Rubber Band Library

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Why choose Rubber Band Library?


Rubber Band Library is a professionally engineered, reliable and efficient native library that solves many real-world problems around time-stretching and pitch-shifting. It is designed to work reliably in many difficult situations. It is well-documented and easy to build and integrate.

Sound quality

Rubber Band provides two processing engines, a faster engine and a finer-quality one (introduced in version 3.0). The faster engine already avoids most of the grainy and gritty artifacts that many other time-stretching and pitch-shifting libraries suffer from, providing punchy percussion and smooth stretches with large ratios. The finer engine builds on this, to provide near-hi-fi quality adaptation even of acoustic ensembles and complete mixes.

No time-stretcher is entirely transparent and Rubber Band has limits, but it is designed to be appropriate for musical use in many contexts, and offers a number of adjustable controls for less common situations.

In addition to the audio examples here, you can put Rubber Band to the test yourself by downloading our own app which uses the library.


High quality time-stretching and pitch-shifting are quite CPU-intensive operations, but Rubber Band is still fast enough to run in real-time on any mobile device from iPhone 4S onwards and takes only a small fraction of the processing power of current devices. Rubber Band has predictable performance characteristics and can be used for very substantial stretches and pitch shifts — up to three octaves is entirely practical.

Rubber Band's real-time mode is a true lock-free streaming mode, in which time and pitch scaling can both be freely adjusted during use. Rubber Band also has an offline mode with sample-exact stretching and multi-processor support.

Rubber Band performs better than many competing commercial libraries in several of these characteristics.


"Fantastic library that can elevate any audio player! Integration process was made easy due to the genuinely helpful support from the author" — Ziad Halabi, BackTrackit

"The audio quality [of Rubber Band] is great... it handles audio transients well and does a great job in preserving audio quality" — Patrick Vlaskovits, Superpowered (in a document promoting their own time stretcher library!)

"Thank you, this is truly amazing – you guys are killing it! I really love what you are doing" — Robert Avellar, SoundWare

"I consider Rubber Band to be one of the true gems of open source audio software"Fons Adriaensen

Rubber Band has been licensed commercially by companies of all sizes and independent developers around the world, across more than 20 countries, for use in their own creative applications. Some of the world's largest companies and many of the world's most talented individuals have evaluated and chosen to use our work and have been delighted in the results.


Rubber Band has been developed and refined throughout the past 15 years, retaining code compatibility while delivering reliability updates and substantial new features. Recent updates have introduced a dramatically high-quality new processing mode and a faster version of it that produces excellent results for vocal processing. Browse our news feed for more details.

Licensing and Support

Rubber Band has super-sensible commercial licensing, transparent and affordable even for smaller developers. Rubber Band is also published under the GNU General Public License for use in GPL applications.

If you have any problems integrating Rubber Band, we can offer commercial support — please contact us to ask.