python-soundfile
The soundfile module is an audio library based on libsndfile, CFFI and NumPy. Full documentation is available on https://python-soundfile.readthedocs.io/.
The soundfile
module can read and write sound files. File reading/writing is
supported through libsndfile,
which is a free, cross-platform, open-source (LGPL) library for reading
and writing many different sampled sound file formats that runs on many
platforms including Windows, OS X, and Unix. It is accessed through
CFFI, which is a foreign function
interface for Python calling C code. CFFI is supported for CPython 2.6+,
3.x and PyPy 2.0+. The soundfile
module represents audio data as NumPy arrays.
Breaking Changes
The soundfile
module has evolved rapidly during the last few releases. Most
notably, we changed the import name from import pysoundfile
to
import soundfile
in 0.7. In 0.6, we cleaned up many small
inconsistencies, particularly in the the ordering and naming of
function arguments and the removal of the indexing interface.
In 0.8.0, we changed the default value of always_2d
from True
to False
. Also, the order of arguments of the write
function
changed from write(data, file, ...)
to write(file, data, ...)
.
In 0.9.0, we changed the ctype
arguments of the buffer_*
methods to dtype
, using the Numpy dtype
notation. The old
ctype
arguments still work, but are now officially deprecated.
Installation
The soundfile
module depends on the Python packages CFFI and NumPy, and the
system library libsndfile.
In a modern Python, you can use pip install soundfile
to download
and install the latest release of the soundfile
module and its dependencies.
On Windows and OS X, this will also install the library libsndfile.
On Linux, you need to install libsndfile using your distribution’s
package manager, for example sudo apt-get install libsndfile1
.
If you are running on an unusual platform or if you are using an older version of Python, you might need to install NumPy and CFFI separately, for example using the Anaconda package manager or the Unofficial Windows Binaries for Python Extension Packages.
Error Reporting
In case of API usage errors the soundfile
module raises the usual ValueError
or TypeError
.
For other errors SoundFileError
is raised (used to be RuntimeError
).
Particularly, a LibsndfileError
subclass of this exception is raised on
errors reported by the libsndfile library. In that case the exception object
provides the libsndfile internal error code in the LibsndfileError.code
attribute and the raw
libsndfile error message in the LibsndfileError.error_string
attribute.
Read/Write Functions
Data can be written to the file using soundfile.write()
, or read from
the file using soundfile.read()
. The soundfile
module can open all file formats
that libsndfile supports, for example WAV,
FLAC, OGG and MAT files (see Known Issues below about writing OGG files).
Here is an example for a program that reads a wave file and copies it into an FLAC file:
import soundfile as sf
data, samplerate = sf.read('existing_file.wav')
sf.write('new_file.flac', data, samplerate)
Block Processing
Sound files can also be read in short, optionally overlapping blocks
with soundfile.blocks()
.
For example, this calculates the signal level for each block of a long
file:
import numpy as np
import soundfile as sf
rms = [np.sqrt(np.mean(block**2)) for block in
sf.blocks('myfile.wav', blocksize=1024, overlap=512)]
SoundFile
Objects
Sound files can also be opened as SoundFile
objects. Every
SoundFile
has a specific sample rate, data format and a set number of
channels.
If a file is opened, it is kept open for as long as the SoundFile
object exists. The file closes when the object is garbage collected,
but you should use the SoundFile.close()
method or the
context manager to close the file explicitly:
import soundfile as sf
with sf.SoundFile('myfile.wav', 'r+') as f:
while f.tell() < f.frames:
pos = f.tell()
data = f.read(1024)
f.seek(pos)
f.write(data*2)
All data access uses frames as index. A frame is one discrete time-step in the sound file. Every frame contains as many samples as there are channels in the file.
RAW Files
soundfile.read()
can usually auto-detect the file type of sound files. This
is not possible for RAW files, though:
import soundfile as sf
data, samplerate = sf.read('myfile.raw', channels=1, samplerate=44100,
subtype='FLOAT')
Note that on x86, this defaults to endian='LITTLE'
. If you are
reading big endian data (mostly old PowerPC/6800-based files), you
have to set endian='BIG'
accordingly.
You can write RAW files in a similar way, but be advised that in most cases, a more expressive format is better and should be used instead.
