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Old engine for Continuous Time Bayesian Networks. Superseded by reCTBN. 🐍 https://github.com/madlabunimib/PyCTBN
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PyCTBN/venv/lib/python3.9/site-packages/scipy/io/wavfile.py

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"""
Module to read / write wav files using NumPy arrays
Functions
---------
`read`: Return the sample rate (in samples/sec) and data from a WAV file.
`write`: Write a NumPy array as a WAV file.
"""
import sys
import numpy
import struct
import warnings
from enum import IntEnum
__all__ = [
'WavFileWarning',
'read',
'write'
]
class WavFileWarning(UserWarning):
pass
class WAVE_FORMAT(IntEnum):
"""
WAVE form wFormatTag IDs
Complete list is in mmreg.h in Windows 10 SDK. ALAC and OPUS are the
newest additions, in v10.0.14393 2016-07
"""
UNKNOWN = 0x0000
PCM = 0x0001
ADPCM = 0x0002
IEEE_FLOAT = 0x0003
VSELP = 0x0004
IBM_CVSD = 0x0005
ALAW = 0x0006
MULAW = 0x0007
DTS = 0x0008
DRM = 0x0009
WMAVOICE9 = 0x000A
WMAVOICE10 = 0x000B
OKI_ADPCM = 0x0010
DVI_ADPCM = 0x0011
IMA_ADPCM = 0x0011 # Duplicate
MEDIASPACE_ADPCM = 0x0012
SIERRA_ADPCM = 0x0013
G723_ADPCM = 0x0014
DIGISTD = 0x0015
DIGIFIX = 0x0016
DIALOGIC_OKI_ADPCM = 0x0017
MEDIAVISION_ADPCM = 0x0018
CU_CODEC = 0x0019
HP_DYN_VOICE = 0x001A
YAMAHA_ADPCM = 0x0020
SONARC = 0x0021
DSPGROUP_TRUESPEECH = 0x0022
ECHOSC1 = 0x0023
AUDIOFILE_AF36 = 0x0024
APTX = 0x0025
AUDIOFILE_AF10 = 0x0026
PROSODY_1612 = 0x0027
LRC = 0x0028
DOLBY_AC2 = 0x0030
GSM610 = 0x0031
MSNAUDIO = 0x0032
ANTEX_ADPCME = 0x0033
CONTROL_RES_VQLPC = 0x0034
DIGIREAL = 0x0035
DIGIADPCM = 0x0036
CONTROL_RES_CR10 = 0x0037
NMS_VBXADPCM = 0x0038
CS_IMAADPCM = 0x0039
ECHOSC3 = 0x003A
ROCKWELL_ADPCM = 0x003B
ROCKWELL_DIGITALK = 0x003C
XEBEC = 0x003D
G721_ADPCM = 0x0040
G728_CELP = 0x0041
MSG723 = 0x0042
INTEL_G723_1 = 0x0043
INTEL_G729 = 0x0044
SHARP_G726 = 0x0045
MPEG = 0x0050
RT24 = 0x0052
PAC = 0x0053
MPEGLAYER3 = 0x0055
LUCENT_G723 = 0x0059
CIRRUS = 0x0060
ESPCM = 0x0061
VOXWARE = 0x0062
CANOPUS_ATRAC = 0x0063
G726_ADPCM = 0x0064
G722_ADPCM = 0x0065
DSAT = 0x0066
DSAT_DISPLAY = 0x0067
VOXWARE_BYTE_ALIGNED = 0x0069
VOXWARE_AC8 = 0x0070
VOXWARE_AC10 = 0x0071
VOXWARE_AC16 = 0x0072
VOXWARE_AC20 = 0x0073
VOXWARE_RT24 = 0x0074
VOXWARE_RT29 = 0x0075
VOXWARE_RT29HW = 0x0076
VOXWARE_VR12 = 0x0077
VOXWARE_VR18 = 0x0078
VOXWARE_TQ40 = 0x0079
VOXWARE_SC3 = 0x007A
VOXWARE_SC3_1 = 0x007B
SOFTSOUND = 0x0080
VOXWARE_TQ60 = 0x0081
MSRT24 = 0x0082
G729A = 0x0083
MVI_MVI2 = 0x0084
DF_G726 = 0x0085
DF_GSM610 = 0x0086
ISIAUDIO = 0x0088
