quick pad to even size
			self._file.write(chr(0))
			self._datawritten = self._datawritten + 1
		self._writemarkers()
		if self._nframeswritten != self._nframes or \
			  self._datalength != self._datawritten or \
			  self._marklength:
			self._patchheader()
		if self._comp:
			self._comp.CloseCompressor()
			self._comp = None
		self._file.flush()
		self._file = None

	#
	# Internal methods.
	#
## 	if 0: access *: private

	def _comp_data(self, data):
		import cl
		dum = self._comp.SetParam(cl.FRAME_BUFFER_SIZE, len(data))
		dum = self._comp.SetParam(cl.COMPRESSED_BUFFER_SIZE, len(data))
		return self._comp.Compress(self._nframes, data)

	def _lin2ulaw(self, data):
		import audioop
		return audioop.lin2ulaw(data, 2)

	def _lin2adpcm(self, data):
		import audioop
		if not hasattr(self, '_adpcmstate'):
			self._adpcmstate = None
		data, self._adpcmstate = audioop.lin2adpcm(data, 2,
							   self._adpcmstate)
		return data

	def _ensure_header_written(self, datasize):
		if not self._nframeswritten:
			if self._comptype in ('ULAW', 'ALAW'):
				if not self._sampwidth:
					self._sampwidth = 2
				if self._sampwidth != 2:
					raise Error, 'sample width must be 2 when compressing with ULAW or ALAW'
			if self._comptype == 'G722':
				if not self._sampwidth:
					self._sampwidth = 2
				if self._sampwidth != 2:
					raise Error, 'sample width must be 2 when compressing with G7.22 (ADPCM)'
			if not self._nchannels:
				raise Error, '# channels not specified'
			if not self._sampwidth:
				raise Error, 'sample width not specified'
			if not self._framerate:
				raise Error, 'sampling rate not specified'
			self._write_header(datasize)

	def _init_compression(self):
		if self._comptype == 'G722':
			import audioop
			self._convert = self._lin2adpcm
			return
		try:
			import cl
		except ImportError:
			if self._comptype == 'ULAW':
				try:
					import audioop
					self._convert = self._lin2ulaw
					return
				except ImportError:
					pass
			raise Error, 'cannot write compressed AIFF-C files'
		if self._comptype == 'ULAW':
			scheme = cl.G711_ULAW
		elif self._comptype == 'ALAW':
			scheme = cl.G711_ALAW
		else:
			raise Error, 'unsupported compression type'
		self._comp = cl.OpenCompressor(scheme)
		params = [cl.ORIGINAL_FORMAT, 0,
			  cl.BITS_PER_COMPONENT, self._sampwidth * 8,
			  cl.FRAME_RATE, self._framerate,
			  cl.FRAME_BUFFER_SIZE, 100,
			  cl.COMPRESSED_BUFFER_SIZE, 100]
		if self._nchannels == 1:
			params[1] = cl.MONO
		elif self._nchannels == 2:
			params[1] = cl.STEREO_INTERLEAVED
		else:
			raise Error, 'cannot compress more than 2 channels'
		self._comp.SetParams(params)
		# the compressor produces a header which we ignore
		dummy = self._comp.Compress(0, '')
		self._convert = self._comp_data

	def _write_header(self, initlength):
		if self._aifc and self._comptype != 'NONE':
			self._init_compression()
		self._file.write('FORM')
		if not self._nframes:
			self._nframes = initlength / (self._nchannels * self._sampwidth)
		self._datalength = self._nframes * self._nchannels * self._sampwidth
		if self._datalength & 1:
			self._datalength = self._datalength + 1
		if self._aifc:
			if self._comptype in ('ULAW', 'ALAW'):
				self._datalength = self._datalength / 2
				if self._datalength & 1:
					self._datalength = self._datalength + 1
			elif self._comptype == 'G722':
				self._datalength = (self._datalength + 3) / 4
				if self._datalength & 1:
					self._datalength = self._datalength + 1
		self._form_length_pos = self._file.tell()
		commlength = self._write_form_length(self._datalength)
		if self._aifc:
			self._file.write('AIFC')
			self._file.write('FVER')
			_write_long(self._file, 4)
			_write_long(self._file, self._version)
		else:
			self._file.write('AIFF')
		self._file.write('COMM')
		_write_long(self._file, commlength)
		_write_short(self._file, self._nchannels)
		self._nframes_pos = self._file.tell()
		_write_long(self._file, self._nframes)
		_write_short(self._file, self._sampwidth * 8)
		_write_float(self._file, self._framerate)
		if self._aifc:
			self._file.write(self._comptype)
			_write_string(self._file, self._compname)
		self._file.write('SSND')
		self._ssnd_length_pos = self._file.tell()
		_write_long(self._file, self._datalength + 8)
		_write_long(self._file, 0)
		_write_long(self._file, 0)

	def _write_form_length(self, datalength):
		if self._aifc:
			commlength = 18 + 5 + len(self._compname)
			if commlength & 1:
				commlength = commlength + 1
			verslength = 12
		else:
			commlength = 18
			verslength = 0
		_write_long(self._file, 4 + verslength + self._marklength + \
					8 + commlength + 16 + datalength)
		return commlength

	def _patchheader(self):
		curpos = self._file.tell()
		if self._datawritten & 1:
			datalength = self._datawritten + 1
			self._file.write(chr(0))
		else:
			datalength = self._datawritten
		if datalength == self._datalength and \
			  self._nframes == self._nframeswritten and \
			  self._marklength == 0:
			self._file.seek(curpos, 0)
			return
		self._file.seek(self._form_length_pos, 0)
		dummy = self._write_form_length(datalength)
		self._file.seek(self._nframes_pos, 0)
		_write_long(self._file, self._nframeswritten)
		self._file.seek(self._ssnd_length_pos, 0)
		_write_long(self._file, datalength + 8)
		self._file.seek(curpos, 0)
		self._nframes = self._nframeswritten
		self._datalength = datalength

	def _writemarkers(self):
		if len(self._markers) == 0:
			return
		self._file.write('MARK')
		length = 2
		for marker in self._markers:
			id, pos, name = marker
			length = length + len(name) + 1 + 6
			if len(name) & 1 == 0:
				length = length + 1
		_write_long(self._file, length)
		self._marklength = length + 8
		_write_short(self._file, len(self._markers))
		for marker in self._markers:
			id, pos, name = marker
			_write_short(self._file, id)
			_write_long(self._file, pos)
			_write_string(self._file, name)

def open(f, mode):
	if mode == 'r':
		return Aifc_read(f)
	elif mode == 'w':
		return Aifc_write(f)
	else:
		raise Error, "mode must be 'r' or 'w'"

openfp = open # B/W compatibility

if __name__ == '__main__':
	import sys
	if not sys.argv[1:]:
		sys.argv.append('/usr/demos/data/audio/bach.aiff')
	fn = sys.argv[1]
	f = open(fn, 'r')
	print "Reading", fn
	print "nchannels =", f.getnchannels()
	print "nframes   =", f.getnframes()
	print "sampwidth =", f.getsampwidth()
	print "framerate =", f.getframerate()
	print "comptype  =", f.getcomptype()
	print "compname  =", f.getcompname()
	if sys.argv[2:]:
		gn = sys.argv[2]
		print "Writing", gn
		g = open(gn, 'w')
		g.setparams(f.getparams())
		while 1:
			data = f.readframes(1024)
			if not data:
				break
			g.writeframes(data)
		g.close()
		f.close()
		print "Done."