AudioContext: createMediaStreamSource() method
The createMediaStreamSource()
method of the AudioContext
Interface is used to create a new MediaStreamAudioSourceNode
object, given a media stream (say, from a MediaDevices.getUserMedia
instance), the audio from which can then be played and manipulated.
For more details about media stream audio source nodes, check out the MediaStreamAudioSourceNode
reference page.
Syntax
js
createMediaStreamSource(stream)
Parameters
stream
-
A
MediaStream
to serve as an audio source to be fed into an audio processing graph for use and manipulation.
Return value
A new MediaStreamAudioSourceNode
object representing the audio node
whose media is obtained from the specified source stream.
Examples
In this example, we grab a media (audio + video) stream from navigator.getUserMedia
, feed the media into a <video>
element to play then mute the audio, but then also feed the audio into a MediaStreamAudioSourceNode
. Next, we feed this source audio into a low
pass BiquadFilterNode
(which effectively serves as a bass booster),
then a AudioDestinationNode
.
The range slider below the <video>
element controls the amount of
gain given to the lowpass filter — increase the value of the slider to make the audio
sound more bass heavy!
Note: You can see this example running live, or view the source.
js
const pre = document.querySelector("pre");
const video = document.querySelector("video");
const myScript = document.querySelector("script");
const range = document.querySelector("input");
// getUserMedia block - grab stream
// put it into a MediaStreamAudioSourceNode
// also output the visuals into a video element
if (navigator.mediaDevices) {
console.log("getUserMedia supported.");
navigator.mediaDevices
.getUserMedia({ audio: true, video: true })
.then((stream) => {
video.srcObject = stream;
video.onloadedmetadata = (e) => {
video.play();
video.muted = true;
};
// Create a MediaStreamAudioSourceNode
// Feed the HTMLMediaElement into it
const audioCtx = new AudioContext();
const source = audioCtx.createMediaStreamSource(stream);
// Create a biquadfilter
const biquadFilter = audioCtx.createBiquadFilter();
biquadFilter.type = "lowshelf";
biquadFilter.frequency.value = 1000;
biquadFilter.gain.value = range.value;
// connect the AudioBufferSourceNode to the gainNode
// and the gainNode to the destination, so we can play the
// music and adjust the volume using the mouse cursor
source.connect(biquadFilter);
biquadFilter.connect(audioCtx.destination);
// Get new mouse pointer coordinates when mouse is moved
// then set new gain value
range.oninput = () => {
biquadFilter.gain.value = range.value;
};
})
.catch((err) => {
console.log(`The following gUM error occurred: ${err}`);
});
} else {
console.log("getUserMedia not supported on your browser!");
}
// dump script to pre element
pre.innerHTML = myScript.innerHTML;
Note: As a consequence of calling
createMediaStreamSource()
, audio playback from the media stream will
be re-routed into the processing graph of the AudioContext
. So
playing/pausing the stream can still be done through the media element API and the
player controls.
Specifications
Specification |
---|
Web Audio API # dom-audiocontext-createmediastreamsource |
Browser compatibility
BCD tables only load in the browser