Port bandwidth selector from http-streaming @ v2.0.0
Reference: https://github.com/videojs/http-streaming/issues/749#issuecomment-606972884 This is a direct copy of the necessary files to replicate `lastBandwidthSelector`. Irrelevant code was removed.
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export default {
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GOAL_BUFFER_LENGTH: 30,
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MAX_GOAL_BUFFER_LENGTH: 60,
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GOAL_BUFFER_LENGTH_RATE: 1,
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// 0.5 MB/s
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INITIAL_BANDWIDTH: 4194304,
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// A fudge factor to apply to advertised playlist bitrates to account for
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// temporary flucations in client bandwidth
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BANDWIDTH_VARIANCE: 1.2,
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// How much of the buffer must be filled before we consider upswitching
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BUFFER_LOW_WATER_LINE: 0,
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MAX_BUFFER_LOW_WATER_LINE: 30,
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BUFFER_LOW_WATER_LINE_RATE: 1,
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};
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import window from 'global/window';
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import Config from './config';
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import Playlist from './playlist';
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// Utilities
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/**
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* Returns the CSS value for the specified property on an element
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* using `getComputedStyle`. Firefox has a long-standing issue where
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* getComputedStyle() may return null when running in an iframe with
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* `display: none`.
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*
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* @see https://bugzilla.mozilla.org/show_bug.cgi?id=548397
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* @param {HTMLElement} el the htmlelement to work on
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* @param {string} the proprety to get the style for
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*/
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const safeGetComputedStyle = function(el, property) {
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if (!el) {
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return '';
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}
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const result = window.getComputedStyle(el);
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if (!result) {
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return '';
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}
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return result[property];
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};
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/**
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* Resuable stable sort function
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*
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* @param {Playlists} array
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* @param {Function} sortFn Different comparators
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* @function stableSort
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*/
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const stableSort = function(array, sortFn) {
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const newArray = array.slice();
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array.sort(function(left, right) {
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const cmp = sortFn(left, right);
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if (cmp === 0) {
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return newArray.indexOf(left) - newArray.indexOf(right);
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}
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return cmp;
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});
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};
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/**
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* Chooses the appropriate media playlist based on bandwidth and player size
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*
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* @param {Object} master
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* Object representation of the master manifest
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* @param {number} playerBandwidth
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* Current calculated bandwidth of the player
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* @param {number} playerWidth
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* Current width of the player element (should account for the device
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* pixel ratio)
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* @param {number} playerHeight
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* Current height of the player element (should account for the device
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* pixel ratio)
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* @param {boolean} limitRenditionByPlayerDimensions
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* True if the player width and height should be used during the
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* selection, false otherwise
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* @return {Playlist} the highest bitrate playlist less than the
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* currently detected bandwidth, accounting for some amount of
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* bandwidth variance
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*/
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export const simpleSelector = function(
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master,
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playerBandwidth,
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playerWidth,
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playerHeight,
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limitRenditionByPlayerDimensions
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) {
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// convert the playlists to an intermediary representation to make comparisons easier
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let sortedPlaylistReps = master.playlists.map((playlist) => {
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let bandwidth;
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const width = playlist.attributes.RESOLUTION && playlist.attributes.RESOLUTION.width;
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const height = playlist.attributes.RESOLUTION && playlist.attributes.RESOLUTION.height;
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bandwidth = playlist.attributes.BANDWIDTH;
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bandwidth = bandwidth || window.Number.MAX_VALUE;
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return {
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bandwidth,
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width,
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height,
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playlist
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};
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});
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stableSort(sortedPlaylistReps, (left, right) => left.bandwidth - right.bandwidth);
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// filter out any playlists that have been excluded due to
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// incompatible configurations
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sortedPlaylistReps = sortedPlaylistReps.filter((rep) => !Playlist.isIncompatible(rep.playlist));
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// filter out any playlists that have been disabled manually through the representations
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// api or blacklisted temporarily due to playback errors.
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let enabledPlaylistReps = sortedPlaylistReps.filter((rep) => Playlist.isEnabled(rep.playlist));
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if (!enabledPlaylistReps.length) {
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// if there are no enabled playlists, then they have all been blacklisted or disabled
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// by the user through the representations api. In this case, ignore blacklisting and
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// fallback to what the user wants by using playlists the user has not disabled.
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enabledPlaylistReps = sortedPlaylistReps.filter((rep) => !Playlist.isDisabled(rep.playlist));
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}
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// filter out any variant that has greater effective bitrate
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// than the current estimated bandwidth
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const bandwidthPlaylistReps = enabledPlaylistReps.filter((rep) => rep.bandwidth * Config.BANDWIDTH_VARIANCE < playerBandwidth);
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let highestRemainingBandwidthRep =
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bandwidthPlaylistReps[bandwidthPlaylistReps.length - 1];
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// get all of the renditions with the same (highest) bandwidth
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// and then taking the very first element
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const bandwidthBestRep = bandwidthPlaylistReps.filter((rep) => rep.bandwidth === highestRemainingBandwidthRep.bandwidth)[0];
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// if we're not going to limit renditions by player size, make an early decision.
