pico.js

What is?

Pico.js is a JavaScript library for real-time audio processing that runs a browser and node.js.

Support

Tutorial

1. Make an object implemented a function process(L, R)

   Arguments L and R are instanceof Float32Array

2. Start processing: pico.play(gen);

   Write signal into L and R in gen.process(L, R)

3. Stop processing: pico.pause();

   The silence come

ex.01 Pause Play

// Generate whitenoise
var noise = {
    process: function(L, R) {
        for (var i = 0; i < L.length; i++) {
            L[i] = R[i] = Math.random() * 0.25;
        }
    }
};
pico.play(noise);

Others features

1. Change the samplerate

   pico.setup({samplerate:24000})

   You can choose some one [8000, 11025, 12000, 16000, 22050, 24000, 32000, 44100, 48000]

2. Flash fallback

   Put in the 'pico.swf' to in the same folder as 'pico.js'

3. node.js support

   You can install with npm.

   $ npm install node-pico

   See: repository demo/node-demo.js

ex.02 Pause Play

// Generate sinetone
function sinetone(freq) {
    var phase = 0,
        phaseStep = freq / pico.samplerate;
    return {
        process: function(L, R) {
            for (var i = 0; i < L.length; i++) {
                L[i] = R[i] = Math.sin(6.28318 * phase) * 0.25;
                phase += phaseStep;
            }
        }
    };
}
pico.play(sinetone(880));

Methods

1. pico.play(gen)

   Start processing

2. pico.pause()

   Stop processing

3. pico.setup(opts)

   Setup samplerate and cellsize

4. pico.bind(PlayerClass, opts)

   Use another PlayerClass (for example via Flash)

Properties

• pico.isPlaying

  Return true if processing

• pico.env

  Return environment (webkit, moz, flash, nop=no operation)

• pico.samplerate

  Return samplerate

• pico.channels

  Return channels (always return 2)

• pico.cellsize

  Return length of samples to be processed

ex.03 Pause Play

// Generate music from one-liner function
window.f1 = function(t) {
    return Math.sin(t*(0.001+Math.sin(t>>10)))*64;
};
window.f2 = function(t) {
    return (t>>9)&((t<<5)|(Math.sin(t*1.4142)*3000))+(t>>3);
};

function oneliner() {
    var t = 0, dt = 8000 / pico.samplerate;
    var dlyL = new pico.DelayNode({time:225, feedback:0.8});
    var dlyR = new pico.DelayNode({time:225, feedback:0.8});
    return {
        process: function(L, R) {
            for (var i = 0; i < L.length; i++) {
                L[i] = (window.f1(t|0) % 256) / 512;
                R[i] = (window.f2(t|0) % 256) / 512;
                t += dt;
            }
            dlyL.process(L, true);
            dlyR.process(R, true);
        }
    };
}
pico.play(oneliner());

Source

• pico.js (minified) / source maps
• pico.dev.js (uncompressed)
• pico.swf (Flash fallback)
• Hosted on GitHub

License

• MIT

Tweet

ex.04 Pause Play

// Demo song of MML and FM synthesis
// TO MAKE THE END OF BATTLE/Ys2
//     Copyright©　Nihon Falcom Corporation
// 
// Original MML Data
// http://d.hatena.ne.jp/mosshm/20071013/p1

pico.play(demo());