tonegenerator

ToneGenerator for node.js

This thing generates raw PCM data, specified by a frequency and length in seconds.

var tone = require("tonegenerator");
var A440 = tone(440, 20); // get PCM data for a 440hz A, 20 seconds.

The data is returned as a normal array, so you can do operations on it. Before writing to a file, you need to convert it to a buffer:

var tone = require("tonegenerator");
var header = require("waveheader"); // https://www.npmjs.org/package/waveheader
var fs = require("fs");

// An A-major chord
var tone1 = tone(440, 2);
var tone2 = tone(554.37, 2);
var tone3 = tone(659.26, 2);

// "playing" one tone at the time
// note that at this time, our sound is just an array 
// of gain values. By appending the raw PCM data for one after another,
// we can play them in a sequence
var res = [].concat(tone1);
res = res.concat(tone2);
res = res.concat(tone3);

// By adding values of the tones for each sample,
// we play them simultaneously, as a chord
for(var i = 0; i < tone1.length; i++) {
  res.push(tone1[i] + tone2[i] + tone3[i]);
}

// write to file (note conversion to buffer!)
var writer = new fs.createWriteStream("A-major.wav");
writer.write(header( 44100 * 8 )); // 44100 Hz * 8 seconds
writer.write(new Buffer(res));
writer.end();