diff -r ffa851df0825 -r 2fb8b9db1c86 symbian-qemu-0.9.1-12/python-2.6.1/Lib/aifc.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/symbian-qemu-0.9.1-12/python-2.6.1/Lib/aifc.py	Fri Jul 31 15:01:17 2009 +0100
@@ -0,0 +1,962 @@
+"""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 position 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__
+
+__all__ = ["Error","open","openfp"]
+
+class Error(Exception):
+    pass
+
+_AIFC_version = 0xA2805140L     # 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
+    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):
+    if len(s) > 255:
+        raise ValueError("string exceeds maximum pstring length")
+    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)
+
+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_ulong(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 %r does not exist' % (id,)
+
+    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.seek(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, info):
+        nchannels, sampwidth, framerate, nframes, comptype, compname = info
+        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 %r does not exist' % (id,)
+
+    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
+        dummy = self._comp.SetParam(cl.FRAME_BUFFER_SIZE, len(data))
+        dummy = 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':
+            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'"
+
+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."