AudioContext.createMediaStreamSource()
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
audioSourceNode = audioContext.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.
Example
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.
var pre = document.querySelector('pre');
var video = document.querySelector('video');
var myScript = document.querySelector('script');
var 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(function(stream) {
video.srcObject = stream;
video.onloadedmetadata = function(e) {
video.play();
video.muted = true;
};
// Create a MediaStreamAudioSourceNode
// Feed the HTMLMediaElement into it
var audioCtx = new AudioContext();
var source = audioCtx.createMediaStreamSource(stream);
// Create a biquadfilter
var 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 = function() {
biquadFilter.gain.value = range.value;
}
})
.catch(function(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