ONLIVE = 0x0089
MULTITUDE_FT_SX20 = 0x008A
INFOCOM_ITS_G721_ADPCM = 0x008B
CONVEDIA_G729 = 0x008C
CONGRUENCY = 0x008D
SBC24 = 0x0091
DOLBY_AC3_SPDIF = 0x0092
MEDIASONIC_G723 = 0x0093
PROSODY_8KBPS = 0x0094
ZYXEL_ADPCM = 0x0097
PHILIPS_LPCBB = 0x0098
PACKED = 0x0099
MALDEN_PHONYTALK = 0x00A0
RACAL_RECORDER_GSM = 0x00A1
RACAL_RECORDER_G720_A = 0x00A2
RACAL_RECORDER_G723_1 = 0x00A3
RACAL_RECORDER_TETRA_ACELP = 0x00A4
NEC_AAC = 0x00B0
RAW_AAC1 = 0x00FF
RHETOREX_ADPCM = 0x0100
IRAT = 0x0101
VIVO_G723 = 0x0111
VIVO_SIREN = 0x0112
PHILIPS_CELP = 0x0120
PHILIPS_GRUNDIG = 0x0121
DIGITAL_G723 = 0x0123
SANYO_LD_ADPCM = 0x0125
SIPROLAB_ACEPLNET = 0x0130
SIPROLAB_ACELP4800 = 0x0131
SIPROLAB_ACELP8V3 = 0x0132
SIPROLAB_G729 = 0x0133
SIPROLAB_G729A = 0x0134
SIPROLAB_KELVIN = 0x0135
VOICEAGE_AMR = 0x0136
G726ADPCM = 0x0140
DICTAPHONE_CELP68 = 0x0141
DICTAPHONE_CELP54 = 0x0142
QUALCOMM_PUREVOICE = 0x0150
QUALCOMM_HALFRATE = 0x0151
TUBGSM = 0x0155
MSAUDIO1 = 0x0160
WMAUDIO2 = 0x0161
WMAUDIO3 = 0x0162
WMAUDIO_LOSSLESS = 0x0163
WMASPDIF = 0x0164
UNISYS_NAP_ADPCM = 0x0170
UNISYS_NAP_ULAW = 0x0171
UNISYS_NAP_ALAW = 0x0172
UNISYS_NAP_16K = 0x0173
SYCOM_ACM_SYC008 = 0x0174
SYCOM_ACM_SYC701_G726L = 0x0175
SYCOM_ACM_SYC701_CELP54 = 0x0176
SYCOM_ACM_SYC701_CELP68 = 0x0177
KNOWLEDGE_ADVENTURE_ADPCM = 0x0178
FRAUNHOFER_IIS_MPEG2_AAC = 0x0180
DTS_DS = 0x0190
CREATIVE_ADPCM = 0x0200
CREATIVE_FASTSPEECH8 = 0x0202
CREATIVE_FASTSPEECH10 = 0x0203
UHER_ADPCM = 0x0210
ULEAD_DV_AUDIO = 0x0215
ULEAD_DV_AUDIO_1 = 0x0216
QUARTERDECK = 0x0220
ILINK_VC = 0x0230
RAW_SPORT = 0x0240
ESST_AC3 = 0x0241
GENERIC_PASSTHRU = 0x0249
IPI_HSX = 0x0250
IPI_RPELP = 0x0251
CS2 = 0x0260
SONY_SCX = 0x0270
SONY_SCY = 0x0271
SONY_ATRAC3 = 0x0272
SONY_SPC = 0x0273
TELUM_AUDIO = 0x0280
TELUM_IA_AUDIO = 0x0281
NORCOM_VOICE_SYSTEMS_ADPCM = 0x0285
FM_TOWNS_SND = 0x0300
MICRONAS = 0x0350
MICRONAS_CELP833 = 0x0351
BTV_DIGITAL = 0x0400
INTEL_MUSIC_CODER = 0x0401
INDEO_AUDIO = 0x0402
QDESIGN_MUSIC = 0x0450
ON2_VP7_AUDIO = 0x0500
ON2_VP6_AUDIO = 0x0501
VME_VMPCM = 0x0680
TPC = 0x0681
LIGHTWAVE_LOSSLESS = 0x08AE
OLIGSM = 0x1000
OLIADPCM = 0x1001
OLICELP = 0x1002
OLISBC = 0x1003
OLIOPR = 0x1004
LH_CODEC = 0x1100
LH_CODEC_CELP = 0x1101
LH_CODEC_SBC8 = 0x1102
LH_CODEC_SBC12 = 0x1103
LH_CODEC_SBC16 = 0x1104
NORRIS = 0x1400
ISIAUDIO_2 = 0x1401
SOUNDSPACE_MUSICOMPRESS = 0x1500
MPEG_ADTS_AAC = 0x1600
MPEG_RAW_AAC = 0x1601
MPEG_LOAS = 0x1602
NOKIA_MPEG_ADTS_AAC = 0x1608
NOKIA_MPEG_RAW_AAC = 0x1609
VODAFONE_MPEG_ADTS_AAC = 0x160A
VODAFONE_MPEG_RAW_AAC = 0x160B
MPEG_HEAAC = 0x1610
VOXWARE_RT24_SPEECH = 0x181C