Virtual IO
If you have an open file-like object, soundfile.read()
can open it just like
regular files:
import soundfile as sf
with open('filename.flac', 'rb') as f:
data, samplerate = sf.read(f)
Here is an example using an HTTP request:
import io
import soundfile as sf
from urllib.request import urlopen
url = "http://tinyurl.com/shepard-risset"
data, samplerate = sf.read(io.BytesIO(urlopen(url).read()))
Note that the above example only works with Python 3.x. For Python 2.x support, replace the third line with:
from urllib2 import urlopen
Known Issues
Writing to OGG files can result in empty files with certain versions of libsndfile. See #130 for news on this issue.
If using a Buildroot style system, Python has trouble locating libsndfile.so
file, which causes python-soundfile to not be loaded. This is apparently a bug in python. For the time being, in soundfile.py
, you can remove the call to _find_library
and hardcode the location of the libsndfile.so
in _ffi.dlopen
. See #258 for discussion on this issue.
News
- 2013-08-27 V0.1.0 Bastian Bechtold:
Initial prototype. A simple wrapper for libsndfile in Python
- 2013-08-30 V0.2.0 Bastian Bechtold:
Bugfixes and more consistency with PySoundCard
- 2013-08-30 V0.2.1 Bastian Bechtold:
Bugfixes
- 2013-09-27 V0.3.0 Bastian Bechtold:
Added binary installer for Windows, and context manager
- 2013-11-06 V0.3.1 Bastian Bechtold:
Switched from distutils to setuptools for easier installation
- 2013-11-29 V0.4.0 Bastian Bechtold:
Thanks to David Blewett, now with Virtual IO!
- 2013-12-08 V0.4.1 Bastian Bechtold:
Thanks to Xidorn Quan, FLAC files are not float32 any more.
- 2014-02-26 V0.5.0 Bastian Bechtold:
Thanks to Matthias Geier, improved seeking and a flush() method.
- 2015-01-19 V0.6.0 Bastian Bechtold:
A big, big thank you to Matthias Geier, who did most of the work!
- 2015-04-12 V0.7.0 Bastian Bechtold:
Again, thanks to Matthias Geier for all of his hard work, but also Nils Werner and Whistler7 for their many suggestions and help.
Renamed
import pysoundfile
toimport soundfile
.Installation through pip wheels that contain the necessary libraries for OS X and Windows.
Removed
exclusive_creation
argument towrite()
.Added
truncate()
method.
- 2015-10-20 V0.8.0 Bastian Bechtold:
Again, Matthias Geier contributed a whole lot of hard work to this release.
Changed the default value of
always_2d
fromTrue
toFalse
.Numpy is now optional, and only loaded for
read
andwrite
.Added
SoundFile.buffer_read()
andSoundFile.buffer_read_into()
andSoundFile.buffer_write()
, which read/write raw data without involving Numpy.Added
info()
function that returns metadata of a sound file.Changed the argument order of the
write()
function fromwrite(data, file, ...)
towrite(file, data, ...)
And many more minor bug fixes.
- 2017-02-02 V0.9.0 Bastian Bechtold:
Thank you, Matthias Geier, Tomas Garcia, and Todd, for contributions for this release.
Adds support for ALAC files.
Adds new member
__libsndfile_version__
Adds number of frames to
info
classAdds
dtype
argument tobuffer_*
methodsDeprecates
ctype
argument tobuffer_*
methodsAdds official support for Python 3.6
And some minor bug fixes.
- 2017-11-12 V0.10.0 Bastian Bechtold:
Thank you, Matthias Geier, Toni Barth, Jon Peirce, Till Hoffmann, and Tomas Garcia, for contributions to this release.
Should now work with cx_freeze.
Several documentation fixes in the README.
Removes deprecated
ctype
argument in favor ofdtype
inbuffer_*()
.Adds
SoundFile.frames
in favor of now-deprecated__len__()
.Improves performance of
blocks()
andSoundFile.blocks()
.Improves import time by using CFFI’s out of line mode.
Adds a build script for building distributions.
