A real-time audio time-scale modification library

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AudioTSM is a python library for real-time audio time-scale modification procedures, i.e. algorithms that change the speed of an audio signal without changing its pitch.

Source code repository and issue tracker:
Python Package Index:
MIT – see the file LICENSE for details.


Audiotsm should work with python 2.7 and python 3.4+.

You can install the latest version of audiotsm with pip:

pip install audiotsm

You may also need to install the sounddevice library in order to run the examples or to use a StreamWriter:

pip install sounddevice

Basic usage

The audiotsm package implements several time-scale modification procedures:

  • OLA (Overlap-Add), which should only be used for percussive audio signals;
  • WSOLA (Waveform Similarity-based Overlap-Add), an amelioration of the OLA procedure which should give good results on most inputs.

Below is a basic example showing how to reduce the speed of a wav file by half using the WSOLA procedure:

from audiotsm import wsola
from audiotsm.io.wav import WavReader, WavWriter

with WavReader(input_filename) as reader:
    with WavWriter(output_filename, reader.channels, reader.samplerate) as writer:
        tsm = wsola(reader.channels, speed=0.5)
        tsm.run(reader, writer)


If you are interested in time-scale modification procedures, I highly recommend reading A Review of Time-Scale Modification of Music Signals by Jonathan Driedger and Meinard Müller.

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