SONICFOUNDRY_LOSSLESS = 0x1971
INNINGS_TELECOM_ADPCM = 0x1979
LUCENT_SX8300P = 0x1C07
LUCENT_SX5363S = 0x1C0C
CUSEEME = 0x1F03
NTCSOFT_ALF2CM_ACM = 0x1FC4
DVM = 0x2000
DTS2 = 0x2001
MAKEAVIS = 0x3313
DIVIO_MPEG4_AAC = 0x4143
NOKIA_ADAPTIVE_MULTIRATE = 0x4201
DIVIO_G726 = 0x4243
LEAD_SPEECH = 0x434C
LEAD_VORBIS = 0x564C
WAVPACK_AUDIO = 0x5756
OGG_VORBIS_MODE_1 = 0x674F
OGG_VORBIS_MODE_2 = 0x6750
OGG_VORBIS_MODE_3 = 0x6751
OGG_VORBIS_MODE_1_PLUS = 0x676F
OGG_VORBIS_MODE_2_PLUS = 0x6770
OGG_VORBIS_MODE_3_PLUS = 0x6771
ALAC = 0x6C61
_3COM_NBX = 0x7000 # Can't have leading digit
OPUS = 0x704F
FAAD_AAC = 0x706D
AMR_NB = 0x7361
AMR_WB = 0x7362
AMR_WP = 0x7363
GSM_AMR_CBR = 0x7A21
GSM_AMR_VBR_SID = 0x7A22
COMVERSE_INFOSYS_G723_1 = 0xA100
COMVERSE_INFOSYS_AVQSBC = 0xA101
COMVERSE_INFOSYS_SBC = 0xA102
SYMBOL_G729_A = 0xA103
VOICEAGE_AMR_WB = 0xA104
INGENIENT_G726 = 0xA105
MPEG4_AAC = 0xA106
ENCORE_G726 = 0xA107
ZOLL_ASAO = 0xA108
SPEEX_VOICE = 0xA109
VIANIX_MASC = 0xA10A
WM9_SPECTRUM_ANALYZER = 0xA10B
WMF_SPECTRUM_ANAYZER = 0xA10C
GSM_610 = 0xA10D
GSM_620 = 0xA10E
GSM_660 = 0xA10F
GSM_690 = 0xA110
GSM_ADAPTIVE_MULTIRATE_WB = 0xA111
POLYCOM_G722 = 0xA112
POLYCOM_G728 = 0xA113
POLYCOM_G729_A = 0xA114
POLYCOM_SIREN = 0xA115
GLOBAL_IP_ILBC = 0xA116
RADIOTIME_TIME_SHIFT_RADIO = 0xA117
NICE_ACA = 0xA118
NICE_ADPCM = 0xA119
VOCORD_G721 = 0xA11A
VOCORD_G726 = 0xA11B
VOCORD_G722_1 = 0xA11C
VOCORD_G728 = 0xA11D
VOCORD_G729 = 0xA11E
VOCORD_G729_A = 0xA11F
VOCORD_G723_1 = 0xA120
VOCORD_LBC = 0xA121
NICE_G728 = 0xA122
FRACE_TELECOM_G729 = 0xA123
CODIAN = 0xA124
FLAC = 0xF1AC
EXTENSIBLE = 0xFFFE
DEVELOPMENT = 0xFFFF
KNOWN_WAVE_FORMATS = {WAVE_FORMAT.PCM, WAVE_FORMAT.IEEE_FLOAT}
# assumes file pointer is immediately
# after the 'fmt ' id
def _read_fmt_chunk(fid, is_big_endian):
"""
Returns
-------
size : int
size of format subchunk in bytes (minus 8 for "fmt " and itself)
format_tag : int
PCM, float, or compressed format
channels : int
number of channels
fs : int
sampling frequency in samples per second
bytes_per_second : int
overall byte rate for the file
block_align : int
bytes per sample, including all channels
bit_depth : int
bits per sample
"""
if is_big_endian:
fmt = '>'
else:
fmt = '<'
size = res = struct.unpack(fmt+'I', fid.read(4))[0]
bytes_read = 0
if size < 16:
raise ValueError("Binary structure of wave file is not compliant")
res = struct.unpack(fmt+'HHIIHH', fid.read(16))
bytes_read += 16
format_tag, channels, fs, bytes_per_second, block_align, bit_depth = res
if format_tag == WAVE_FORMAT.EXTENSIBLE and size >= (16+2):
ext_chunk_size = struct.unpack(fmt+'H', fid.read(2))[0]