- 2022-06-02 V0.11.0 Bastian Bechtold:
Thank you, tennies, Hannes Helmholz, Christoph Boeddeker, Matt Vollrath, Matthias Geier, Jacek Konieczny, Boris Verkhovskiy, Jonas Haag, Eduardo Moguillansky, Panos Laganakos, Jarvy Jarvison, Domingo Ramirez, Tim Chagnon, Kyle Benesch, Fabian-Robert Stöter, Joe Todd
MP3 support
Adds binary wheels for macOS M1
Improves compatibility with macOS, specifically for M1 machines
Fixes file descriptor open for binary wheels on Windows and Python 3.5+
Updates libsndfile to v1.1.0
Adds get_strings method for retrieving all metadata at once
Improves documentation, error messages and tests
Displays length of very short files in samples
Supports the file system path protocol (pathlib et al)
Contributing
If you find bugs, errors, omissions or other things that need improvement, please create an issue or a pull request at https://github.com/bastibe/python-soundfile/. Contributions are always welcome!
Testing
If you fix a bug, you should add a test that exposes the bug (to avoid future regressions), if you add a feature, you should add tests for it as well.
To run the tests, use:
python setup.py test
This uses py.test; if you haven’t installed it already, it will be downloaded and installed for you.
Note
There is a known problem that prohibits the use of file descriptors on Windows if the libsndfile DLL was compiled with a different compiler than the Python interpreter. Unfortunately, this is typically the case if the packaged DLLs are used. To skip the tests which utilize file descriptors, use:
python setup.py test --pytest-args="-knot\ fd"
Coverage
If you want to measure code coverage, you can use coverage.py. Just install it with:
pip install coverage --user
… and run it with:
coverage run --source soundfile.py -m py.test
coverage html
The resulting HTML files will be written to the htmlcov/
directory.
You can even check branch coverage:
coverage run --branch --source soundfile.py -m py.test
coverage html
Documentation
If you make changes to the documentation, you can re-create the HTML pages on your local system using Sphinx.
You can install it and a few other necessary packages with:
pip install -r doc/requirements.txt --user
To create the HTML pages, use:
python setup.py build_sphinx
The generated files will be available in the directory build/sphinx/html/
.
API Documentation
python-soundfile is an audio library based on libsndfile, CFFI and NumPy.
Sound files can be read or written directly using the functions
read()
and write()
.
To read a sound file in a block-wise fashion, use blocks()
.
Alternatively, sound files can be opened as SoundFile
objects.
For further information, see https://python-soundfile.readthedocs.io/.
- soundfile.read(file, frames=-1, start=0, stop=None, dtype='float64', always_2d=False, fill_value=None, out=None, samplerate=None, channels=None, format=None, subtype=None, endian=None, closefd=True)[source]
Provide audio data from a sound file as NumPy array.
By default, the whole file is read from the beginning, but the position to start reading can be specified with start and the number of frames to read can be specified with frames. Alternatively, a range can be specified with start and stop.
If there is less data left in the file than requested, the rest of the frames are filled with fill_value. If no fill_value is specified, a smaller array is returned.
- Parameters:
file (str or int or file-like object) – The file to read from. See
SoundFile
for details.frames (int, optional) – The number of frames to read. If frames is negative, the whole rest of the file is read. Not allowed if stop is given.
start (int, optional) – Where to start reading. A negative value counts from the end.
stop (int, optional) – The index after the last frame to be read. A negative value counts from the end. Not allowed if frames is given.
dtype ({'float64', 'float32', 'int32', 'int16'}, optional) –
Data type of the returned array, by default
'float64'
. Floating point audio data is typically in the range from-1.0
to1.0
. Integer data is in the range from-2**15
to2**15-1
for'int16'
and from-2**31
to2**31-1
for'int32'
.Note
Reading int values from a float file will not scale the data to [-1.0, 1.0). If the file contains
np.array([42.6], dtype='float32')
, you will readnp.array([43], dtype='int32')
fordtype='int32'
.always_2d (bool, optional) – By default, reading a mono sound file will return a one-dimensional array. With
always_2d=True
, audio data is always returned as a two-dimensional array, even if the audio file has only one channel.fill_value (float, optional) – If more frames are requested than available in the file, the rest of the output is be filled with fill_value. If fill_value is not specified, a smaller array is returned.
out (
numpy.ndarray
or subclass, optional) – If out is specified, the data is written into the given array instead of creating a new array. In this case, the arguments dtype and always_2d are silently ignored! If frames is not given, it is obtained from the length of out.samplerate – See
SoundFile
.channels – See
SoundFile
.format – See
SoundFile
.subtype – See
SoundFile
.endian – See
SoundFile
.closefd – See
SoundFile
.
