gearmonkey / audioread

cross-library (GStreamer + Core Audio + MAD + FFmpeg) audio decoding for Python

audioread

Decode audio files using whichever backend is available. The library currently supports:

• Gstreamer via gst-python.
• Core Audio on Mac OS X via ctypes. (PyObjC not required.)
• MAD via the pymad bindings.
• FFmpeg via its command-line interface.
• The standard library wave and aifc modules (for WAV and AIFF files).

Use the library like so:

with audioread.audio_open(filename) as f:
    print f.channels, f.samplerate, f.duration
    for buf in f:
        do_something(buf)

Buffers in the file can be accessed by iterating over the object returned from audio_open. Each buffer is a buffer or str object containing raw 16-bit little-endian signed integer PCM data. (Currently, these PCM format parameters are not configurable, but this could be added to most of the backends.)

Additional values are available as fields on the audio file object:

• channels is the number of audio channels (an integer).
• samplerate is given in Hz (an integer).
• duration is the length of the audio in seconds (a float).

The audio_open function transparently selects a backend that can read the file. (Each backend is implemented in a module inside the audioread package.) If no backends succeed in opening the file, a DecodeError exception is raised. This exception is only used when the file type is unsupported by the backends; if the file doesn't exist, a standard IOError will be raised.

Future Work

Possible additional backends:

• PyOgg?
• Other command-line tools?

Example

The included decode.py script demonstrates using this package to convert compressed audio files to WAV files.

Version History

0.5

Fix crash when FFmpeg fails to report a duration. Fix a hang when FFmpeg fills up its stderr output buffer. Add a timeout to ffmpeg tool execution (currently 10 seconds for each 4096-byte read); a ReadTimeoutError exception is raised if the tool times out.

0.4

Fix channel count detection for FFmpeg backend.

0.3

Fix a problem with the Gstreamer backend where audio files could be left open even after the GstAudioFile was "closed".

0.2

Fix a hang in the GStreamer backend that occurs occasionally on some platforms.

0.1

Initial release.

Et Cetera

audioread is by Adrian Sampson. It is made available under the MIT license. An alternative to this module is decoder.py.