html - Generating sound on the fly with javascript/html5

Question

Is it possible to generate a constant sound stream with javascript/html5? For example, to generate a perpetual sine wave, I would have a callback function, that would be called whenever the output buffer is about to become empty:

function getSampleAt(timestep)
{
    return Math.sin(timestep);
}

(The idea is to use this to make an interactive synth. I don't know in advance how long a key will be pressed, so I can't use a fixed length buffer)

Answer 1

You can use the Web Audio API in most browsers now (excepting IE and Opera Mini).

Try out this code:

// one context per document
var context = new (window.AudioContext || window.webkitAudioContext)();
var osc = context.createOscillator(); // instantiate an oscillator
osc.type = 'sine'; // this is the default - also square, sawtooth, triangle
osc.frequency.value = 440; // Hz
osc.connect(context.destination); // connect it to the destination
osc.start(); // start the oscillator
osc.stop(context.currentTime + 2); // stop 2 seconds after the current time