ref: ce062debb1edaa27548deea0f151a9d4c95414a7
dir: /sys/lib/python/aifc.py/
"""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, (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 %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."