Web Audio API 将单声道拆分为立体声

Question

假设我有一个连接到目标节点的源节点。 即使音频是单声道的，我也希望能够独立控制每只耳朵的音量，就像我拥有带有分离器和合并节点的立体声音频时一样。

已经尝试在单声道源节点上使用拆分器和合并节点，但是右声道出来是空的。

立体声示例：

var audioCtx = new AudioContext();
var source = audioCtx.createMediaElementSource(myAudio);
var gainNodeL = audioCtx.createGain();
var gainNodeR = audioCtx.createGain();
var splitter = audioCtx.createChannelSplitter(2);
var merger = audioCtx.createChannelMerger(2);

source.connect(splitter);
splitter.connect(gainNodeL, 0);
splitter.connect(gainNodeR, 1);

gainNodeL.connect(merger, 0, 0);
gainNodeR.connect(merger, 0, 1);

merger.connect(audioCtx.createMediaStreamDestination());

当我对单声道音频执行此操作时，右声道会空出来。

Answer 1

如果信号只是单声道（或者换句话说，它的 channelCount 为 1），则不需要 ChannelSplitterNode。我稍微修改了这个例子。它现在可以拆分振荡器的单声道信号。

var audioCtx = new AudioContext();
var oscillator = audioCtx.createOscillator();
var gainNodeL = audioCtx.createGain();
var gainNodeR = audioCtx.createGain();
var merger = audioCtx.createChannelMerger(2);

oscillator.connect(gainNodeL);
oscillator.connect(gainNodeR);

gainNodeL.connect(merger, 0, 0);
gainNodeR.connect(merger, 0, 1);

merger.connect(audioCtx.destination);

oscillator.start();

function left () {
    gainNodeL.gain.value = 1;
    gainNodeR.gain.value = 0;
}

function right () {
    gainNodeL.gain.value = 0;
    gainNodeR.gain.value = 1;
}

function center () {
    gainNodeL.gain.value = 1;
    gainNodeR.gain.value = 1;
}