rx-player
Version:
Canal+ HTML5 Video Player
54 lines (53 loc) • 1.74 kB
JavaScript
;
/**
* Copyright 2015 CANAL+ Group
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
Object.defineProperty(exports, "__esModule", { value: true });
/**
* Tweaked implementation of an exponential weighted Moving Average.
* @class EWMA
*/
var EWMA = /** @class */ (function () {
/**
* @param {number} halfLife
*/
function EWMA(halfLife) {
// (half-life = log(1/2) / log(Decay Factor)
this._alpha = Math.exp(Math.log(0.5) / halfLife);
this._lastEstimate = 0;
this._totalWeight = 0;
}
/**
* @param {number} weight
* @param {number} value
*/
EWMA.prototype.addSample = function (weight, value) {
var adjAlpha = Math.pow(this._alpha, weight);
var newEstimate = value * (1 - adjAlpha) + adjAlpha * this._lastEstimate;
if (!isNaN(newEstimate)) {
this._lastEstimate = newEstimate;
this._totalWeight += weight;
}
};
/**
* @returns {number} value
*/
EWMA.prototype.getEstimate = function () {
var zeroFactor = 1 - Math.pow(this._alpha, this._totalWeight);
return this._lastEstimate / zeroFactor;
};
return EWMA;
}());
exports.default = EWMA;