HTMLCanvasElement.captureStream()

The HTMLCanvasElement captureStream() method returns a MediaStream which includes a CanvasCaptureMediaStreamTrack containing a real-time video capture of the canvas's contents.

Syntax

MediaStream = canvas.captureStream(frameRate);

Parameters

frameRate Optional

A double-precision floating-point value that indicates the rate of capture of each frame. If not set, a new frame will be captured each time the canvas changes; if set to 0, frames will not be captured automatically; instead, they will only be captured when the returned track's requestFrame() method is called.

Return value

A reference to a MediaStream object, which has a single CanvasCaptureMediaStreamTrack in it.

Exceptions

NotSupportedError DOMException

Thrown if the value of frameRate is negative.

Example

// Find the canvas element to capture
var canvasElt = document.querySelector('canvas');

// Get the stream
var stream = canvasElt.captureStream(25); // 25 FPS

// Do things to the stream
// E.g. Send it to another computer using an RTCPeerConnection
//      pc is an RTCPeerConnection created elsewhere
pc.addStream(stream);

Specifications

Specification
Media Capture from DOM Elements
# dom-htmlcanvaselement-capturestream

Browser compatibility

Report problems with this compatibility data on GitHub
desktopmobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariWebView AndroidChrome AndroidFirefox for AndroidOpera AndroidSafari on iOSSamsung Internet
captureStream
Experimental
Full support
Full support
No support
No support
Experimental. Expect behavior to change in the future.

See also