@l5i/dashjs/build/es5/src/streaming/utils/baseUrlResolution/DVBSelector.js

A reference client implementation for the playback of MPEG DASH via Javascript and compliant browsers.

/**
 * The copyright in this software is being made available under the BSD License,
 * included below. This software may be subject to other third party and contributor
 * rights, including patent rights, and no such rights are granted under this license.
 *
 * Copyright (c) 2013, Dash Industry Forum.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *  * Redistributions of source code must retain the above copyright notice, this
 *  list of conditions and the following disclaimer.
 *  * Redistributions in binary form must reproduce the above copyright notice,
 *  this list of conditions and the following disclaimer in the documentation and/or
 *  other materials provided with the distribution.
 *  * Neither the name of Dash Industry Forum nor the names of its
 *  contributors may be used to endorse or promote products derived from this software
 *  without specific prior written permission.
 *
 *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS AS IS AND ANY
 *  EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 *  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 *  IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 *  INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 *  NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 *  PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 *  WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 *  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 *  POSSIBILITY OF SUCH DAMAGE.
 */'use strict';Object.defineProperty(exports,'__esModule',{value:true});function _interopRequireDefault(obj){return obj && obj.__esModule?obj:{'default':obj};}var _coreFactoryMaker=require('../../../core/FactoryMaker');var _coreFactoryMaker2=_interopRequireDefault(_coreFactoryMaker);function DVBSelector(config){config = config || {};var instance=undefined;var blacklistController=config.blacklistController;function getNonBlacklistedBaseUrls(urls){var removedPriorities=[];var samePrioritiesFilter=function samePrioritiesFilter(el){if(removedPriorities.length){if(el.dvb_priority && removedPriorities.indexOf(el.dvb_priority) !== -1){return false;}}return true;};var serviceLocationFilter=function serviceLocationFilter(baseUrl){if(blacklistController.contains(baseUrl.serviceLocation)){ // whenever a BaseURL is removed from the available list of
// BaseURLs, any other BaseURL with the same @priority
// value as the BaseURL being removed shall also be removed
if(baseUrl.dvb_priority){removedPriorities.push(baseUrl.dvb_priority);} // all URLs in the list which have a @serviceLocation
// attribute matching an entry in the blacklist shall be
// removed from the available list of BaseURLs
return false;}return true;};return urls.filter(serviceLocationFilter).filter(samePrioritiesFilter);}function selectByWeight(availableUrls){var prioritySorter=function prioritySorter(a,b){var diff=a.dvb_priority - b.dvb_priority;return isNaN(diff)?0:diff;};var topPriorityFilter=function topPriorityFilter(baseUrl,idx,arr){return !idx || arr[0].dvb_priority && baseUrl.dvb_priority && arr[0].dvb_priority === baseUrl.dvb_priority;};var totalWeight=0;var cumulWeights=[];var idx=0;var rn=undefined,urls=undefined; // It shall begin by taking the set of resolved BaseURLs present or inherited at the current
// position in the MPD, resolved and filtered as described in 10.8.2.1, that have the lowest
// @priority attribute value.
urls = availableUrls.sort(prioritySorter).filter(topPriorityFilter);if(urls.length){if(urls.length > 1){ // If there is more than one BaseURL with this lowest @priority attribute value then the Player
// shall select one of them at random such that the probability of each BaseURL being chosen
// is proportional to the value of its @weight attribute. The method described in RFC 2782
// [26] or picking from a number of weighted entries is suitable for this, but there may be other
// algorithms which achieve the same effect.
// add all the weights together, storing the accumulated weight per entry
urls.forEach(function(baseUrl){totalWeight += baseUrl.dvb_weight;cumulWeights.push(totalWeight);}); // pick a random number between zero and totalWeight
rn = Math.floor(Math.random() * (totalWeight - 1)); // select the index for the range rn falls within
cumulWeights.every(function(limit,index){idx = index;if(rn < limit){return false;}return true;});}return urls[idx];}}function select(baseUrls){return baseUrls && selectByWeight(getNonBlacklistedBaseUrls(baseUrls));}instance = {select:select};return instance;}DVBSelector.__dashjs_factory_name = 'DVBSelector';exports['default'] = _coreFactoryMaker2['default'].getClassFactory(DVBSelector);module.exports = exports['default'];
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