"""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 namedtuple 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 position 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 patching 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.
The close() method is called automatically when the class instance
is destroyed.
"""
from collections import namedtuple
import builtins
import struct
import sys
__all__ = ["open", "Error", "Wave_read", "Wave_write"]
class Error(Exception):
pass
WAVE_FORMAT_PCM = 0x0001
_array_fmts = None, 'b', 'h', None, 'i'
_wave_params = namedtuple('_wave_params',
'nchannels sampwidth framerate nframes comptype compname')
def _byteswap(data, width):
swapped_data = bytearray(len(data))
for i in range(0, len(data), width):
for j in range(width):
swapped_data[i + width - 1 - j] = data[i + j]
return bytes(swapped_data)
class _Chunk:
def __init__(self, file, align=True, bigendian=True, inclheader=False):
self.closed = False
self.align = align # whether to align to word (2-byte) boundaries
if bigendian:
strflag = '>'
else:
strflag = '<'
self.file = file
self.chunkname = file.read(4)
if len(self.chunkname) < 4:
raise EOFError
try:
self.chunksize = struct.unpack_from(strflag+'L', file.read(4))[0]
except struct.error:
raise EOFError from None
if inclheader:
self.chunksize = self.chunksize - 8 # subtract header
self.size_read = 0
try:
self.offset = self.file.tell()
except (AttributeError, OSError):
self.seekable = False
else:
self.seekable = True
def getname(self):
"""Return the name (ID) of the current chunk."""
return self.chunkname
def close(self):
if not self.closed:
try:
self.skip()
finally:
self.closed = True
def seek(self, pos, whence=0):
"""Seek to specified position into the chunk.
Default position is 0 (start of chunk).
If the file is not seekable, this will result in an error.
"""
if self.closed:
raise ValueError("I/O operation on closed file")
if not self.seekable:
raise OSError("cannot seek")
if whence == 1:
pos = pos + self.size_read
elif whence == 2:
pos = pos + self.chunksize
if pos < 0 or pos > self.chunksize:
raise RuntimeError
self.file.seek(self.offset + pos, 0)
self.size_read = pos
def tell(self):
if self.closed:
raise ValueError("I/O operation on closed file")
return self.size_read
def read(self, size=-1):
"""Read at most size bytes from the chunk.
If size is omitted or negative, read until the end
of the chunk.
"""
if self.closed:
raise ValueError("I/O operation on closed file")
if self.size_read >= self.chunksize:
return b''
if size < 0:
size = self.chunksize - self.size_read
if size > self.chunksize - self.size_read:
size = self.chunksize - self.size_read
data = self.file.read(size)
self.size_read = self.size_read + len(data)
if self.size_read == self.chunksize and \
self.align and \
(self.chunksize & 1):
dummy = self.file.read(1)
self.size_read = self.size_read + len(dummy)
return data
def skip(self):
"""Skip the rest of the chunk.
If you are not interested in the contents of the chunk,
this method should be called so that the file points to
the start of the next chunk.
"""
if self.closed:
raise ValueError("I/O operation on closed file")
if self.seekable:
try:
n = self.chunksize - self.size_read
# maybe fix alignment
if self.align and (self.chunksize & 1):
n = n + 1
self.file.seek(n, 1)
self.size_read = self.size_read + n
return
except OSError:
pass
while self.size_read < self.chunksize:
n = min(8192, self.chunksize - self.size_read)
dummy = self.read(n)
if not dummy:
raise EOFError
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() != b'RIFF':
raise Error('file does not start with RIFF id')
if self._file.read(4) != b'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 == b'fmt ':
self._read_fmt_chunk(chunk)
self._fmt_chunk_read = 1
elif chunkname == b'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):
self._i_opened_the_file = None
if isinstance(f, str):
f = builtins.open(f, 'rb')
self._i_opened_the_file = f
# else, assume it is an open file object already
try:
self.initfp(f)
except:
if self._i_opened_the_file:
f.close()
raise
def __del__(self):
self.close()
def __enter__(self):
return self
def __exit__(self, *args):
self.close()
#
# 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
file = self._i_opened_the_file
if file:
self._i_opened_the_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 getparams(self):
return _wave_params(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 b''
data = self._data_chunk.read(nframes * self._framesize)
if self._sampwidth != 1 and sys.byteorder == 'big':
data = _byteswap(data, self._sampwidth)
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):
try:
wFormatTag, self._nchannels, self._framerate, dwAvgBytesPerSec, wBlockAlign = struct.unpack_from('<HHLLH', chunk.read(14))
except struct.error:
raise EOFError from None
if wFormatTag == WAVE_FORMAT_PCM:
try:
sampwidth = struct.unpack_from('<H', chunk.read(2))[0]
except struct.error:
raise EOFError from None
self._sampwidth = (sampwidth + 7) // 8
if not self._sampwidth:
raise Error('bad sample width')
else:
raise Error('unknown format: %r' % (wFormatTag,))
if not self._nchannels:
raise Error('bad # of channels')
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):
self._i_opened_the_file = None
if isinstance(f, str):
f = builtins.open(f, 'wb')
self._i_opened_the_file = f
try:
self.initfp(f)
except:
if self._i_opened_the_file:
f.close()
raise
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
self._headerwritten = False
def __del__(self):
self.close()
def __enter__(self):
return self
def __exit__(self, *args):
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 = int(round(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, params):
nchannels, sampwidth, framerate, nframes, comptype, compname = params
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 _wave_params(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):
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)
if self._sampwidth != 1 and sys.byteorder == 'big':
data = _byteswap(data, self._sampwidth)
self._file.write(data)
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):
try:
if self._file:
self._ensure_header_written(0)
if self._datalength != self._datawritten:
self._patchheader()
self._file.flush()
finally:
self._file = None
file = self._i_opened_the_file
if file:
self._i_opened_the_file = None
file.close()
#
# Internal methods.
#
def _ensure_header_written(self, datasize):
if not self._headerwritten:
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):
assert not self._headerwritten
self._file.write(b'RIFF')
if not self._nframes:
self._nframes = initlength // (self._nchannels * self._sampwidth)
self._datalength = self._nframes * self._nchannels * self._sampwidth
try:
self._form_length_pos = self._file.tell()
except (AttributeError, OSError):
self._form_length_pos = None
self._file.write(struct.pack('<L4s4sLHHLLHH4s',
36 + self._datalength, b'WAVE', b'fmt ', 16,
WAVE_FORMAT_PCM, self._nchannels, self._framerate,
self._nchannels * self._framerate * self._sampwidth,
self._nchannels * self._sampwidth,
self._sampwidth * 8, b'data'))
if self._form_length_pos is not None:
self._data_length_pos = self._file.tell()
self._file.write(struct.pack('<L', self._datalength))
self._headerwritten = True
def _patchheader(self):
assert self._headerwritten
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'")