- Returns:
audiodata (
numpy.ndarray
or type(out)) – A two-dimensional (frames x channels) NumPy array is returned. If the sound file has only one channel, a one-dimensional array is returned. Usealways_2d=True
to return a two-dimensional array anyway.If out was specified, it is returned. If out has more frames than available in the file (or if frames is smaller than the length of out) and no fill_value is given, then only a part of out is overwritten and a view containing all valid frames is returned.
samplerate (int) – The sample rate of the audio file.
Examples
>>> import soundfile as sf >>> data, samplerate = sf.read('stereo_file.wav') >>> data array([[ 0.71329652, 0.06294799], [-0.26450912, -0.38874483], ... [ 0.67398441, -0.11516333]]) >>> samplerate 44100
- soundfile.write(file, data, samplerate, subtype=None, endian=None, format=None, closefd=True)[source]
Write data to a sound file.
Note
If file exists, it will be truncated and overwritten!
- Parameters:
file (str or int or file-like object) – The file to write to. See
SoundFile
for details.data (array_like) –
The data to write. Usually two-dimensional (frames x channels), but one-dimensional data can be used for mono files. Only the data types
'float64'
,'float32'
,'int32'
and'int16'
are supported.Note
The data type of data does not select the data type of the written file. Audio data will be converted to the given subtype. Writing int values to a float file will not scale the values to [-1.0, 1.0). If you write the value
np.array([42], dtype='int32')
, to asubtype='FLOAT'
file, the file will then containnp.array([42.], dtype='float32')
.samplerate (int) – The sample rate of the audio data.
subtype (str, optional) – See
default_subtype()
for the default value andavailable_subtypes()
for all possible values.format – See
SoundFile
.endian – See
SoundFile
.closefd – See
SoundFile
.
Examples
Write 10 frames of random data to a new file:
>>> import numpy as np >>> import soundfile as sf >>> sf.write('stereo_file.wav', np.random.randn(10, 2), 44100, 'PCM_24')
- soundfile.blocks(file, blocksize=None, overlap=0, frames=-1, start=0, stop=None, dtype='float64', always_2d=False, fill_value=None, out=None, samplerate=None, channels=None, format=None, subtype=None, endian=None, closefd=True)[source]
Return a generator for block-wise reading.
By default, iteration starts at the beginning and stops at the end of the file. Use start to start at a later position and frames or stop to stop earlier.
If you stop iterating over the generator before it’s exhausted, the sound file is not closed. This is normally not a problem because the file is opened in read-only mode. To close the file properly, the generator’s
close()
method can be called.- Parameters:
file (str or int or file-like object) – The file to read from. See
SoundFile
for details.blocksize (int) – The number of frames to read per block. Either this or out must be given.
overlap (int, optional) – The number of frames to rewind between each block.
frames – See
read()
.start – See
read()
.stop – See
read()
.dtype ({'float64', 'float32', 'int32', 'int16'}, optional) – See
read()
.always_2d – See
read()
.fill_value – See
read()
.out – See
read()
.samplerate – See
SoundFile
.channels – See
SoundFile
.format – See
SoundFile
.subtype – See
SoundFile
.endian – See
SoundFile
.closefd – See
SoundFile
.
- Yields:
numpy.ndarray
or type(out) – Blocks of audio data. If out was given, and the requested frames are not an integer multiple of the length of out, and no fill_value was given, the last block will be a smaller view into out.
Examples
>>> import soundfile as sf >>> for block in sf.blocks('stereo_file.wav', blocksize=1024): >>> pass # do something with 'block'
- soundfile.info(file, verbose=False)[source]
Returns an object with information about a
SoundFile
.- Parameters:
verbose (bool) – Whether to print additional information.
- soundfile.available_formats()[source]
Return a dictionary of available major formats.
