PySoundFile is an audio library based on libsndfile, CFFI and Numpy. Full documentation is available on http://pysoundfile.readthedocs.org/.
PySoundFile 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+. PySoundFile represents audio data as NumPy arrays.
The latest release of PySoundFile cleans up many small inconsistencies, particularly in the the ordering and naming of function arguments. Therefore, old code will probably not work any more.
It also adds a number of great new features, such as global read
and write functions that do not require you to open a
SoundFile, or a blocks function that can read a sound file one
block at a time. It has also grown a lot more flexible and powerful at
opening things like streams, buffers, or file descriptors.
With all these improvements, we feel that the indexing interface is not needed any more. It is now officially marked as deprecated and might be removed in the future.
PySoundFile depends on the Python packages CFFI and Numpy, and the system library libsndfile.
To install the Python dependencies, I recommend using the Anaconda Distribution of Python. Anaconda
provides the conda package manager, which will install all
dependencies using conda install cffi numpy (conda is also
independently available on pip).
You will also need to install libsndfile. On Windows, libsndfile is
included in the binary installers (see below). On OS X, homebrew can install libsndfile using
brew install libsndfile. On Linux, use your distribution's package
manager, for example sudo apt-get install libsndfile.
With CFFI, Numpy, and libsndfile installed, you can use pip to install
PySoundFile with
pip install pysoundfile or pip install pysoundfile --user if you
don't have administrator privileges. If you are running Windows you
should download the Windows installers for PySoundFile instead (which
also include libsndfile):
Data can be written to the file using write(), or read from the file
using read(). PySoundFile can open all file formats that libsndfile
supports, for example
WAV, FLAC, OGG and MAT files.
Here is an example for a program that reads a wave file and copies it into an ogg-vorbis file:
import soundfile as sf
data, samplerate = sf.read('existing_file.wav')
sf.write(data, 'new_file.ogg', samplerate=samplerate)Sound files can also be read in short, optionally overlapping 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 close() method or the context manager to
close the file explicitly:
import soundfile as sf
with sf.SoundFile('myfile.wav', 'rw') as f:
while f.tell() < len(f):
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. This is a useful idiom for opening RAW files without having to provide all the format for every file:
import soundfile as sf
format = {'format':'RAW', 'subtype':'FLOAT', 'endian':'FILE'}
data = sf.read('myfile.raw', dtype='float32', **format)
sf.write(data, 'otherfile.raw', **format)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:
from io import BytesIO
import soundfile as sf
import requests
f = BytesIO()
response = requests.get('http://www.example.com/my.flac', stream=True)
for data in response.iter_content(4096):
if data:
f.write(data)
f.seek(0)
data, samplerate = sf.read(f)In addition to audio data, there are a number of text fields in some sound files. In particular, you can set a title, a copyright notice, a software description, the artist name, a comment, a date, the album name, a license, a track number and a genre. Note however, that not all of these fields are supported for every file format.
- 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!
- 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
'x'open mode. - Added
tell()method. - Added
__repr__()method.
- Switched to