cpython/Lib/wave.py

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# Stuff to parse WAVE files.
#
# Usage.
#
# Reading WAVE files:
# f = wave.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().
# When the setpos() and rewind() methods are 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 linear samples)
# getcompname() -- returns human-readable version of
# compression type ('not compressed' linear samples)
# getparams() -- returns a tuple consisting of all of the
# above in the above order
# getmarkers() -- returns None (for compatibility with the
# aifc module)
# getmark(id) -- raises an error since the mark does not
# exist (for compatibility with the aifc module)
# 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() and the position given to setpos()
# are compatible and have nothing to do with the actual postion in the
# file.
# The close() method is called automatically when the class instance
# is destroyed.
#
# Writing WAVE files:
# f = wave.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:
# 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
# tell() -- return current position in output file
# 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.
# The close() method is called automatically when the class instance
# is destroyed.
import __builtin__
Error = 'wave.Error'
WAVE_FORMAT_PCM = 0x0001
_array_fmts = None, 'b', 'h', None, 'l'
# Determine endian-ness
import struct
if struct.pack("h", 1) == "\000\001":
big_endian = 1
else:
big_endian = 0
from chunk import Chunk
class Wave_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
# _soundpos -- the position in the audio stream
# available through the tell() method, set through the
# setpos() method
#
# These variables are used internally only:
# _fmt_chunk_read -- 1 iff the FMT chunk has been read
# _data_seek_needed -- 1 iff positioned correctly in audio
# file for readframes()
# _data_chunk -- instantiation of a chunk class for the DATA chunk
# _framesize -- size of one frame in the file
def initfp(self, file):
self._convert = None
self._soundpos = 0
self._file = Chunk(file, bigendian = 0)
if self._file.getname() != 'RIFF':
raise Error, 'file does not start with RIFF id'
if self._file.read(4) != 'WAVE':
raise Error, 'not a WAVE file'
self._fmt_chunk_read = 0
self._data_chunk = None
while 1:
self._data_seek_needed = 1
try:
chunk = Chunk(self._file, bigendian = 0)
except EOFError:
break
chunkname = chunk.getname()
if chunkname == 'fmt ':
self._read_fmt_chunk(chunk)
self._fmt_chunk_read = 1
elif chunkname == 'data':
if not self._fmt_chunk_read:
raise Error, 'data chunk before fmt chunk'
self._data_chunk = chunk
self._nframes = chunk.chunksize / self._framesize
self._data_seek_needed = 0
break
chunk.skip()
if not self._fmt_chunk_read or not self._data_chunk:
raise Error, 'fmt chunk and/or data chunk missing'
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._data_seek_needed = 1
self._soundpos = 0
def close(self):
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 getparams(self):
return self.getnchannels(), self.getsampwidth(), \
self.getframerate(), self.getnframes(), \
self.getcomptype(), self.getcompname()
def getmarkers(self):
return None
def getmark(self, id):
raise Error, 'no marks'
def setpos(self, pos):
if pos < 0 or pos > self._nframes:
raise Error, 'position not in range'
self._soundpos = pos
self._data_seek_needed = 1
def readframes(self, nframes):
if self._data_seek_needed:
self._data_chunk.seek(0, 0)
pos = self._soundpos * self._framesize
if pos:
self._data_chunk.seek(pos, 0)
self._data_seek_needed = 0
if nframes == 0:
return ''
if self._sampwidth > 1 and big_endian:
# unfortunately the fromfile() method does not take
# something that only looks like a file object, so
# we have to reach into the innards of the chunk object
import array
chunk = self._data_chunk
data = array.array(_array_fmts[self._sampwidth])
nitems = nframes * self._nchannels
if nitems * self._sampwidth > chunk.chunksize - chunk.size_read:
nitems = (chunk.chunksize - chunk.size_read) / self._sampwidth
data.fromfile(chunk.file.file, nitems)
# "tell" data chunk how much was read
chunk.size_read = chunk.size_read + nitems * self._sampwidth
# do the same for the outermost chunk
chunk = chunk.file