Examples
>>> import soundfile as sf >>> sf.available_formats() {'FLAC': 'FLAC (FLAC Lossless Audio Codec)', 'OGG': 'OGG (OGG Container format)', 'WAV': 'WAV (Microsoft)', 'AIFF': 'AIFF (Apple/SGI)', ... 'WAVEX': 'WAVEX (Microsoft)', 'RAW': 'RAW (header-less)', 'MAT5': 'MAT5 (GNU Octave 2.1 / Matlab 5.0)'}
- soundfile.available_subtypes(format=None)[source]
Return a dictionary of available subtypes.
- Parameters:
format (str) – If given, only compatible subtypes are returned.
Examples
>>> import soundfile as sf >>> sf.available_subtypes('FLAC') {'PCM_24': 'Signed 24 bit PCM', 'PCM_16': 'Signed 16 bit PCM', 'PCM_S8': 'Signed 8 bit PCM'}
- soundfile.check_format(format, subtype=None, endian=None)[source]
Check if the combination of format/subtype/endian is valid.
Examples
>>> import soundfile as sf >>> sf.check_format('WAV', 'PCM_24') True >>> sf.check_format('FLAC', 'VORBIS') False
- soundfile.default_subtype(format)[source]
Return the default subtype for a given format.
Examples
>>> import soundfile as sf >>> sf.default_subtype('WAV') 'PCM_16' >>> sf.default_subtype('MAT5') 'DOUBLE'
- class soundfile.SoundFile(file, mode='r', samplerate=None, channels=None, subtype=None, endian=None, format=None, closefd=True)[source]
Open a sound file.
If a file is opened with
mode
'r'
(the default) or'r+'
, no sample rate, channels or file format need to be given because the information is obtained from the file. An exception is the'RAW'
data format, which always requires these data points.File formats consist of three case-insensitive strings:
a major format which is by default obtained from the extension of the file name (if known) and which can be forced with the format argument (e.g.
format='WAVEX'
).a subtype, e.g.
'PCM_24'
. Most major formats have a default subtype which is used if no subtype is specified.an endian-ness, which doesn’t have to be specified at all in most cases.
A
SoundFile
object is a context manager, which means if used in a “with” statement,close()
is automatically called when reaching the end of the code block inside the “with” statement.- Parameters:
file (str or int or file-like object) – The file to open. This can be a file name, a file descriptor or a Python file object (or a similar object with the methods
read()
/readinto()
,write()
,seek()
andtell()
).mode ({'r', 'r+', 'w', 'w+', 'x', 'x+'}, optional) – Open mode. Has to begin with one of these three characters:
'r'
for reading,'w'
for writing (truncates file) or'x'
for writing (raises an error if file already exists). Additionally, it may contain'+'
to open file for both reading and writing. The character'b'
for binary mode is implied because all sound files have to be opened in this mode. If file is a file descriptor or a file-like object,'w'
doesn’t truncate and'x'
doesn’t raise an error.samplerate (int) – The sample rate of the file. If
mode
contains'r'
, this is obtained from the file (except for'RAW'
files).channels (int) – The number of channels of the file. If
mode
contains'r'
, this is obtained from the file (except for'RAW'
files).subtype (str, sometimes optional) – The subtype of the sound file. If
mode
contains'r'
, this is obtained from the file (except for'RAW'
files), if not, the default value depends on the selectedformat
(seedefault_subtype()
). Seeavailable_subtypes()
for all possible subtypes for a givenformat
.endian ({'FILE', 'LITTLE', 'BIG', 'CPU'}, sometimes optional) – The endian-ness of the sound file. If
mode
contains'r'
, this is obtained from the file (except for'RAW'
files), if not, the default value is'FILE'
, which is correct in most cases.format (str, sometimes optional) – The major format of the sound file. If
mode
contains'r'
, this is obtained from the file (except for'RAW'
files), if not, the default value is determined from the file extension. Seeavailable_formats()
for all possible values.closefd (bool, optional) – Whether to close the file descriptor on
close()
. Only applicable if the file argument is a file descriptor.
Examples
>>> from soundfile import SoundFile
Open an existing file for reading:
>>> myfile = SoundFile('existing_file.wav') >>> # do something with myfile >>> myfile.close()
Create a new sound file for reading and writing using a with statement:
>>> with SoundFile('new_file.wav', 'x+', 44100, 2) as myfile: >>> # do something with myfile >>> # ... >>> assert not myfile.closed >>> # myfile.close() is called automatically at the end >>> assert myfile.closed
- property name
The file name of the sound file.
