pitch-shift

A variable speed pitch shifter written in JavaScript.

Here is a demo you can try in your browser!

Example

Here is a simplified psuedo-example:

//Create a pitch shifting object
var shifter = require("pitch-shift")(
  function onData(frame) {
    //Play / write out frame.  Called whenver data is ready
  },
  function onTune(t, pitch) {
  
    console.log("Got pitch ", pitch, " at time ", t)
    
    //This is the amount to scale the sample by
    return 1.0
  })
  

//Feed some data to the shifter
shifter(new Float32Array([1, 1, 0, 1, 0, 0, 0 /* ... etc */ ]))

For a more complete working example, check out test/test.js or example/index.js

Install

npm install pitch-shift

require("pitch-shift")(onData, onTune, options)

Creates a pitch shifting function

• onData(frame) Called when a pitch shifted frame is ready.

• onTune(t, pitch) Called when a frame of audio needs to be processed.

• options An object full of options to pass to the pitch shifter

  • frameSize size of frame to process (default 2048)
  • hopSize the distance between frames in samples. Must divide frame size. (default frameSize/4)
  • dataSize maximal allowable size of a data frame (default frame_size)
  • sampleRate Conversion factor from samples to seconds. (default 44100)
  • analysiWindow analysis window. must be a typed array with length equl to frame size (defaults to Hann window)
  • synthesisWindow synthesis window. must be a typed array with length equal to frame size (defaults to Hann window)
  • threshold peak detection threshold. Set to 1.0 to always take maximum, otherwise set lower to detect half tones. (default 0.9)
  • minPeriod Minimal resolvable period. (default sampleRate/400)

Returns A function that you call with a frame of data.

Credits

(c) 2013 Mikola Lysenko. MIT License

Gettysburg adress reading by Britton Rea. Recording obtained from the Internet archive. http://archive.org/details/GettysburgAddress