网络音频增益节点可以控制其他增益节点吗？

Question

我想创建分层 "channels"，其中 parents 增益将限制 child 的增益。

例如，我希望在 child 上播放的声音具有 0.1 音量。

var child = context.createGain();
var parent = context.createGain();
parent.gain.value = 0.1;
child.gain.value = 1.0;
child.connect(parent);

Answer 1

是的，音频增益按描述分层链接。

It multiplies the input audio signal by the (possibly time-varying) gain attribute, copying the result to the output. By default, it will take the input and pass it through to the output unchanged, which represents a constant gain change of 1.

As with other AudioParams, the gain parameter represents a mapping from time (in the coordinate system of AudioContext.currentTime) to floating-point value. Every PCM audio sample in the input is multiplied by the gain parameter's value for the specific time corresponding to that audio sample. This multiplied value represents the PCM audio sample for the output.

来自 http://www.w3.org/TR/webaudio/#GainNode

这是一个完整的例子。

<html>
<body>
<script type="text/javascript">

var AudioContext = window.AudioContext || window.webkitAudioContext;
var context = new AudioContext();

var parentGain = context.createGain();
var childGain = context.createGain();

parentGain.gain.value = 0.1;
childGain.gain.value = 1.0;

childGain.connect(parentGain);
parentGain.connect(context.destination);

var bufferSize = 4096;
var pinkNoise = (function() {
    var b0, b1, b2, b3, b4, b5, b6;
    b0 = b1 = b2 = b3 = b4 = b5 = b6 = 0.0;
    var node = context.createScriptProcessor(bufferSize, 1, 1);
    node.onaudioprocess = function(e) {
        var output = e.outputBuffer.getChannelData(0);
        for (var i = 0; i < bufferSize; i++) {
            var white = Math.random() * 2 - 1;
            b0 = 0.99886 * b0 + white * 0.0555179;
            b1 = 0.99332 * b1 + white * 0.0750759;
            b2 = 0.96900 * b2 + white * 0.1538520;
            b3 = 0.86650 * b3 + white * 0.3104856;
            b4 = 0.55000 * b4 + white * 0.5329522;
            b5 = -0.7616 * b5 - white * 0.0168980;
            output[i] = b0 + b1 + b2 + b3 + b4 + b5 + b6 + white * 0.5362;
            output[i] *= 0.11; // (roughly) compensate for gain
            b6 = white * 0.115926;
        }
    }
    return node;
})();

pinkNoise.connect(childGain);

</script>
</body>
</html>

Answer 2

是的，您可以按照您的描述串行链接增益节点。请注意，在您的示例中，这不是 "limiting" 效果 - 它是乘法的。（如果 parent.gain.value 为 2，则最终结果将是 0.2 倍的增益。）

网络音频增益节点可以控制其他增益节点吗？

Can web audio gain nodes control other gain nodes?

javascript

web-audio-api