- property mode
The open mode the sound file was opened with.
- property samplerate
The sample rate of the sound file.
- property frames
The number of frames in the sound file.
- property channels
The number of channels in the sound file.
- property format
The major format of the sound file.
- property subtype
The subtype of data in the the sound file.
- property endian
The endian-ness of the data in the sound file.
- property format_info
A description of the major format of the sound file.
- property subtype_info
A description of the subtype of the sound file.
- property sections
The number of sections of the sound file.
- property closed
Whether the sound file is closed or not.
- property extra_info
Retrieve the log string generated when opening the file.
- seek(frames, whence=0)[source]
Set the read/write position.
- Parameters:
frames (int) – The frame index or offset to seek.
whence ({SEEK_SET, SEEK_CUR, SEEK_END}, optional) – By default (
whence=SEEK_SET
), frames are counted from the beginning of the file.whence=SEEK_CUR
seeks from the current position (positive and negative values are allowed for frames).whence=SEEK_END
seeks from the end (use negative value for frames).
- Returns:
int – The new absolute read/write position in frames.
Examples
>>> from soundfile import SoundFile, SEEK_END >>> myfile = SoundFile('stereo_file.wav')
Seek to the beginning of the file:
>>> myfile.seek(0) 0
Seek to the end of the file:
>>> myfile.seek(0, SEEK_END) 44100 # this is the file length
- read(frames=-1, dtype='float64', always_2d=False, fill_value=None, out=None)[source]
Read from the file and return data as NumPy array.
Reads the given number of frames in the given data format starting at the current read/write position. This advances the read/write position by the same number of frames. By default, all frames from the current read/write position to the end of the file are returned. Use
seek()
to move the current read/write position.- Parameters:
frames (int, optional) – The number of frames to read. If
frames < 0
, the whole rest of the file is read.dtype ({'float64', 'float32', 'int32', 'int16'}, optional) –
Data type of the returned array, by default
'float64'
. Floating point audio data is typically in the range from-1.0
to1.0
. Integer data is in the range from-2**15
to2**15-1
for'int16'
and from-2**31
to2**31-1
for'int32'
.Note
Reading int values from a float file will not scale the data to [-1.0, 1.0). If the file contains
np.array([42.6], dtype='float32')
, you will readnp.array([43], dtype='int32')
fordtype='int32'
.always_2d (bool, optional) – By default, reading a mono sound file will return a one-dimensional array. With
always_2d=True
, audio data is always returned as a two-dimensional array, even if the audio file has only one channel.fill_value (float, optional) – If more frames are requested than available in the file, the rest of the output is be filled with fill_value. If fill_value is not specified, a smaller array is returned.
out (
numpy.ndarray
or subclass, optional) – If out is specified, the data is written into the given array instead of creating a new array. In this case, the arguments dtype and always_2d are silently ignored! If frames is not given, it is obtained from the length of out.
- Returns:
audiodata (
numpy.ndarray
or type(out)) – A two-dimensional NumPy (frames x channels) array is returned. If the sound file has only one channel, a one-dimensional array is returned. Usealways_2d=True
to return a two-dimensional array anyway.If out was specified, it is returned. If out has more frames than available in the file (or if frames is smaller than the length of out) and no fill_value is given, then only a part of out is overwritten and a view containing all valid frames is returned.
Examples
>>> from soundfile import SoundFile >>> myfile = SoundFile('stereo_file.wav')
Reading 3 frames from a stereo file:
>>> myfile.read(3) array([[ 0.71329652, 0.06294799], [-0.26450912, -0.38874483], [ 0.67398441, -0.11516333]]) >>> myfile.close()
See also
- buffer_read(frames=-1, dtype=None)[source]
Read from the file and return data as buffer object.
Reads the given number of frames in the given data format starting at the current read/write position. This advances the read/write position by the same number of frames. By default, all frames from the current read/write position to the end of the file are returned. Use
seek()
to move the current read/write position.- Parameters:
frames (int, optional) – The number of frames to read. If
frames < 0
, the whole rest of the file is read.dtype ({'float64', 'float32', 'int32', 'int16'}) – Audio data will be converted to the given data type.
