"""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 namedtuple 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(b'') or

close() to patch up the sizes in the header.

Marks can be added anytime. If there are any marks, you 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 builtins

import warnings

__all__ = ["Error", "open"]

warnings._deprecated(__name__, remove=(3, 13))

class Error(Exception):

pass

_AIFC_version = 0xA2805140 # Version 1 of AIFF-C

def _read_long(file):

try:

return struct.unpack('>l', file.read(4))[0]

except struct.error:

raise EOFError from None

def _read_ulong(file):

try:

return struct.unpack('>L', file.read(4))[0]

except struct.error:

raise EOFError from None

def _read_short(file):

try:

return struct.unpack('>h', file.read(2))[0]

except struct.error:

raise EOFError from None

def _read_ushort(file):

try:

return struct.unpack('>H', file.read(2))[0]

except struct.error:

raise EOFError from None

def _read_string(file):

length = ord(file.read(1))

if length == 0:

data = b''

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 * 0x100000000 + lomant) * pow(2.0, expon - 63)

return sign * f

def _write_short(f, x):

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

def _write_ushort(f, x):

f.write(struct.pack('>H', x))

def _write_long(f, x):

f.write(struct.pack('>l', x))

def _write_ulong(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(struct.pack('B', len(s)))

f.write(s)

if len(s) & 1 == 0:

f.write(b'\x00')

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 or fmant != fmant: # 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 = int(fsmant)

fmant = math.ldexp(fmant - fsmant, 32)

fsmant = math.floor(fmant)

lomant = int(fsmant)

_write_ushort(f, expon)

_write_ulong(f, himant)

_write_ulong(f, lomant)

with warnings.catch_warnings():

warnings.simplefilter("ignore", DeprecationWarning)

from chunk import Chunk

from collections import namedtuple

_aifc_params = namedtuple('_aifc_params',

'nchannels sampwidth framerate nframes comptype compname')

_aifc_params.nchannels.__doc__ = 'Number of audio channels (1 for mono, 2 for stereo)'

_aifc_params.sampwidth.__doc__ = 'Sample width in bytes'

_aifc_params.framerate.__doc__ = 'Sampling frequency'

_aifc_params.nframes.__doc__ = 'Number of audio frames'

_aifc_params.comptype.__doc__ = 'Compression type ("NONE" for AIFF files)'

_aifc_params.compname.__doc__ = ("""\

A human-readable version of the compression type

('not compressed' for AIFF files)""")

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

_file = None # Set here since __del__ checks it

def initfp(self, file):

self._version = 0

self._convert = None

self._markers = []

self._soundpos = 0

self._file = file

chunk = Chunk(file)

if chunk.getname() != b'FORM':

raise Error('file does not start with FORM id')

formdata = chunk.read(4)

if formdata == b'AIFF':

self._aifc = 0

elif formdata == b'AIFC':

self._aifc = 1

else:

raise Error('not an AIFF or AIFF-C file')

self._comm_chunk_read = 0

self._ssnd_chunk = None

while 1:

self._ssnd_seek_needed = 1

try:

chunk = Chunk(self._file)

except EOFError:

break

chunkname = chunk.getname()

if chunkname == b'COMM':

self._read_comm_chunk(chunk)

self._comm_chunk_read = 1

elif chunkname == b'SSND':

self._ssnd_chunk = chunk

dummy = chunk.read(8)

self._ssnd_seek_needed = 0

elif chunkname == b'FVER':

self._version = _read_ulong(chunk)

elif chunkname == b'MARK':

self._readmark(chunk)

chunk.skip()

if not self._comm_chunk_read or not self._ssnd_chunk:

raise Error('COMM chunk and/or SSND chunk missing')

def __init__(self, f):

if isinstance(f, str):

file_object = builtins.open(f, 'rb')

try:

self.initfp(file_object)

except:

file_object.close()

raise

else:

# assume it is an open file object already

self.initfp(f)

def __enter__(self):

return self

def __exit__(self, *args):

self.close()

#

# User visible methods.

#

def getfp(self):

return self._file

def rewind(self):

self._ssnd_seek_needed = 1

self._soundpos = 0

def close(self):

file = self._file

if file is not None:

self._file = None

file.close()

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 _aifc_params(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 {0!r} does not exist'.format(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 b''

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 _alaw2lin(self, data):

with warnings.catch_warnings():

warnings.simplefilter('ignore', category=DeprecationWarning)

import audioop

return audioop.alaw2lin(data, 2)

def _ulaw2lin(self, data):

with warnings.catch_warnings():

warnings.simplefilter('ignore', category=DeprecationWarning)

import audioop

return audioop.ulaw2lin(data, 2)

def _adpcm2lin(self, data):

with warnings.catch_warnings():

warnings.simplefilter('ignore', category=DeprecationWarning)

import audioop

if not hasattr(self, '_adpcmstate'):

# first time

self._adpcmstate = None

data, self._adpcmstate = audioop.adpcm2lin(data, 2, self._adpcmstate)

return data

def _sowt2lin(self, data):

with warnings.catch_warnings():

warnings.simplefilter('ignore', category=DeprecationWarning)

import audioop

return audioop.byteswap(data, 2)

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))

if self._sampwidth <= 0:

raise Error('bad sample width')

if self._nchannels <= 0:

raise Error('bad # of channels')

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

warnings.warn('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 != b'NONE':

if self._comptype == b'G722':

self._convert = self._adpcm2lin

elif self._comptype in (b'ulaw', b'ULAW'):

self._convert = self._ulaw2lin

elif self._comptype in (b'alaw', b'ALAW'):

self._convert = self._alaw2lin

elif self._comptype in (b'sowt', b'SOWT'):

self._convert = self._sowt2lin

else:

raise Error('unsupported compression type')

self._sampwidth = 2

else:

self._comptype = b'NONE'

self._compname = b'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:

w = ('Warning: MARK chunk contains only %s marker%s instead of %s' %

(len(self._markers), '' if len(self._markers) == 1 else 's',

nmarkers))

warnings.warn(w)

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

_file = None # Set here since __del__ checks it

def __init__(self, f):

if isinstance(f, str):

file_object = builtins.open(f, 'wb')

try:

self.initfp(file_object)

except:

file_object.close()

raise

# treat .aiff file extensions as non-compressed audio

if f.endswith('.aiff'):

self._aifc = 0

else:

# assume it is an open file object already

self.initfp(f)

def initfp(self, file):

self._file = file

self._version = _AIFC_version

self._comptype = b'NONE'

self._compname = b'not compressed'

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):

self.close()

def __enter__(self):

return self

def __exit__(self, *args):

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 (b'NONE', b'ulaw', b'ULAW',

b'alaw', b'ALAW', b'G722', b'sowt', b'SOWT'):

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, params):

nchannels, sampwidth, framerate, nframes, comptype, compname = params

if self._nframeswritten:

raise Error('cannot change parameters after starting to write')

if comptype not in (b'NONE', b'ulaw', b'ULAW',

b'alaw', b'ALAW', b'G722', b'sowt', b'SOWT'):

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 _aifc_params(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 not isinstance(name, bytes):

raise Error('marker name must be bytes')

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 {0!r} does not exist'.format(id))

def getmarkers(self):

if len(self._markers) == 0:

return None

return self._markers

def tell(self):

return self._nframeswritten

def writeframesraw(self, data):

if not isinstance(data, (bytes, bytearray)):

data = memoryview(data).cast('B')

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):

if self._file is None:

return

try:

self._ensure_header_written(0)

if self._datawritten & 1:

# quick pad to even size

self._file.write(b'\x00')

self._datawritten = self._datawritten + 1

self._writemarkers()

if self._nframeswritten != self._nframes or \

self._datalength != self._datawritten or \

self._marklength:

self._patchheader()

finally:

