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cpython/Lib/aifc.py
Sjoerd Mullender 4150ede53c Fixed dealing with faulty COMM chunks.
1993-08-26 14:12:07 +00:00

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# 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)
# if 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')
# or
# f = aifc.openfp(filep, 'r')
# where file is the name of a file and filep is 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.
#
# Writing AIFF files:
# f = aifc.open(file, 'w')
# or
# f = aifc.openfp(filep, 'w')
# where file is the name of a file and filep is 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(nchannels, sampwidth, framerate, nframes, comptype, compname)
# -- 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 the 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.
#
# 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 builtin
import AL
try:
import CL
except ImportError:
pass
Error = 'aifc.Error'
_AIFC_version = 0xA2805140 # Version 1 of AIFF-C
_skiplist = 'COMT', 'INST', 'MIDI', 'AESD', \
'APPL', 'NAME', 'AUTH', '(c) ', 'ANNO'
_nchannelslist = [(1, AL.MONO), (2, AL.STEREO)]
_sampwidthlist = [(8, AL.SAMPLE_8), (16, AL.SAMPLE_16), (24, AL.SAMPLE_24)]
_frameratelist = [(48000, AL.RATE_48000), \
(44100, AL.RATE_44100), \
(32000, AL.RATE_32000), \
(22050, AL.RATE_22050), \
(16000, AL.RATE_16000), \
(11025, AL.RATE_11025), \
( 8000, AL.RATE_8000)]
def _convert1(value, list):
for t in list:
if value == t[0]:
return t[1]
raise Error, 'unknown parameter value'
def _convert2(value, list):
for t in list:
if value == t[1]:
return t[0]
raise Error, 'unknown parameter value'
def _read_long(file):
x = 0L
for i in range(4):
byte = file.read(1)
if byte == '':
raise EOFError
x = x*256 + ord(byte)
if x >= 0x80000000L:
x = x - 0x100000000L
return int(x)
def _read_ulong(file):
x = 0L
for i in range(4):
byte = file.read(1)
if byte == '':
raise EOFError
x = x*256 + ord(byte)
return x
def _read_short(file):
x = 0
for i in range(2):
byte = file.read(1)
if byte == '':
raise EOFError
x = x*256 + ord(byte)
if x >= 0x8000:
x = x - 0x10000
return x
def _read_string(file):
length = ord(file.read(1))
data = file.read(length)
if length & 1 == 0:
dummy = file.read(1)
return data
_HUGE_VAL = 1.79769313486231e+308 # See <limits.h>
def _read_float(f): # 10 bytes
import math
expon = _read_short(f) # 2 bytes
sign = 1
if expon < 0:
sign = -1
expon = expon + 0x8000
himant = _read_ulong(f) # 4 bytes
lomant = _read_ulong(f) # 4 bytes
if expon == himant == lomant == 0:
f = 0.0
elif expon == 0x7FFF:
f = _HUGE_VAL
else:
expon = expon - 16383
f = (himant * 0x100000000L + lomant) * pow(2.0, expon - 63)
return sign * f
def _write_short(f, x):
d, m = divmod(x, 256)
f.write(chr(d))
f.write(chr(m))
def _write_long(f, x):
if x < 0:
x = x + 0x100000000L
data = []
for i in range(4):
d, m = divmod(x, 256)
data.insert(0, m)
x = d
for i in range(4):
f.write(chr(int(data[i])))
def _write_string(f, s):
f.write(chr(len(s)))
f.write(s)
if len(s) & 1 == 0:
f.write(chr(0))
def _write_float(f, x):
import math
if x < 0:
sign = 0x8000
x = x * -1
else:
sign = 0
if x == 0:
expon = 0
himant = 0
lomant = 0
else:
fmant, expon = math.frexp(x)
if expon > 16384 or fmant >= 1: # Infinity or NaN
expon = sign|0x7FFF
himant = 0
lomant = 0
else: # Finite
expon = expon + 16382
if expon < 0: # denormalized
fmant = math.ldexp(fmant, expon)
expon = 0
expon = expon | sign
fmant = math.ldexp(fmant, 32)
fsmant = math.floor(fmant)
himant = long(fsmant)
fmant = math.ldexp(fmant - fsmant, 32)
fsmant = math.floor(fmant)
lomant = long(fsmant)
_write_short(f, expon)
_write_long(f, himant)
_write_long(f, lomant)
class Chunk:
def init(self, file):
self.file = file
self.chunkname = self.file.read(4)
if len(self.chunkname) < 4:
raise EOFError
self.chunksize = _read_long(self.file)
self.size_read = 0
self.offset = self.file.tell()
return self
def rewind(self):
self.file.seek(self.offset, 0)
self.size_read = 0
def setpos(self, pos):