bytes_read += 2
if ext_chunk_size >= 22:
extensible_chunk_data = fid.read(22)
bytes_read += 22
raw_guid = extensible_chunk_data[2+4:2+4+16]
# GUID template {XXXXXXXX-0000-0010-8000-00AA00389B71} (RFC-2361)
# MS GUID byte order: first three groups are native byte order,
# rest is Big Endian
if is_big_endian:
tail = b'\x00\x00\x00\x10\x80\x00\x00\xAA\x00\x38\x9B\x71'
else:
tail = b'\x00\x00\x10\x00\x80\x00\x00\xAA\x00\x38\x9B\x71'
if raw_guid.endswith(tail):
format_tag = struct.unpack(fmt+'I', raw_guid[:4])[0]
else:
raise ValueError("Binary structure of wave file is not compliant")
if format_tag not in KNOWN_WAVE_FORMATS:
try:
format_name = WAVE_FORMAT(format_tag).name
except ValueError:
format_name = f'{format_tag:#06x}'
raise ValueError(f"Unknown wave file format: {format_name}. Supported "
"formats: " +
', '.join(x.name for x in KNOWN_WAVE_FORMATS))
# move file pointer to next chunk
if size > (bytes_read):
fid.read(size - bytes_read)
return (size, format_tag, channels, fs, bytes_per_second, block_align,
bit_depth)
# assumes file pointer is immediately after the 'data' id
def _read_data_chunk(fid, format_tag, channels, bit_depth, is_big_endian,
mmap=False):
if is_big_endian:
fmt = '>I'
else:
fmt = '<I'
# Size of the data subchunk in bytes
size = struct.unpack(fmt, fid.read(4))[0]
# Number of bytes per sample
bytes_per_sample = bit_depth//8
if bit_depth == 8:
dtype = 'u1'
else:
if is_big_endian:
dtype = '>'
else:
dtype = '<'
if format_tag == WAVE_FORMAT.PCM:
dtype += 'i%d' % bytes_per_sample
else:
dtype += 'f%d' % bytes_per_sample
if not mmap:
data = numpy.frombuffer(fid.read(size), dtype=dtype)
else:
start = fid.tell()
data = numpy.memmap(fid, dtype=dtype, mode='c', offset=start,
shape=(size//bytes_per_sample,))
fid.seek(start + size)
if channels > 1:
data = data.reshape(-1, channels)
return data
def _skip_unknown_chunk(fid, is_big_endian):
if is_big_endian:
fmt = '>I'
else:
fmt = '<I'
data = fid.read(4)
# call unpack() and seek() only if we have really read data from file
# otherwise empty read at the end of the file would trigger
# unnecessary exception at unpack() call
# in case data equals somehow to 0, there is no need for seek() anyway
if data:
size = struct.unpack(fmt, data)[0]
fid.seek(size, 1)
def _read_riff_chunk(fid):
str1 = fid.read(4) # File signature
if str1 == b'RIFF':
is_big_endian = False
fmt = '<I'
elif str1 == b'RIFX':
is_big_endian = True
fmt = '>I'
else:
# There are also .wav files with "FFIR" or "XFIR" signatures?
raise ValueError(f"File format {repr(str1)} not understood. Only "
"'RIFF' and 'RIFX' supported.")
