在Javascript中控制音频平衡（L / R）

Question

I want to control the audio balance when I use this code

var oscillator = audioCtx.createOscillator();

oscillator.type = 'square';
oscillator.frequency.value = frequency; // value in hertz
oscillator.connect(audioCtx.destination);
oscillator.start();
setTimeout(function(){oscillator.stop();}, duration);   

and also when I play a local mp3 file. How can I do this?

Answer 1

Add a StereoPannerNode to the chain using createStereoPanner :

var oscillator = audioCtx.createOscillator();
var panner = audioCtx.createStereoPanner();

oscillator.type = 'square';
oscillator.frequency.value = frequency;  // value in hertz
oscillator.connect(panner);              // connect audio source to panner
panner.connect(audioCtx.destination);    // connect panner to output
oscillator.start();

Now you can control the L/R using:

panner.pan.value = someValue;   // value in the range -1 (L) to 1 (R)

Functional example:

 var audioCtx = new (AudioContext || webkitAudioContext)(); var oscillator = audioCtx.createOscillator(); var panner = audioCtx.createStereoPanner(); oscillator.type = 'square'; oscillator.frequency.value = 440; // value in hertz oscillator.connect(panner); panner.connect(audioCtx.destination); oscillator.start(); document.querySelector("input").oninput = function() { panner.pan.value = +this.value; }; setInterval(function() { oscillator.frequency.value = Math.round(Math.random() * 10) * 400 + 200; }, 100); 

 <label>L <input type=range min=-1 max=1 value=0 step=0.01> R</label>