PySoundFile 0.7.0

An audio library based on libsndfile, CFFI and NumPy

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.

PySoundFile is BSD licensed (BSD 3-Clause License).

(c) 2013, Bastian Bechtold

Breaking Changes

PySoundFile 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.

Installation

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 3. This will come with all dependencies pre-installed. To install the dependencies manually, you can use the conda package manager, which will install all dependencies using conda install cffi numpy (conda is also available independently of Anaconda with pip install conda; conda init).

With CFFI and NumPy installed, you can use pip install pysoundfile to download and install the latest release of PySoundFile. 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.

Read/Write Functions

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)

Block Processing

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)]

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 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.

RAW Files

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)

Virtual IO

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)

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!

• Switched to float64 as 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.

2015-04-xx 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 to import soundfile.

• Installation through pip wheels that contain the necessary libraries for OS X and Windows.

• Removed exclusive_creation argument to write.

• Added truncate() method.