W3cubDocs

/Web APIs

BaseAudioContext: createGain() method

The createGain() method of the BaseAudioContext interface creates a GainNode, which can be used to control the overall gain (or volume) of the audio graph.

Note: The GainNode() constructor is the recommended way to create a GainNode; see Creating an AudioNode.

Syntax

createGain()

Parameters

None.

Return value

A GainNode which takes as input one or more audio sources and outputs audio whose volume has been adjusted in gain (volume) to a level specified by the node's GainNode.gain a-rate parameter.

Examples

The following example shows basic usage of an AudioContext to create a GainNode, which is then used to mute and unmute the audio when a Mute button is clicked by changing the gain property value.

The below snippet wouldn't work as is — for a complete working example, check out our Voice-change-O-matic demo (view source.)

html

<div>
  <button class="mute">Mute button</button>
</div>

const audioCtx = new AudioContext();
const gainNode = audioCtx.createGain();
const mute = document.querySelector(".mute");
let source;

if (navigator.mediaDevices.getUserMedia) {
  navigator.mediaDevices.getUserMedia(
    // constraints - only audio needed for this app
    {
      audio: true,
    },

    // Success callback
    (stream) => {
      source = audioCtx.createMediaStreamSource(stream);
    },

    // Error callback
    (err) => {
      console.error(`The following gUM error occurred: ${err}`);
    },
  );
} else {
  console.error("getUserMedia not supported on your browser!");
}

source.connect(gainNode);
gainNode.connect(audioCtx.destination);

// …

mute.onclick = () => {
  if (mute.id === "") {
    // 0 means mute. If you still hear something, make sure you haven't
    // connected your source into the output in addition to using the GainNode.
    gainNode.gain.setValueAtTime(0, audioCtx.currentTime);
    mute.id = "activated";
    mute.textContent = "Unmute";
  } else {
    gainNode.gain.setValueAtTime(1, audioCtx.currentTime);
    mute.id = "";
    mute.textContent = "Mute";
  }
};

Specifications

Specification
Web Audio API # dom-baseaudiocontext-creategain

Browser compatibility