if pos < 0 or pos > self.chunksize:
raise RuntimeError
self.file.seek(self.offset + pos, 0)
self.size_read = pos
def read(self, length):
if self.size_read >= self.chunksize:
return ''
if length > self.chunksize - self.size_read:
length = self.chunksize - self.size_read
data = self.file.read(length)
self.size_read = self.size_read + len(data)
return data
def skip(self):
try:
self.file.seek(self.chunksize - self.size_read, 1)
except RuntimeError:
while self.size_read < self.chunksize:
dummy = self.read(8192)
if not dummy:
raise EOFError
if self.chunksize & 1:
dummy = self.read(1)
class Aifc_read:
# Variables used in this class:
#
# These variables are available to the user though appropriate
# methods of this class:
# _file -- the open file with methods read(), close(), and seek()
# set through the init() ir initfp() 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
# tell() 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._file = file
self._version = 0
self._decomp = None
self._markers = []
self._soundpos = 0
form = self._file.read(4)
if form != 'FORM':
raise Error, 'file does not start with FORM id'
formlength = _read_long(self._file)
if formlength <= 0:
raise Error, 'invalid FORM chunk data size'
formdata = self._file.read(4)
formlength = formlength - 4
if formdata == 'AIFF':
self._aifc = 0
elif formdata == 'AIFC':
self._aifc = 1
else:
raise Error, 'not an AIFF or AIFF-C file'
self._comm_chunk_read = 0
while formlength > 0:
self._ssnd_seek_needed = 1
#DEBUG: SGI's soundfiler has a bug. There should
# be no need to check for EOF here.
try:
chunk = Chunk().init(self._file)
except EOFError:
if formlength == 8:
print 'Warning: FORM chunk size too large'
formlength = 0
break
raise EOFError # different error, raise exception
if chunk.chunkname == 'COMM':
self._read_comm_chunk(chunk)
self._comm_chunk_read = 1
elif chunk.chunkname == 'SSND':
self._ssnd_chunk = chunk
dummy = chunk.read(8)
self._ssnd_seek_needed = 0
elif chunk.chunkname == 'FVER':
self._version = _read_long(chunk)
elif chunk.chunkname == 'MARK':
self._readmark(chunk)
elif chunk.chunkname in _skiplist:
pass
else:
raise Error, 'unrecognized chunk type '+chunk.chunkname
formlength = formlength - 8 - chunk.chunksize
if chunk.chunksize & 1:
formlength = formlength - 1
if formlength > 0:
chunk.skip()
if not self._comm_chunk_read or not self._ssnd_chunk:
raise Error, 'COMM chunk and/or SSND chunk missing'
if self._aifc and self._decomp:
params = [CL.ORIGINAL_FORMAT, 0, \
CL.BITS_PER_COMPONENT, 0, \
CL.FRAME_RATE, self._framerate]
if self._nchannels == AL.MONO:
params[1] = CL.MONO
else:
params[1] = CL.STEREO_INTERLEAVED
if self._sampwidth == AL.SAMPLE_8:
params[3] = 8
elif self._sampwidth == AL.SAMPLE_16:
params[3] = 16
else:
params[3] = 24
self._decomp.SetParams(params)
return self
def init(self, filename):
return self.initfp(builtin.open(filename, 'r'))
#
# 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.close()
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._nchannels, self._sampwidth, self._framerate, \
self._nframes, self._comptype, self._compname
def getmarkers(self):
if len(self._markers) == 0:
return None
return self._markers
def getmark(self, id):
for marker in self._markers:
if id == marker[0]:
return marker
raise Error, 'marker ' + `id` + ' does not exist'
def setpos(self, pos):
if pos < 0 or pos > self._nframes:
raise Error, 'position not in range'
self._soundpos = pos
self._ssnd_seek_needed = 1
def readframes(self, nframes):
if self._ssnd_seek_needed:
self._ssnd_chunk.rewind()
dummy = self._ssnd_chunk.read(8)
pos = self._soundpos * self._framesize
if pos:
self._ssnd_chunk.setpos(pos + 8)
self._ssnd_seek_needed = 0
if nframes == 0:
return ''
data = self._ssnd_chunk.read(nframes * self._framesize)
if self._decomp and data:
dummy = self._decomp.SetParam(CL.FRAME_BUFFER_SIZE, \
len(data) * 2)
data = self._decomp.Decompress(len(data) / self._nchannels, data)
self._soundpos = self._soundpos + len(data) / (self._nchannels * self._sampwidth)
