在Web Audio API中，有没有办法设置最大音量？

Question

I know you can boost or reduce volume with gain. I was wondering if there was a way (perhaps via a node) to cap the maximum volume of the output - not reducing any audio below that max value. It is acceptable if there is distortion for audio that gets capped like this.

Answer 1

An alternative that might be simpler is to use a WaveShaperNode . I think a curve equal to [-1, 0, 1] will do what you want, clamping values to +/-1. If you don't oversample, there won't be any additional delay.

Note that I'm pretty sure all browsers implement this kind of clamping before sending audio to the speakers.

Answer 2

This is not possible with any of the built-in AudioNodes. But it can be achieved with a custom AudioWorklet. I recently published a package which does exactly that. It's called limiter-audio-worklet .

It exports two functions:

import { addLimiterAudioWorkletModule, createLimiterAudioWorkletNode } from 'limiter-audio-worklet';

The first function can be used to add the AudioWorklet to a particular AudioContext .

await addLimiterAudioWorkletModule((url) => {
    audioContext.audioWorklet.addModule(url);
});

Once that is done the actual AudioWorkletNode can be created like this:

const limiterAudioWorkletNode = createLimiterAudioWorkletNode(
    AudioWorkletNode,
    audioContext,
    { attack: 0 }
);

If you set the attack two zero you get the desired effect. Everything above +1/-1 gets clamped. If you increase the attack it will transition smoother using a look ahead. This will introduce a small delay (of the same size) but sounds much nicer.

Of course it's also necessary to connect the previously created limiterAudioWorkletNode close to the end of your audio graph.

yourLastAudioNode
    .connect(limiterAudioWorkletNode)
    .connect(audioContext.destination);