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if (limitRenditionByPlayerDimensions === false) {
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const chosenRep = (
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bandwidthBestRep ||
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enabledPlaylistReps[0] ||
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sortedPlaylistReps[0]
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);
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return chosenRep ? chosenRep.playlist : null;
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}
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// filter out playlists without resolution information
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const haveResolution = bandwidthPlaylistReps.filter((rep) => rep.width && rep.height);
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// sort variants by resolution
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stableSort(haveResolution, (left, right) => left.width - right.width);
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// if we have the exact resolution as the player use it
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const resolutionBestRepList = haveResolution.filter((rep) => rep.width === playerWidth && rep.height === playerHeight);
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highestRemainingBandwidthRep = resolutionBestRepList[resolutionBestRepList.length - 1];
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// ensure that we pick the highest bandwidth variant that have exact resolution
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const resolutionBestRep = resolutionBestRepList.filter((rep) => rep.bandwidth === highestRemainingBandwidthRep.bandwidth)[0];
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let resolutionPlusOneList;
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let resolutionPlusOneSmallest;
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let resolutionPlusOneRep;
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// find the smallest variant that is larger than the player
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// if there is no match of exact resolution
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if (!resolutionBestRep) {
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resolutionPlusOneList = haveResolution.filter((rep) => rep.width > playerWidth || rep.height > playerHeight);
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// find all the variants have the same smallest resolution
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resolutionPlusOneSmallest = resolutionPlusOneList.filter((rep) => rep.width === resolutionPlusOneList[0].width &&
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rep.height === resolutionPlusOneList[0].height);
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// ensure that we also pick the highest bandwidth variant that
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// is just-larger-than the video player
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highestRemainingBandwidthRep =
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resolutionPlusOneSmallest[resolutionPlusOneSmallest.length - 1];
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resolutionPlusOneRep = resolutionPlusOneSmallest.filter((rep) => rep.bandwidth === highestRemainingBandwidthRep.bandwidth)[0];
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}
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// fallback chain of variants
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const chosenRep = (
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resolutionPlusOneRep ||
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resolutionBestRep ||
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bandwidthBestRep ||
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enabledPlaylistReps[0] ||
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sortedPlaylistReps[0]
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);
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return chosenRep ? chosenRep.playlist : null;
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};
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// Playlist Selectors
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/**
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* Chooses the appropriate media playlist based on the most recent
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* bandwidth estimate and the player size.
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*
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* Expects to be called within the context of an instance of VhsHandler
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*
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* @return {Playlist} the highest bitrate playlist less than the
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* currently detected bandwidth, accounting for some amount of
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* bandwidth variance
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*/
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export const lastBandwidthSelector = function() {
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const pixelRatio = this.useDevicePixelRatio ? window.devicePixelRatio || 1 : 1;
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return simpleSelector(
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this.playlists.master,
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this.systemBandwidth,
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parseInt(safeGetComputedStyle(this.tech_.el(), 'width'), 10) * pixelRatio,
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parseInt(safeGetComputedStyle(this.tech_.el(), 'height'), 10) * pixelRatio,
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this.limitRenditionByPlayerDimensions
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);
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};
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/**
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* @file playlist.js
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*
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* Playlist related utilities.
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*/
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/**
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* Check whether the playlist is blacklisted or not.
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*
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* @param {Object} playlist the media playlist object
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* @return {boolean} whether the playlist is blacklisted or not
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* @function isBlacklisted
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*/
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export const isBlacklisted = function(playlist) {
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return playlist.excludeUntil && playlist.excludeUntil > Date.now();
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};
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/**
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* Check whether the playlist is compatible with current playback configuration or has
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* been blacklisted permanently for being incompatible.
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*
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* @param {Object} playlist the media playlist object
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* @return {boolean} whether the playlist is incompatible or not
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* @function isIncompatible
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*/
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export const isIncompatible = function(playlist) {
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return playlist.excludeUntil && playlist.excludeUntil === Infinity;
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};
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/**
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* Check whether the playlist is enabled or not.
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*
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* @param {Object} playlist the media playlist object
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* @return {boolean} whether the playlist is enabled or not
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* @function isEnabled
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*/
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export const isEnabled = function(playlist) {
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const blacklisted = isBlacklisted(playlist);
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return (!playlist.disabled && !blacklisted);
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};
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/**
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* Check whether the playlist has been manually disabled through the representations api.
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*
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* @param {Object} playlist the media playlist object
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* @return {boolean} whether the playlist is disabled manually or not
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* @function isDisabled
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*/
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export const isDisabled = function(playlist) {
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return playlist.disabled;
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};
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export default {
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isEnabled,
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isDisabled,
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isBlacklisted,
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isIncompatible,
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};
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