1105019 - [Web Audio API] FM synthesis does not work correctly

Status: RESOLVED FIXED

(Core :: Web Audio, defect)

Description

[Hongchan Choi]

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_9_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/39.0.2171.65 Safari/537.36

Steps to reproduce:

var context = new AudioContext();
var mod = context.createOscillator();
var idx = context.createGain();
var car = context.createOscillator();

mod.connect(idx);
idx.connect(car.frequency);
car.connect(context.destination);

mod.frequency.value = 1000;
idx.gain.value = 1000;
car.type = 'sawtooth'; // try 'triangle', 'sawtooth' or 'square' as well
car.frequency.value = 1000;

mod.start(0.0);
car.start(0.0);
car.stop(3.0);


Actual results:

The resulting sound is a sort of distorted (pitch fluctuation, inconsistent tone).

When the modulation index is high enough (like 1000), this behavior happens consistently. Chrome and Safari do not have this issue.


Expected results:

Should produce a clean and consistent tone.

Comment 1

[Paul Adenot (:padenot)]

Fixed by bug 1106649.