timestretch

Yet another library to timestretch audio on the browser.

The focus of this implementaion is to make the code easy to understand. There will be examples of how to:

• Pitchshift an audio buffer
• Perform pitchshifting using a webworker
• Realtime pitchshifting of an audio source

This is not the best implementation if you're looking for sound quality and/or performance (see FAQ).

This is work in progress

(FA)Q

Are other implementations available?

Yes, some of them:

• https://github.com/sebpiq/paulstretch.js
• https://github.com/echo66/OLA-TS.js
• https://github.com/echo66/PhaseVocoderJS
• https://github.com/Infinity/Kali
• https://github.com/0xfe/vexwarp
• https://github.com/mikolalysenko/pitch-shift
• https://github.com/GTCMT/pitchshiftjs

And there are probably more...

Which one should I use?

I don't know by experiencie, but @echo66 projects looks promising.

Then, why?

Because I want to learn.

Resources

• Time Stretching And Pitch Shifting of Audio Signals – An Overview: http://blogs.zynaptiq.com/bernsee/time-pitch-overview/
• Time and pitch scaling in audio processing: http://www.surina.net/article/time-and-pitch-scaling.html
• Basic Time Stretching (that sounds remarkably well): https://github.com/martijnvogten/timestretch/wiki/Basic-Time-Stretching-(that-sounds-remarkably-well)
• Time Stretching & Pitch Shifting with the Web Audio API. Where are we at? (pdf): https://github.com/echo66/time-stretch-wac-article/blob/master/ts-ps-wac.pdf
• Free small FFT in multiple languages: https://www.nayuki.io/page/free-small-fft-in-multiple-languages
• FFT in javascript: https://thebreakfastpost.com/2015/10/18/ffts-in-javascript/
• http://code.almeros.com/experimenting-with-firefox-audio-api#.V-LzSJOLTMU

License

MIT License