Mass patch by Ka-Ping Yee:

    1. Comments at the beginning of the module, before
       functions, and before classes have been turned
       into docstrings.

    2. Tabs are normalized to four spaces.

Also, removed the "remove" function from dircmp.py, which reimplements
list.remove() (it must have been very old).

1 files changed, 918 insertions, 917 deletions

diff --git a/Lib/aifc.py b/Lib/aifc.py
index 6c19dea..f7288d5 100644
--- a/Lib/aifc.py
+++ b/Lib/aifc.py
@@ -1,957 +1,958 @@
-# 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.
+"""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
+_AIFC_version = 0xA2805140      # Version 1 of AIFF-C
 
 _skiplist = 'COMT', 'INST', 'MIDI', 'AESD', \
-	  'APPL', 'NAME', 'AUTH', '(c) ', 'ANNO'
+      'APPL', 'NAME', 'AUTH', '(c) ', 'ANNO'
 
 def _read_long(file):
-	try:
-		return struct.unpack('>l', file.read(4))[0]
-	except struct.error:
-		raise EOFError
+    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
+    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
+    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
+    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
+    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))
+    f.write(struct.pack('>h', x))
 
 def _write_long(f, x):
-	f.write(struct.pack('>L', 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))
+    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)
+    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)
 
 from chunk import Chunk
 
 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
-
-	def initfp(self, file):
-		self._version = 0
-		self._decomp = None
-		self._convert = None
-		self._markers = []
-		self._soundpos = 0
-		self._file = Chunk(file)
-		if self._file.getname() != 'FORM':
-			raise Error, 'file does not start with FORM id'
-		formdata = self._file.read(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 1:
-			self._ssnd_seek_needed = 1
-			try:
-				chunk = Chunk(self._file)
-			except EOFError:
-				break
-			chunkname = chunk.getname()
-			if chunkname == 'COMM':
-				self._read_comm_chunk(chunk)
-				self._comm_chunk_read = 1
-			elif chunkname == 'SSND':
-				self._ssnd_chunk = chunk
-				dummy = chunk.read(8)
-				self._ssnd_seek_needed = 0
-			elif chunkname == 'FVER':
-				self._version = _read_long(chunk)
-			elif chunkname == 'MARK':
-				self._readmark(chunk)
-			elif chunkname in _skiplist:
-				pass
-			else:
-				raise Error, 'unrecognized chunk type '+chunk.chunkname
-			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)
-
-	#
-	# 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.seek(0)
-			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.
-	#
-
-	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
+    # 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
+
+    def initfp(self, file):
+        self._version = 0
+        self._decomp = None
+        self._convert = None
+        self._markers = []
+        self._soundpos = 0
+        self._file = Chunk(file)
+        if self._file.getname() != 'FORM':
+            raise Error, 'file does not start with FORM id'
+        formdata = self._file.read(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 1:
+            self._ssnd_seek_needed = 1
+            try:
+                chunk = Chunk(self._file)
+            except EOFError:
+                break
+            chunkname = chunk.getname()
+            if chunkname == 'COMM':
+                self._read_comm_chunk(chunk)
+                self._comm_chunk_read = 1
+            elif chunkname == 'SSND':
+                self._ssnd_chunk = chunk
+                dummy = chunk.read(8)
+                self._ssnd_seek_needed = 0
+            elif chunkname == 'FVER':
+                self._version = _read_long(chunk)
+            elif chunkname == 'MARK':
+                self._readmark(chunk)
+            elif chunkname in _skiplist:
+                pass
+            else:
+                raise Error, 'unrecognized chunk type '+chunk.chunkname
+            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)
+
+    #
+    # 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.seek(0)
+            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.
+    #
+
+    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
-
-	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.
-	#
-
-	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)
+    # 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
+
+    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.
+    #
+
+    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=None):
-	if mode is None:
-		if hasattr(f, 'mode'):
-			mode = f.mode
-		else:
-			mode = 'rb'
-	if mode in ('r', 'rb'):
-		return Aifc_read(f)
-	elif mode in ('w', 'wb'):
-		return Aifc_write(f)
-	else:
-		raise Error, "mode must be 'r', 'rb', 'w', or 'wb'"
+    if mode is None:
+        if hasattr(f, 'mode'):
+            mode = f.mode
+        else:
+            mode = 'rb'
+    if mode in ('r', 'rb'):
+        return Aifc_read(f)
+    elif mode in ('w', 'wb'):
+        return Aifc_write(f)
+    else:
+        raise Error, "mode must be 'r', 'rb', 'w', or 'wb'"
 
 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."
+    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."