"""Stuff to parse Sun and NeXT audio files.

An audio file consists of a header followed by the data. The structure

of the header is as follows.

+---------------+

| magic word |

+---------------+

| header size |

+---------------+

| data size |

+---------------+

| encoding |

+---------------+

| sample rate |

+---------------+

| # of channels |

+---------------+

| info |

| |

+---------------+

The magic word consists of the 4 characters '.snd'. Apart from the

info field, all header fields are 4 bytes in size. They are all

32-bit unsigned integers encoded in big-endian byte order.

The header size really gives the start of the data.

The data size is the physical size of the data. From the other

parameters the number of frames can be calculated.

The encoding gives the way in which audio samples are encoded.

Possible values are listed below.

The info field currently consists of an ASCII string giving a

human-readable description of the audio file. The info field is

padded with NUL bytes to the header size.

Usage.

Reading audio files:

f = sunau.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' or 'ULAW')

getcompname() -- returns human-readable version of

compression type ('not compressed' matches 'NONE')

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 audio files:

f = sunau.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(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 warnings

_sunau_params = namedtuple('_sunau_params',

'nchannels sampwidth framerate nframes comptype compname')

# from <multimedia/audio_filehdr.h>

AUDIO_FILE_MAGIC = 0x2e736e64

AUDIO_FILE_ENCODING_MULAW_8 = 1

AUDIO_FILE_ENCODING_LINEAR_8 = 2

AUDIO_FILE_ENCODING_LINEAR_16 = 3

AUDIO_FILE_ENCODING_LINEAR_24 = 4

AUDIO_FILE_ENCODING_LINEAR_32 = 5

AUDIO_FILE_ENCODING_FLOAT = 6

AUDIO_FILE_ENCODING_DOUBLE = 7

AUDIO_FILE_ENCODING_ADPCM_G721 = 23

AUDIO_FILE_ENCODING_ADPCM_G722 = 24

AUDIO_FILE_ENCODING_ADPCM_G723_3 = 25

AUDIO_FILE_ENCODING_ADPCM_G723_5 = 26

AUDIO_FILE_ENCODING_ALAW_8 = 27

# from <multimedia/audio_hdr.h>

AUDIO_UNKNOWN_SIZE = 0xFFFFFFFF # ((unsigned)(~0))

_simple_encodings = [AUDIO_FILE_ENCODING_MULAW_8,

AUDIO_FILE_ENCODING_LINEAR_8,

AUDIO_FILE_ENCODING_LINEAR_16,

AUDIO_FILE_ENCODING_LINEAR_24,

AUDIO_FILE_ENCODING_LINEAR_32,

AUDIO_FILE_ENCODING_ALAW_8]

class Error(Exception):

pass

def _read_u32(file):

x = 0

for i in range(4):

byte = file.read(1)

if not byte:

raise EOFError

x = x*256 + ord(byte)

return x

def _write_u32(file, x):

data = []

for i in range(4):

d, m = divmod(x, 256)

data.insert(0, int(m))

x = d

file.write(bytes(data))

class Au_read:

def __init__(self, f):

if type(f) == type(''):

import builtins

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

self._opened = True

else:

self._opened = False

self.initfp(f)

def __del__(self):

if self._file:

self.close()

def __enter__(self):

return self

def __exit__(self, *args):

self.close()

def initfp(self, file):

self._file = file

self._soundpos = 0

magic = int(_read_u32(file))

if magic != AUDIO_FILE_MAGIC:

raise Error('bad magic number')

self._hdr_size = int(_read_u32(file))

if self._hdr_size < 24:

raise Error('header size too small')

if self._hdr_size > 100:

raise Error('header size ridiculously large')

self._data_size = _read_u32(file)

if self._data_size != AUDIO_UNKNOWN_SIZE:

self._data_size = int(self._data_size)

self._encoding = int(_read_u32(file))

if self._encoding not in _simple_encodings:

raise Error('encoding not (yet) supported')

