Web Audio API — frequency modulation sounds different in Chrome / Safari

Question

I'm working on a browser-based patching interface for Web Audio API synths. Frequency modulation (hooking an oscillator to the frequency of another oscillator) works as expected in Chrome. It should be a sci-fi sound like a 300Hz sin wave with the frequency wavering 30Hz.

In Safari (and Mobile Safari) it just sounds like a low rumble. It sounds like there is FM, but not the right base frequency. Is this just a browser quirk that will be ironed out in future versions? Is there a workaround now?

Here is the visual/interactive version:
html5 fm synth
http://forresto.github.com/dataflow-webaudio/

And the fiddle version, with the minimum code to demonstrate the effect:
http://jsfiddle.net/FVaWL/28/

var mod, modGain, osc;

var out = context.destination;

var startTest = function(){
    mod = context.createOscillator();
    mod.frequency.value = 8;

    modGain = context.createGain();
    modGain.gain.value = 30;

    osc = context.createOscillator();
    osc.frequency.value = 300;

    mod.connect(modGain);
    modGain.connect(osc.frequency);
    osc.connect(out);

    osc.start(0);
    mod.start(0);
};

var stopTest = function(){
    osc.stop(0);
    mod.stop(0);
    mod = modGain = osc = null;
};

cwilso cwilso · Accepted Answer · 2013-01-29T22:44:51

Safari 6's webkit has an older version of web audio. Try it on a nightly build, and it might be better - but yes, these are transient issues.

Web Audio API — frequency modulation sounds different in Chrome / Safari

2 Answers