SoundFile 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+. SoundFile represents audio data as NumPy arrays.
SoundFile 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 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 SoundFile 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.
Data can be written to the file using soundfile.write(), or read from the file using soundfile.read(). SoundFile 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.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.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.
Pysoundfile 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, Pysoundfile 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.
- 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
- Documentation overhaul and hosting on readthedocs.
- 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.
- 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
SoundFile.buffer_write, which read/write raw data without involving Numpy.
infofunction that returns metadata of a sound file.
- Changed the argument order of the
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
SoundFile.framesin favor of now-deprecated
- Improves performance of
- Improves import time by using CFFI's out of line mode.
- Adds a build script for building distributions.