if self._encoding in (AUDIO_FILE_ENCODING_MULAW_8,

AUDIO_FILE_ENCODING_ALAW_8):

self._sampwidth = 2

self._framesize = 1

elif self._encoding == AUDIO_FILE_ENCODING_LINEAR_8:

self._framesize = self._sampwidth = 1

elif self._encoding == AUDIO_FILE_ENCODING_LINEAR_16:

self._framesize = self._sampwidth = 2

elif self._encoding == AUDIO_FILE_ENCODING_LINEAR_24:

self._framesize = self._sampwidth = 3

elif self._encoding == AUDIO_FILE_ENCODING_LINEAR_32:

self._framesize = self._sampwidth = 4

else:

raise Error('unknown encoding')

self._framerate = int(_read_u32(file))

self._nchannels = int(_read_u32(file))

if not self._nchannels:

raise Error('bad # of channels')

self._framesize = self._framesize * self._nchannels

if self._hdr_size > 24:

self._info = file.read(self._hdr_size - 24)

self._info, _, _ = self._info.partition(b'\0')

else:

self._info = b''

try:

self._data_pos = file.tell()

except (AttributeError, OSError):

self._data_pos = None

def getfp(self):

return self._file

def getnchannels(self):

return self._nchannels

def getsampwidth(self):

return self._sampwidth

def getframerate(self):

return self._framerate

def getnframes(self):

if self._data_size == AUDIO_UNKNOWN_SIZE:

return AUDIO_UNKNOWN_SIZE

if self._encoding in _simple_encodings:

return self._data_size // self._framesize

return 0 # XXX--must do some arithmetic here

def getcomptype(self):

if self._encoding == AUDIO_FILE_ENCODING_MULAW_8:

return 'ULAW'

elif self._encoding == AUDIO_FILE_ENCODING_ALAW_8:

return 'ALAW'

else:

return 'NONE'

def getcompname(self):

if self._encoding == AUDIO_FILE_ENCODING_MULAW_8:

return 'CCITT G.711 u-law'

elif self._encoding == AUDIO_FILE_ENCODING_ALAW_8:

return 'CCITT G.711 A-law'

else:

return 'not compressed'

def getparams(self):

return _sunau_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 readframes(self, nframes):

if self._encoding in _simple_encodings:

if nframes == AUDIO_UNKNOWN_SIZE:

data = self._file.read()

else:

data = self._file.read(nframes * self._framesize)

self._soundpos += len(data) // self._framesize

if self._encoding == AUDIO_FILE_ENCODING_MULAW_8:

import audioop

data = audioop.ulaw2lin(data, self._sampwidth)

return data

return None # XXX--not implemented yet

def rewind(self):

if self._data_pos is None:

raise OSError('cannot seek')

self._file.seek(self._data_pos)

self._soundpos = 0

def tell(self):

return self._soundpos

def setpos(self, pos):

if pos < 0 or pos > self.getnframes():

raise Error('position not in range')

if self._data_pos is None:

raise OSError('cannot seek')

self._file.seek(self._data_pos + pos * self._framesize)

self._soundpos = pos

def close(self):

file = self._file

if file:

self._file = None

if self._opened:

file.close()

class Au_write:

def __init__(self, f):

if type(f) == type(''):

import builtins

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

self._opened = True

else:

self._opened = False

self.initfp(f)

def __del__(self):

if self._file:

self.close()

self._file = None

def __enter__(self):

return self

def __exit__(self, *args):

self.close()

def initfp(self, file):

self._file = file

self._framerate = 0

self._nchannels = 0

self._sampwidth = 0

self._framesize = 0

self._nframes = AUDIO_UNKNOWN_SIZE

self._nframeswritten = 0

self._datawritten = 0

self._datalength = 0

self._info = b''

self._comptype = 'ULAW' # default is U-law

def setnchannels(self, nchannels):

if self._nframeswritten:

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

if nchannels not in (1, 2, 4):

raise Error('only 1, 2, or 4 channels supported')

