A JavaScript Pitch Shifting Library for EarSketch with Asm.js

Abstract

A JavaScript pitch shifting library based on asm.js was developed for the EarSketch website. EarSketch is a Web Audio API-based educational website that teaches computer science principles through music technology and composition. Students write code in Python and JavaScript to manipulate and transform audio loops in a multi-track digital audio workstation paradigm. The pitchshifting library provides a cross-platform, client-side pitchshifting service to EarSketch to change the pitch of audio loop files without modifying their playback speed. It replaces a previous server-side pitch-shifting service with a noticeable increase in performance. This paper describes the implementation and performance of the library transpiled from a set of basic DSP routines written in C and converted to Asm JavaScript using emscripten.