return data
#
# Internal methods.
#
def _read_comm_chunk(self, chunk):
nchannels = _read_short(chunk)
self._nchannels = _convert1(nchannels, _nchannelslist)
self._nframes = _read_long(chunk)
sampwidth = _read_short(chunk)
self._sampwidth = _convert1(sampwidth, _sampwidthlist)
framerate = _read_float(chunk)
self._framerate = _convert1(framerate, _frameratelist)
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':
try:
import cl, CL
except ImportError:
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)
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)
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() or initfp() 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, filename):
self = self.initfp(builtin.open(filename, 'w'))
if filename[-5:] == '.aiff':
self._aifc = 0
else:
self._aifc = 1
return self
def initfp(self, file):
self._file = file
self._version = _AIFC_version
self._comptype = 'NONE'
self._compname = 'not compressed'
self._comp = 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
return self
#
# 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'
dummy = _convert2(nchannels, _nchannelslist)
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'
dummy = _convert2(sampwidth, _sampwidthlist)
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'
dummy = _convert2(framerate, _frameratelist)
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'):
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'):
raise Error, 'unsupported compression type'
dummy = _convert2(nchannels, _nchannelslist)
dummy = _convert2(sampwidth, _sampwidthlist)
dummy = _convert2(framerate, _frameratelist)
self._nchannels = nchannels
self._sampwidth = sampwidth
self._framerate = framerate
self._nframes = nframes
self._comptype = comptype
self._compname = 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 writeframesraw(self, data):
self._ensure_header_written(len(data))
nframes = len(data) / (self._sampwidth * self._nchannels)
if self._comp:
dummy = self._comp.SetParam(CL.FRAME_BUFFER_SIZE, \
len(data))
dummy = self._comp.SetParam(CL.COMPRESSED_BUFFER_SIZE,\
len(data))
data = self._comp.Compress(nframes, 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.close()
self._file = None
#
# Internal methods.
#
def _ensure_header_written(self, datasize):
if not self._nframeswritten:
if self._comptype in ('ULAW', 'ALAW'):
if not self._sampwidth:
self._sampwidth = AL.SAMPLE_16
if self._sampwidth != AL.SAMPLE_16:
raise Error, 'sample width must be 2 when compressing with ULAW or ALAW'
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 _write_header(self, initlength):
if self._aifc and self._comptype != 'NONE':
try:
import cl, CL
except ImportError:
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, 0, \
CL.FRAME_RATE, self._framerate, \
CL.FRAME_BUFFER_SIZE, 100, \
CL.COMPRESSED_BUFFER_SIZE, 100]
if self._nchannels == AL.MONO:
params[1] = CL.MONO
else:
params[1] = CL.STEREO_INTERLEAVED
if self._sampwidth == AL.SAMPLE_8:
params[3] = 8
elif self._sampwidth == AL.SAMPLE_16:
params[3] = 16
else:
params[3] = 24
self._comp.SetParams(params)
# the compressor produces a header which we ignore
dummy = self._comp.Compress(0, '')
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 and self._comptype in ('ULAW', 'ALAW'):
self._datalength = self._datalength / 2
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, _convert2(self._nchannels, _nchannelslist))
self._nframes_pos = self._file.tell()
_write_long(self._file, self._nframes)
_write_short(self._file, _convert2(self._sampwidth, _sampwidthlist))
_write_float(self._file, _convert2(self._framerate, _frameratelist))
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(filename, mode):
if mode == 'r':
return Aifc_read().init(filename)
elif mode == 'w':
return Aifc_write().init(filename)
else:
raise Error, 'mode must be \'r\' or \'w\''
def openfp(filep, mode):
if mode == 'r':
return Aifc_read().initfp(filep)
elif mode == 'w':
return Aifc_write().initfp(filep)
else:
raise Error, 'mode must be \'r\' or \'w\''
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