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SoundTouch Audio Processing Library

The source codes for the latest stable release are available in the git repository

About the SoundTouch library

The SoundTouch Library Copyright © Olli Parviainen 2001-2024

SoundTouch is an open-source audio processing library for changing the Tempo, Pitch and Playback Rates of audio streams or audio files. The library additionally supports estimating stable beats-per-minute rates for audio tracks.

  • Tempo (time stretch): Changes the sound to play at faster or slower tempo than originally without affecting the sound pitch.
  • Pitch (key) : Changes the sound pitch or key while keeping the original tempo (speed).
  • Playback Rate : Changes both tempo and pitch together as if a vinyl disc was played at different RPM rate.

The SoundTouch library is intended  for application developers writing sound processing tools that require tempo/pitch control functionality, or just for playing around with the sound effects.

The SoundTouch library source kit includes also an example utility SoundStretch for processing .wav audio files from command-line interface.

Access the source codes in or download the compiled executables.

More information:

SoundTouch library Features

  • Open-source implementation
  • Supports any processor and OS platform with GNU C compiler (gcc) or Visual C++: Windows, Mac OS, Linux & other *nixes, Raspberry Pi, Android, Apple iOS...
  • Support 16bit integer and 32bit floating point mono/stereo/multi-channel audio formats
  • Real-time audio processing possible:
    • input/output stream latency max. ~ 100 ms
    • Real-tome processing of CD quality stereo sound possible with a 133 Mhz Intel Pentium processor or better ;-)
  • Easy programming interface via a single C++ class
  • C++, C# and Java example applications
  • API interface modules for calling SoundTouch library routines from C#, Pascal/Delphi and Java
  • C++ implementation with MMX & SSE instruction set optimizations for x86 processors and OpenMP optimization for generic multi-core CPUs.
  • Licensed under the GNU Lesser General Public License (LGPL) v2.1. Commercial Non-LGPL license alternative available upon request.

Contact Information

Author contact information.

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Copyright © Olli Parviainen