How to process audio from the user's microphone
Accessing the user's camera and microphone is possible on the web platform with the Media Capture and Streams API. The getUserMedia()
method prompts the user to access a camera and/or microphone to capture as a media stream. This stream can then be processed in a separate Web Audio thread with an AudioWorklet that provides very low latency audio processing.
The example below shows how you can process audio from the user's microphone in a performant way.
let stream;
startMicrophoneButton.addEventListener("click", async () => {
// Prompt the user to use their microphone.
stream = await navigator.mediaDevices.getUserMedia({
audio: true,
});
const context = new AudioContext();
const source = context.createMediaStreamSource(stream);
// Load and execute the module script.
await context.audioWorklet.addModule("processor.js");
// Create an AudioWorkletNode. The name of the processor is the
// one passed to registerProcessor() in the module script.
const processor = new AudioWorkletNode(context, "processor");
source.connect(processor).connect(context.destination);
log("Your microphone audio is being used.");
});
stopMicrophoneButton.addEventListener("click", () => {
// Stop the stream.
stream.getTracks().forEach(track => track.stop());
log("Your microphone audio is not used anymore.");
});
// processor.js
// This file is evaluated in the audio rendering thread
// upon context.audioWorklet.addModule() call.
class Processor extends AudioWorkletProcessor {
process([input], [output]) {
// Copy inputs to outputs.
output[0].set(input[0]);
return true;
}
}
registerProcessor("processor", Processor);
Browser support #
MediaDevices.getUserMedia() #
Browser support
- Chrome 53, Supported 53
- Firefox 36, Supported 36
- Edge 12, Supported 12
- Safari 11, Supported 11
Web Audio #
Browser support
- Chrome 35, Supported 35
- Firefox 25, Supported 25
- Edge 12, Supported 12
- Safari 14.1, Supported 14.1
AudioWorklet #
Browser support
- Chrome 66, Supported 66
- Firefox 76, Supported 76
- Edge 79, Supported 79
- Safari 14.1, Supported 14.1
Further reading #
Demo #
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8" />
<meta name="viewport" content="width=device-width, initial-scale=1" />
<link
rel="icon"
href="data:image/svg+xml,<svg xmlns=%22http://www.w3.org/2000/svg%22 viewBox=%220 0 100 100%22><text y=%22.9em%22 font-size=%2290%22>🎙️</text></svg>"
/>
<title>How to process audio from the user's microphone</title>
</head>
<body>
<h1>How to process audio from the user's microphone</h1>
<button id="startMicrophoneButton">Start using microphone</button>
<button id="stopMicrophoneButton" disabled>Stop using microphone</button>
<pre id="logs"></pre>
</body>
</html>
// This file is evaluated in the audio rendering thread
// upon context.audioWorklet.addModule() call.
class WorkletProcessor extends AudioWorkletProcessor {
process([input], [output]) {
// Copy inputs to outputs.
output[0].set(input[0]);
return true;
}
}
registerProcessor("processor", WorkletProcessor);
const startMicrophoneButton = document.querySelector('#startMicrophoneButton');
const stopMicrophoneButton = document.querySelector('#stopMicrophoneButton');
let stream;
startMicrophoneButton.addEventListener("click", async () => {
// Prompt the user to use their microphone.
stream = await navigator.mediaDevices.getUserMedia({
audio: true,
});
const context = new AudioContext();
const source = context.createMediaStreamSource(stream);
// Load and execute the module script.
await context.audioWorklet.addModule("processor.js");
// Create an AudioWorkletNode. The name of the processor is the
// one passed to registerProcessor() in the module script.
const processor = new AudioWorkletNode(context, "processor");
source.connect(processor).connect(context.destination);
stopMicrophoneButton.disabled = false;
log("Your microphone audio is being used.");
});
stopMicrophoneButton.addEventListener("click", () => {
// Stop the stream.
stream.getTracks().forEach(track => track.stop());
log("Your microphone audio is not used anymore.");
});
:root {
color-scheme: dark light;
}
html {
box-sizing: border-box;
}
*,
*:before,
*:after {
box-sizing: inherit;
}
body {
margin: 1rem;
font-family: system-ui, sans-serif;
}
button {
display: block;
margin-bottom: 4px;
}
pre {
color: red;
white-space: pre-line;
}