chunk.size_read = chunk.size_read + nitems * self._sampwidth
data.byteswap()
data = data.tostring()
else:
data = self._data_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 _read_fmt_chunk(self, chunk):
wFormatTag, self._nchannels, self._framerate, dwAvgBytesPerSec, wBlockAlign = struct.unpack('<hhllh', chunk.read(14))
if wFormatTag == WAVE_FORMAT_PCM:
sampwidth = struct.unpack('<h', chunk.read(2))[0]
self._sampwidth = (sampwidth + 7) / 8
else:
raise Error, 'unknown format: ' + `wFormatTag`
self._framesize = self._nchannels * self._sampwidth
self._comptype = 'NONE'
self._compname = 'not compressed'
class Wave_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
#
# These variables are used internally only:
# _datalength -- the size of the audio samples written to the header
# _nframeswritten -- the number of frames actually written
# _datawritten -- the size of the audio samples actually written
def __init__(self, f):
if type(f) == type(''):
f = __builtin__.open(f, 'wb')
self.initfp(f)
def initfp(self, file):
self._file = file
self._convert = None
self._nchannels = 0
self._sampwidth = 0
self._framerate = 0
self._nframes = 0
self._nframeswritten = 0
self._datawritten = 0
self._datalength = 0
def __del__(self):
if self._file:
self.close()
#
# User visible methods.
#
def setnchannels(self, nchannels):
if self._datawritten:
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._datawritten:
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._datawritten:
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._datawritten:
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._datawritten:
raise Error, 'cannot change parameters after starting to write'
if comptype not in ('NONE',):
raise Error, 'unsupported compression type'
self._comptype = comptype
self._compname = compname
def getcomptype(self):
return self._comptype
def getcompname(self):
return self._compname
def setparams(self, (nchannels, sampwidth, framerate, nframes, comptype, compname)):
if self._datawritten:
raise Error, 'cannot change parameters after starting to write'
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):
raise Error, 'setmark() not supported'
def getmark(self, id):
raise Error, 'no marks'
def getmarkers(self):
return None
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)
if self._sampwidth > 1 and big_endian:
import array
data = array.array(_array_fmts[self._sampwidth], data)
data.byteswap()
data.tofile(self._file)
self._datawritten = self._datawritten + len(data) * self._sampwidth
else:
self._file.write(data)
self._datawritten = self._datawritten + len(data)
self._nframeswritten = self._nframeswritten + nframes
def writeframes(self, data):
self.writeframesraw(data)
if self._datalength != self._datawritten:
self._patchheader()
def close(self):
self._ensure_header_written(0)
if self._datalength != self._datawritten:
self._patchheader()
self._file.flush()
self._file = None
#
# Internal methods.
#
def _ensure_header_written(self, datasize):
if not self._datawritten:
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):
self._file.write('RIFF')
if not self._nframes:
self._nframes = initlength / (self._nchannels * self._sampwidth)
self._datalength = self._nframes * self._nchannels * self._sampwidth
self._form_length_pos = self._file.tell()
self._file.write(struct.pack('<lsslhhllhhs',
36 + self._datalength, 'WAVE', 'fmt ', 16,
WAVE_FORMAT_PCM, self._nchannels, self._framerate,
self._nchannels * self._framerate * self._sampwidth,
self._nchannels * self._sampwidth,
self._sampwidth * 8, 'data'))
self._data_length_pos = self._file.tell()
self._file.write(struct.pack('<l', self._datalength))
def _patchheader(self):
if self._datawritten == self._datalength:
return
curpos = self._file.tell()
self._file.seek(self._form_length_pos, 0)
self._file.write(struct.pack('<l', 36 + self._datawritten))
self._file.seek(self._data_length_pos, 0)
self._file.write(struct.pack('<l', self._datawritten))
self._file.seek(curpos, 0)
self._datalength = self._datawritten
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 Wave_read(f)
elif mode in ('w', 'wb'):
return Wave_write(f)
else:
raise Error, "mode must be 'r', 'rb', 'w', or 'wb'"
openfp = open # B/W compatibility