# Prevent ref cycles

self._convert = None

f = self._file

self._file = None

f.close()

#

# Internal methods.

#

def _lin2alaw(self, data):

with warnings.catch_warnings():

warnings.simplefilter('ignore', category=DeprecationWarning)

import audioop

return audioop.lin2alaw(data, 2)

def _lin2ulaw(self, data):

with warnings.catch_warnings():

warnings.simplefilter('ignore', category=DeprecationWarning)

import audioop

return audioop.lin2ulaw(data, 2)

def _lin2adpcm(self, data):

with warnings.catch_warnings():

warnings.simplefilter('ignore', category=DeprecationWarning)

import audioop

if not hasattr(self, '_adpcmstate'):

self._adpcmstate = None

data, self._adpcmstate = audioop.lin2adpcm(data, 2, self._adpcmstate)

return data

def _lin2sowt(self, data):

with warnings.catch_warnings():

warnings.simplefilter('ignore', category=DeprecationWarning)

import audioop

return audioop.byteswap(data, 2)

def _ensure_header_written(self, datasize):

if not self._nframeswritten:

if self._comptype in (b'ULAW', b'ulaw',

b'ALAW', b'alaw', b'G722',

b'sowt', b'SOWT'):

if not self._sampwidth:

self._sampwidth = 2

if self._sampwidth != 2:

raise Error('sample width must be 2 when compressing '

'with ulaw/ULAW, alaw/ALAW, sowt/SOWT '

'or 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 == b'G722':

self._convert = self._lin2adpcm

elif self._comptype in (b'ulaw', b'ULAW'):

self._convert = self._lin2ulaw

elif self._comptype in (b'alaw', b'ALAW'):

self._convert = self._lin2alaw

elif self._comptype in (b'sowt', b'SOWT'):

self._convert = self._lin2sowt

def _write_header(self, initlength):

if self._aifc and self._comptype != b'NONE':

self._init_compression()

self._file.write(b'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 (b'ulaw', b'ULAW', b'alaw', b'ALAW'):

self._datalength = self._datalength // 2

if self._datalength & 1:

self._datalength = self._datalength + 1

elif self._comptype == b'G722':

self._datalength = (self._datalength + 3) // 4

if self._datalength & 1:

self._datalength = self._datalength + 1

try:

self._form_length_pos = self._file.tell()

except (AttributeError, OSError):

self._form_length_pos = None

commlength = self._write_form_length(self._datalength)

if self._aifc:

self._file.write(b'AIFC')

self._file.write(b'FVER')

_write_ulong(self._file, 4)

_write_ulong(self._file, self._version)

else:

self._file.write(b'AIFF')

self._file.write(b'COMM')

_write_ulong(self._file, commlength)

_write_short(self._file, self._nchannels)

if self._form_length_pos is not None:

self._nframes_pos = self._file.tell()

_write_ulong(self._file, self._nframes)

if self._comptype in (b'ULAW', b'ulaw', b'ALAW', b'alaw', b'G722'):

_write_short(self._file, 8)

else:

_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(b'SSND')

if self._form_length_pos is not None:

self._ssnd_length_pos = self._file.tell()

_write_ulong(self._file, self._datalength + 8)

_write_ulong(self._file, 0)

_write_ulong(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_ulong(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(b'\x00')

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_ulong(self._file, self._nframeswritten)

self._file.seek(self._ssnd_length_pos, 0)

_write_ulong(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(b'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_ulong(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_ulong(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 __name__ == '__main__':

import sys

if not sys.argv[1:]:

sys.argv.append('/usr/demos/data/audio/bach.aiff')

fn = sys.argv[1]

with open(fn, 'r') as f:

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)

with open(gn, 'w') as g:

g.setparams(f.getparams())

while 1:

data = f.readframes(1024)

if not data:

break

g.writeframes(data)

print("Done.")