The CanvasCaptureMediaStreamTrack method requestFrame() requests that a frame be captured from the canvas and sent to the stream. Applications that need to carefully control the timing of rendering and frame capture can use requestFrame() to directly specify when it's time to capture a frame.

To prevent automatic capture of frames, so that frames are only captured when requestFrame() is called, specify a value of 0 for the captureStream() method when creating the stream.



Return value


Usage notes

There is currently an issue flagged in the specification pointing out that at this time, no exceptions are being thrown if the canvas isn't origin-clean. This may change in the future, so it would be wise to plan ahead and watch for exceptions such as SecurityError (although the specific error that might be thrown is not mentioned in the spec, this is a likely candidate).


// Find the canvas element to capture
var canvasElt = document.getElementsByTagName("canvas")[0];

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

// Send the current state of the canvas as a frame to the stream


Specification Status Comment
Media Capture from DOM Elements
The definition of 'CanvasCaptureMediaStream.requestFrame()' in that specification.
Working Draft Initial definition

Browser compatibility

ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
Chrome Full support 51Edge Full support ≤79Firefox Full support 41
Full support 41
Disabled From version 41: this feature is behind the canvas.capturestream.enabled preference (needs to be set to true). To change preferences in Firefox, visit about:config.
IE No support NoOpera No support NoSafari No support NoWebView Android Full support 51Chrome Android Full support 51Firefox Android ? Opera Android No support NoSafari iOS No support NoSamsung Internet Android Full support 5.0


Full support
Full support
No support
No support
Compatibility unknown
Compatibility unknown
Experimental. Expect behavior to change in the future.
Experimental. Expect behavior to change in the future.
User must explicitly enable this feature.
User must explicitly enable this feature.

See also