How can I set a phase offset for an OscillatorNode in the Web Audio API?
audio, javascript, web-audio-api, webkit
Solution
A simple way to fake it would be to add separate delay nodes to the left and right channels, and give them user-controlled delay values. This would be my approach and will have more-or-less the same effect as a phase setting.
If you want to use `createPeriodicWave`, unfortunately you'll probably have to understand the somewhat difficult math behind it.
Basically, you'll first have to represent your waveform as a sum of sine wave "partials". All periodic waves have some representation of this form. Then, once you've found the relative magnitudes of each partial, you'll have to phase shift them separately for left and right channels by multiplying each by a complex number. You can read more details about representing periodic waves as sums of sine waves here: http://music.columbia.edu/cmc/musicandcomputers/chapter3/03_03.php
Using `createPeriodicWave` has a significant advantage over using a `BufferSourceNode`: `createPeriodicWave` waveforms will automatically avoid aliasing. It's rather difficult to avoid aliasing if you're generating the waveforms "by hand" in a buffer.
Problem
I'm trying to implement Stereo Phase as it is described here: http://www.image-line.com/support/FLHelp/html/plugins/3x%20OSC.htm "Stereo Phase (SP) - Allows you to set different phase offset for the left and right channels of the generator. The offset results in the oscillator starting at a different point on the oscillator's shape (for example, start at the highest value of the sine function instead at the zero point). Stereo phase offset adds to the richness and stereo panorama of the sound produced." I'm trying to achieve this for an OscillatorNode. My only idea is to use createPeriodicWave (https://dvcs.w3.org/hg/audio/raw-file/tip/webaudio/specification.html#dfn-createPeriodicWave) However, the description of create periodic wave from the specification is above my understanding and I have not found any examples via Google. Any help in deciphering the description of createPeriodicWave would be helpful as would any other ideas about how to achieve this effect. Thanks!