- Returns:
buffer – A buffer containing the read data.
See also
- buffer_read_into(buffer, dtype)[source]
Read from the file into a given buffer object.
Fills the given buffer with frames in the given data format starting at the current read/write position (which can be changed with
seek()
) until the buffer is full or the end of the file is reached. This advances the read/write position by the number of frames that were read.- Parameters:
buffer (writable buffer) – Audio frames from the file are written to this buffer.
dtype ({'float64', 'float32', 'int32', 'int16'}) – The data type of buffer.
- Returns:
int – The number of frames that were read from the file. This can be less than the size of buffer. The rest of the buffer is not filled with meaningful data.
See also
- write(data)[source]
Write audio data from a NumPy array to the file.
Writes a number of frames at the read/write position to the file. This also advances the read/write position by the same number of frames and enlarges the file if necessary.
Note that writing int values to a float file will not scale the values to [-1.0, 1.0). If you write the value
np.array([42], dtype='int32')
, to asubtype='FLOAT'
file, the file will then containnp.array([42.], dtype='float32')
.- Parameters:
data (array_like) –
The data to write. Usually two-dimensional (frames x channels), but one-dimensional data can be used for mono files. Only the data types
'float64'
,'float32'
,'int32'
and'int16'
are supported.Note
The data type of data does not select the data type of the written file. Audio data will be converted to the given subtype. Writing int values to a float file will not scale the values to [-1.0, 1.0). If you write the value
np.array([42], dtype='int32')
, to asubtype='FLOAT'
file, the file will then containnp.array([42.], dtype='float32')
.
Examples
>>> import numpy as np >>> from soundfile import SoundFile >>> myfile = SoundFile('stereo_file.wav')
Write 10 frames of random data to a new file:
>>> with SoundFile('stereo_file.wav', 'w', 44100, 2, 'PCM_24') as f: >>> f.write(np.random.randn(10, 2))
See also
- buffer_write(data, dtype)[source]
Write audio data from a buffer/bytes object to the file.
Writes the contents of data to the file at the current read/write position. This also advances the read/write position by the number of frames that were written and enlarges the file if necessary.
- Parameters:
data (buffer or bytes) – A buffer or bytes object containing the audio data to be written.
dtype ({'float64', 'float32', 'int32', 'int16'}) – The data type of the audio data stored in data.
See also
- blocks(blocksize=None, overlap=0, frames=-1, dtype='float64', always_2d=False, fill_value=None, out=None)[source]
Return a generator for block-wise reading.
By default, the generator yields blocks of the given blocksize (using a given overlap) until the end of the file is reached; frames can be used to stop earlier.
- Parameters:
blocksize (int) – The number of frames to read per block. Either this or out must be given.
overlap (int, optional) – The number of frames to rewind between each block.
frames (int, optional) – The number of frames to read. If
frames < 0
, the file is read until the end.dtype ({'float64', 'float32', 'int32', 'int16'}, optional) – See
read()
.always_2d – See
read()
.out (
numpy.ndarray
or subclass, optional) – Seeread()
.fill_value – See
read()
.out – If out is specified, the data is written into the given array instead of creating a new array. In this case, the arguments dtype and always_2d are silently ignored!
- Yields:
numpy.ndarray
or type(out) – Blocks of audio data. If out was given, and the requested frames are not an integer multiple of the length of out, and no fill_value was given, the last block will be a smaller view into out.
Examples
>>> from soundfile import SoundFile >>> with SoundFile('stereo_file.wav') as f: >>> for block in f.blocks(blocksize=1024): >>> pass # do something with 'block'
- truncate(frames=None)[source]
Truncate the file to a given number of frames.
After this command, the read/write position will be at the new end of the file.
- Parameters:
frames (int, optional) – Only the data before frames is kept, the rest is deleted. If not specified, the current read/write position is used.
- flush()[source]
Write unwritten data to the file system.
Data written with
write()
is not immediately written to the file system but buffered in memory to be written at a later time. Callingflush()
makes sure that all changes are actually written to the file system.This has no effect on files opened in read-only mode.
- exception soundfile.SoundFileRuntimeError[source]
soundfile module runtime error.
Errors that used to be
RuntimeError
.