Stream video using the MediaSource API

The MediaSource API extends the HTMLMediaElement to allow JavaScript to generate media streams for playback. Allowing JavaScript to generate streams facilitates a variety of use cases like adaptive streaming and time shifting live streams.

Here is a quick demo and example usage of API:

const NUM_CHUNKS = 5;

var video = document.querySelector('video');
video.src = video.webkitMediaSourceURL;

video.addEventListener('webkitsourceopen', function(e) {
    var chunkSize = Math.ceil(file.size / NUM_CHUNKS);

    // Slice the video into NUM_CHUNKS and append each to the media element.
    for (var i = 0; i < NUM_CHUNKS; ++i) {
    var startByte = chunkSize * i;

    // file is a video file.
    var chunk = file.slice(startByte, startByte + chunkSize);

    var reader = new FileReader();
    reader.onload = (function(idx) {
        return function(e) {
        video.webkitSourceAppend(new Uint8Array(;
        logger.log('appending chunk:' + idx);
        if (idx == NUM_CHUNKS - 1) {

}, false);


The example splits a .webm video into 5 chunks using the File APIs. The entire movie is then 'streamed' to a <video> tag by appending each chunk to the element using the MediaSource API.

If you're interested in learning more about the API, see the specification.

Support: Currently, the MediaSource API is only available in Chrome Dev Channel 17+ with the --enable-media-source flag set or enabled via about:flags.