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(e.target.result));
logger.log('appending chunk:' + idx);
if (idx == NUM_CHUNKS - 1) {
video.webkitSourceEndOfStream(HTMLMediaElement.EOS_NO_ERROR);
}
};
})(i);
reader.readAsArrayBuffer(chunk);
}
}, 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
.