# Size of entire file
file_size = struct.unpack(fmt, fid.read(4))[0] + 8
str2 = fid.read(4)
if str2 != b'WAVE':
raise ValueError(f"Not a WAV file. RIFF form type is {repr(str2)}.")
return file_size, is_big_endian
def read(filename, mmap=False):
"""
Open a WAV file
Return the sample rate (in samples/sec) and data from a WAV file.
Parameters
----------
filename : string or open file handle
Input wav file.
mmap : bool, optional
Whether to read data as memory-mapped.
Only to be used on real files (Default: False).
.. versionadded:: 0.12.0
Returns
-------
rate : int
Sample rate of wav file.
data : numpy array
Data read from wav file. Data-type is determined from the file;
see Notes.
Notes
-----
This function cannot read wav files with 24-bit data.
Common data types: [1]_
===================== =========== =========== =============
WAV format Min Max NumPy dtype
===================== =========== =========== =============
32-bit floating-point -1.0 +1.0 float32
32-bit PCM -2147483648 +2147483647 int32
16-bit PCM -32768 +32767 int16
8-bit PCM 0 255 uint8
===================== =========== =========== =============
Note that 8-bit PCM is unsigned.
References
----------
.. [1] IBM Corporation and Microsoft Corporation, "Multimedia Programming
Interface and Data Specifications 1.0", section "Data Format of the
Samples", August 1991
http://www.tactilemedia.com/info/MCI_Control_Info.html
Examples
--------
>>> from os.path import dirname, join as pjoin
>>> from scipy.io import wavfile
>>> import scipy.io
Get the filename for an example .wav file from the tests/data directory.
>>> data_dir = pjoin(dirname(scipy.io.__file__), 'tests', 'data')
>>> wav_fname = pjoin(data_dir, 'test-44100Hz-2ch-32bit-float-be.wav')
Load the .wav file contents.
>>> samplerate, data = wavfile.read(wav_fname)
>>> print(f"number of channels = {data.shape[1]}")
number of channels = 2
>>> length = data.shape[0] / samplerate
>>> print(f"length = {length}s")
length = 0.01s
Plot the waveform.
>>> import matplotlib.pyplot as plt
>>> import numpy as np
>>> time = np.linspace(0., length, data.shape[0])
>>> plt.plot(time, data[:, 0], label="Left channel")
>>> plt.plot(time, data[:, 1], label="Right channel")
>>> plt.legend()
>>> plt.xlabel("Time [s]")
>>> plt.ylabel("Amplitude")
>>> plt.show()
"""
if hasattr(filename, 'read'):
fid = filename
mmap = False
else:
fid = open(filename, 'rb')
try:
file_size, is_big_endian = _read_riff_chunk(fid)
fmt_chunk_received = False
data_chunk_received = False
channels = 1
bit_depth = 8
format_tag = WAVE_FORMAT.PCM
while fid.tell() < file_size:
# read the next chunk
chunk_id = fid.read(4)
if not chunk_id:
if data_chunk_received:
# End of file but data successfully read
warnings.warn(
"Reached EOF prematurely; finished at {:d} bytes, "
"expected {:d} bytes from header."
.format(fid.tell(), file_size),
WavFileWarning, stacklevel=2)
break
else:
raise ValueError("Unexpected end of file.")
elif len(chunk_id) < 4:
msg = f"Incomplete chunk ID: {repr(chunk_id)}"
# If we have the data, ignore the broken chunk
if fmt_chunk_received and data_chunk_received:
warnings.warn(msg + ", ignoring it.", WavFileWarning,
stacklevel=2)
else:
raise ValueError(msg)
if chunk_id == b'fmt ':
fmt_chunk_received = True
fmt_chunk = _read_fmt_chunk(fid, is_big_endian)
format_tag, channels, fs = fmt_chunk[1:4]
bit_depth = fmt_chunk[6]
if bit_depth not in {8, 16, 32, 64, 96, 128}:
raise ValueError("Unsupported bit depth: the wav file "
"has {}-bit data.".format(bit_depth))
elif chunk_id == b'fact':
_skip_unknown_chunk(fid, is_big_endian)
elif chunk_id == b'data':
data_chunk_received = True
if not fmt_chunk_received:
raise ValueError("No fmt chunk before data")
data = _read_data_chunk(fid, format_tag, channels, bit_depth,
is_big_endian, mmap)
elif chunk_id == b'LIST':
# Someday this could be handled properly but for now skip it
_skip_unknown_chunk(fid, is_big_endian)
elif chunk_id in {b'JUNK', b'Fake'}:
# Skip alignment chunks without warning
_skip_unknown_chunk(fid, is_big_endian)
else:
warnings.warn("Chunk (non-data) not understood, skipping it.",
WavFileWarning, stacklevel=2)
_skip_unknown_chunk(fid, is_big_endian)
finally:
if not hasattr(filename, 'read'):
fid.close()
else:
fid.seek(0)
return fs, data
def write(filename, rate, data):
"""
Write a NumPy array as a WAV file.
