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.
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
False. Also, the order of arguments of the
write(data, file, ...) to
write(file, data, ...).
In 0.9.0, we changed the
ctype arguments of the
dtype, using the Numpy
dtype notation. The old
ctype arguments still work, but are now officially deprecated.
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.
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.
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)
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)]
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.
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
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.
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
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
_ffi.dlopen. See #258 for discussion on this issue.
- 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:
- 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!
- Switched to
float64as default data type.
- Function arguments changed for consistency.
- Added unit tests.
- Added global read(), write(), blocks() convenience functions.
- Documentation overhaul and hosting on readthedocs.
- Added tell() method.
- Switched to
- 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.
- Installation through pip wheels that contain the necessary libraries for OS X and Windows.
exclusive_creationargument to write().
- 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
- Numpy is now optional, and only loaded for
- Added SoundFile.buffer_read() and SoundFile.buffer_read_into() and SoundFile.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 from
write(data, file, ...)to
write(file, data, ...)
And many more minor bug fixes.
- Changed the default value of
- 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
- Adds number of frames to
- Adds 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
ctypeargument in favor of
- Adds SoundFile.frames in favor of now-deprecated
- Improves performance of blocks() and SoundFile.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)