HTTPLiveSource.js

/*
 * A HTTP Source for Aurora.JS (https://github.com/audiocogs/aurora.js) allowing real-time decoding and playing.
 * Use fetch & Streams API in order to process the response in real-time.
 *
 * Example :
 *
 * var player = new AV.Player(new AV.Asset(new HTTPLiveSource('http://example.com/live.aac')))
 * player.play();
 *
 */

var HTTPLiveSource = (function(){
	var fetchSupport = (typeof fetch !== 'undefined');
	var writableStreamSupport = (typeof WritableStream !== 'undefined');
	var readableStreamSupport = (typeof ReadableStream !== 'undefined');

	function write(buf) {
		var buffer = new AV.Buffer(buf);
		this.length = (this.offset += buffer.length);
		this.emit('data', buffer);
	}
	function end() {
		if (this.controller)
		{
			this.emit('end');
			this.controller = null;
		}
	}
	function abort(err) {
		if (this.controller)
		{
			this.emit('error', err);
			this.emit('end');
			this.controller = null;
		}
	}

	function HTTPLiveSource(url) {
		AV.EventEmitter.call(this);
		if (!fetchSupport || !(writableStreamSupport || readableStreamSupport)) {
			return this.emit('error', 'This browser does not have Fetch and Steams API support.');
		}
		this.url = url;
	}

	HTTPLiveSource.prototype = AV.EventEmitter.prototype;

	if (writableStreamSupport)
		HTTPLiveSource.prototype.start = function() {
			if (this.controller)
				this.pause();
			var stream = new WritableStream({
				write: write.bind(this),
				close: end.bind(this),
				abort: abort.bind(this)
			}, new ByteLengthQueuingStrategy({ highWaterMark: 8192 }));
			this.controller = new AbortController();
			return fetch(this.url, { signal: this.controller.signal })
				.then(function(res) {
					return res.body.pipeTo(stream);
				});
		};
	else
		HTTPLiveSource.prototype.start = function() {
			if (this.controller)
				this.pause();
			this.controller = new AbortController();
			var source = this;
			return fetch(this.url, { signal: this.controller.signal })
				.then(function(res) {
					return res.body.getReader();
				})
				.then(function(reader) {
					var _abort = abort.bind(source);
					function consume() {
						reader.read()
							.then(function(res) {
								if (res.done)
									return end.call(source);
								write.call(source, res.value);
								consume();
							})
							.catch(_abort);
					}
					consume();
				});
		};

	HTTPLiveSource.prototype.pause = function pause() {
		var controller = this.controller;
		this.controller = null;
		this.emit('end');
		controller.abort();
	};

	HTTPLiveSource.prototype.reset = HTTPLiveSource.prototype.pause;

	return HTTPLiveSource;
})();