captureStream() on dynamically created video element

Question

I am trying to capture stream from dynamically created video element. when I get the video element and try to videoElement.captureStream() Firefox returns videoElement.captureStream is not a function but the same code works on Chrome. Problem seems like Firefox has an issue with dynamically created video element. I tried mutation observer to detect the newly added video element and access the captureStream method with no luck I am posting the code sample below (I am using adapter.js for WebRTC https://webrtc.github.io/adapter/adapter-latest.js)

(function (win) {

    var listeners = [],
        doc = win.document,
        MutationObserver = win.MutationObserver || win.WebKitMutationObserver,
        observer;

    function ready(selector, fn) {
        listeners.push({
        selector: selector,
        fn: fn
        });
        if (!observer) {
        observer = new MutationObserver(check);
        observer.observe(doc.documentElement, {
            childList: true,
            subtree: true
        });
        }
        check();
    }

    function check() {
        for (var i = 0, len = listeners.length, listener, elements; i < len; i++) {
        listener = listeners[i];
        elements = doc.querySelectorAll(listener.selector);
        for (var j = 0, jLen = elements.length, element; j < jLen; j++) {
            element = elements[j];
            if (!element.ready) {
            element.ready = true;
            listener.fn.call(element, element);
            }
        }
        }
    }

    win.ready = ready;

})(this);



ready('.jw-video',function(element){
    var stream = null;
    element.addEventListener('play',function(e){
    //with firefox here e.target.captureStream or element.captureStream returns error
    stream = e.target.captureStream();

    var mediaRecorder = new MediaRecorder(stream);
    mediaRecorder.onerror = function(error){
        console.log("media recorder error:",error);
    }
    mediaRecorder.start();
    mediaRecorder.ondataavailable = function(evt){
        console.log("mediaRecorderData");
        var blob = evt.data;

        var fileReader = new FileReader();
        var arraybuffer;
        fileReader.onload = function(){
            arraybuffer = fileReader.result;
            console.log("arraybuffer");
            console.log(arraybuffer);
            chunks.push(arraybuffer);
            sendChunks(chunks);
        };
        fileReader.readAsArrayBuffer(blob);
    }
    window.setInterval(function(){
        mediaRecorder.requestData();                            
    },3000);

    });
});

does anyone know how to access captureStream method of a newly added video element which both works on Chrome and Firefox or another approach to capture stream and convert it to arraybuffer from JWPlayer?

Answer 1

No, the problem is simply that Firefox still prefixes HTMLMediaElement#captureStream.

So you need to call video.mozCaptureStream(), and this even for inlined video elements.

console.log(`In document : 
captureStream : ${inDoc.captureStream}
mozCaptureStream : ${inDoc.mozCaptureStream}
`)

var dyn = document.createElement('video');
console.log(`Dynamic : 
captureStream : ${dyn.captureStream}
mozCaptureStream : ${dyn.mozCaptureStream}
`)

<video id="inDoc">

So in order to support both chrome and FF :

let stream = video.mozCaptureStream ? video.mozCaptureStream() : video.captureStream();