Parameters
----------
filename : string or open file handle
Output wav file.
rate : int
The sample rate (in samples/sec).
data : ndarray
A 1-D or 2-D NumPy array of either integer or float data-type.
Notes
-----
* Writes a simple uncompressed WAV file.
* To write multiple-channels, use a 2-D array of shape
(Nsamples, Nchannels).
* The bits-per-sample and PCM/float will be determined by the data-type.
Common data types: [1]_
===================== =========== =========== =============
WAV format Min Max NumPy dtype
===================== =========== =========== =============
32-bit floating-point -1.0 +1.0 float32
32-bit PCM -2147483648 +2147483647 int32
16-bit PCM -32768 +32767 int16
8-bit PCM 0 255 uint8
===================== =========== =========== =============
Note that 8-bit PCM is unsigned.
References
----------
.. [1] IBM Corporation and Microsoft Corporation, "Multimedia Programming
Interface and Data Specifications 1.0", section "Data Format of the
Samples", August 1991
http://www.tactilemedia.com/info/MCI_Control_Info.html
Examples
--------
Create a 100Hz sine wave, sampled at 44100Hz.
Write to 16-bit PCM, Mono.
>>> from scipy.io.wavfile import write
>>> samplerate = 44100; fs = 100
>>> t = np.linspace(0., 1., samplerate)
>>> amplitude = np.iinfo(np.int16).max
>>> data = amplitude * np.sin(2. * np.pi * fs * t)
>>> write("example.wav", samplerate, data)
"""
if hasattr(filename, 'write'):
fid = filename
else:
fid = open(filename, 'wb')
fs = rate
try:
dkind = data.dtype.kind
if not (dkind == 'i' or dkind == 'f' or (dkind == 'u' and
data.dtype.itemsize == 1)):
raise ValueError("Unsupported data type '%s'" % data.dtype)
header_data = b''
header_data += b'RIFF'
header_data += b'\x00\x00\x00\x00'
header_data += b'WAVE'
# fmt chunk
header_data += b'fmt '
if dkind == 'f':
format_tag = WAVE_FORMAT.IEEE_FLOAT
else:
format_tag = WAVE_FORMAT.PCM
if data.ndim == 1:
channels = 1
else:
channels = data.shape[1]
bit_depth = data.dtype.itemsize * 8
bytes_per_second = fs*(bit_depth // 8)*channels
block_align = channels * (bit_depth // 8)
fmt_chunk_data = struct.pack('<HHIIHH', format_tag, channels, fs,
bytes_per_second, block_align, bit_depth)
if not (dkind == 'i' or dkind == 'u'):
# add cbSize field for non-PCM files
fmt_chunk_data += b'\x00\x00'
header_data += struct.pack('<I', len(fmt_chunk_data))
header_data += fmt_chunk_data
# fact chunk (non-PCM files)
if not (dkind == 'i' or dkind == 'u'):
header_data += b'fact'
header_data += struct.pack('<II', 4, data.shape[0])
# check data size (needs to be immediately before the data chunk)
if ((len(header_data)-4-4) + (4+4+data.nbytes)) > 0xFFFFFFFF:
raise ValueError("Data exceeds wave file size limit")
fid.write(header_data)
# data chunk
fid.write(b'data')
fid.write(struct.pack('<I', data.nbytes))
if data.dtype.byteorder == '>' or (data.dtype.byteorder == '=' and
sys.byteorder == 'big'):
data = data.byteswap()
_array_tofile(fid, data)
# Determine file size and place it in correct
# position at start of the file.
size = fid.tell()
fid.seek(4)
fid.write(struct.pack('<I', size-8))
finally:
if not hasattr(filename, 'write'):
fid.close()
else:
fid.seek(0)
def _array_tofile(fid, data):
# ravel gives a c-contiguous buffer
fid.write(data.ravel().view('b').data)