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 not in (1, 2, 3, 4):

raise Error('bad sample width')

self._sampwidth = sampwidth

def getsampwidth(self):

if not self._framerate:

raise Error('sample width not specified')

return self._sampwidth

def setframerate(self, framerate):

if self._nframeswritten:

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

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')

if nframes < 0:

raise Error('# of frames cannot be negative')

self._nframes = nframes

def getnframes(self):

return self._nframeswritten

def setcomptype(self, type, name):

if type in ('NONE', 'ULAW'):

self._comptype = type

else:

raise Error('unknown compression type')

def getcomptype(self):

return self._comptype

def getcompname(self):

if self._comptype == 'ULAW':

return 'CCITT G.711 u-law'

elif self._comptype == 'ALAW':

return 'CCITT G.711 A-law'

else:

return 'not compressed'

def setparams(self, params):

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

self.setnchannels(nchannels)

self.setsampwidth(sampwidth)

self.setframerate(framerate)

self.setnframes(nframes)

self.setcomptype(comptype, compname)

def getparams(self):

return _sunau_params(self.getnchannels(), self.getsampwidth(),

self.getframerate(), self.getnframes(),

self.getcomptype(), self.getcompname())

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()

if self._comptype == 'ULAW':

import audioop

data = audioop.lin2ulaw(data, self._sampwidth)

nframes = len(data) // self._framesize

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:

try:

self._ensure_header_written()

if self._nframeswritten != self._nframes or \

self._datalength != self._datawritten:

self._patchheader()

self._file.flush()

finally:

file = self._file

self._file = None

if self._opened:

file.close()

#

# private methods

#

def _ensure_header_written(self):

if not self._nframeswritten:

if not self._nchannels:

raise Error('# of channels not specified')

if not self._sampwidth:

raise Error('sample width not specified')

if not self._framerate:

raise Error('frame rate not specified')

self._write_header()

def _write_header(self):

if self._comptype == 'NONE':

if self._sampwidth == 1:

encoding = AUDIO_FILE_ENCODING_LINEAR_8

self._framesize = 1

elif self._sampwidth == 2:

encoding = AUDIO_FILE_ENCODING_LINEAR_16

self._framesize = 2

elif self._sampwidth == 3:

encoding = AUDIO_FILE_ENCODING_LINEAR_24

self._framesize = 3

elif self._sampwidth == 4:

encoding = AUDIO_FILE_ENCODING_LINEAR_32

self._framesize = 4

else:

raise Error('internal error')

elif self._comptype == 'ULAW':

encoding = AUDIO_FILE_ENCODING_MULAW_8

self._framesize = 1

else:

raise Error('internal error')

self._framesize = self._framesize * self._nchannels

_write_u32(self._file, AUDIO_FILE_MAGIC)

header_size = 25 + len(self._info)

header_size = (header_size + 7) & ~7

_write_u32(self._file, header_size)

if self._nframes == AUDIO_UNKNOWN_SIZE:

length = AUDIO_UNKNOWN_SIZE

else:

length = self._nframes * self._framesize

try:

self._form_length_pos = self._file.tell()

except (AttributeError, OSError):

self._form_length_pos = None

_write_u32(self._file, length)

self._datalength = length

_write_u32(self._file, encoding)

_write_u32(self._file, self._framerate)

_write_u32(self._file, self._nchannels)

self._file.write(self._info)

self._file.write(b'\0'*(header_size - len(self._info) - 24))

def _patchheader(self):

if self._form_length_pos is None:

raise OSError('cannot seek')

self._file.seek(self._form_length_pos)

_write_u32(self._file, self._datawritten)

self._datalength = self._datawritten

self._file.seek(0, 2)

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 Au_read(f)

elif mode in ('w', 'wb'):

return Au_write(f)

else:

raise Error("mode must be 'r', 'rb', 'w', or 'wb'")

def openfp(f, mode=None):

warnings.warn("sunau.openfp is deprecated since Python 3.7. "

"Use sunau.open instead.", DeprecationWarning, stacklevel=2)

return open(f, mode=mode)