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.

ui/component/viewers/videoViewer/internal/plugins/videojs-http-streaming--override/config.js

@@ -0,0 +1,14 @@
+export default {
+  GOAL_BUFFER_LENGTH: 30,
+  MAX_GOAL_BUFFER_LENGTH: 60,
+  GOAL_BUFFER_LENGTH_RATE: 1,
+  // 0.5 MB/s
+  INITIAL_BANDWIDTH: 4194304,
+  // A fudge factor to apply to advertised playlist bitrates to account for
+  // temporary flucations in client bandwidth
+  BANDWIDTH_VARIANCE: 1.2,
+  // How much of the buffer must be filled before we consider upswitching
+  BUFFER_LOW_WATER_LINE: 0,
+  MAX_BUFFER_LOW_WATER_LINE: 30,
+  BUFFER_LOW_WATER_LINE_RATE: 1,
+};

ui/component/viewers/videoViewer/internal/plugins/videojs-http-streaming--override/playlist-selectors.js

@@ -0,0 +1,202 @@
+import window from 'global/window';
+import Config from './config';
+import Playlist from './playlist';
+
+// Utilities
+
+/**
+ * Returns the CSS value for the specified property on an element
+ * using `getComputedStyle`. Firefox has a long-standing issue where
+ * getComputedStyle() may return null when running in an iframe with
+ * `display: none`.
+ *
+ * @see https://bugzilla.mozilla.org/show_bug.cgi?id=548397
+ * @param {HTMLElement} el the htmlelement to work on
+ * @param {string} the proprety to get the style for
+ */
+const safeGetComputedStyle = function(el, property) {
+  if (!el) {
+    return '';
+  }
+
+  const result = window.getComputedStyle(el);
+
+  if (!result) {
+    return '';
+  }
+
+  return result[property];
+};
+
+/**
+ * Resuable stable sort function
+ *
+ * @param {Playlists} array
+ * @param {Function} sortFn Different comparators
+ * @function stableSort
+ */
+const stableSort = function(array, sortFn) {
+  const newArray = array.slice();
+
+  array.sort(function(left, right) {
+    const cmp = sortFn(left, right);
+
+    if (cmp === 0) {
+      return newArray.indexOf(left) - newArray.indexOf(right);
+    }
+    return cmp;
+  });
+};
+
+/**
+ * Chooses the appropriate media playlist based on bandwidth and player size
+ *
+ * @param {Object} master
+ *        Object representation of the master manifest
+ * @param {number} playerBandwidth
+ *        Current calculated bandwidth of the player
+ * @param {number} playerWidth
+ *        Current width of the player element (should account for the device
+ *   pixel ratio)
+ * @param {number} playerHeight
+ *        Current height of the player element (should account for the device
+ *   pixel ratio)
+ * @param {boolean} limitRenditionByPlayerDimensions
+ *        True if the player width and height should be used during the
+ *   selection, false otherwise
+ * @return {Playlist} the highest bitrate playlist less than the
+ * currently detected bandwidth, accounting for some amount of
+ * bandwidth variance
+ */
+export const simpleSelector = function(
+  master,
+  playerBandwidth,
+  playerWidth,
+  playerHeight,
+  limitRenditionByPlayerDimensions
+) {
+  // convert the playlists to an intermediary representation to make comparisons easier
+  let sortedPlaylistReps = master.playlists.map((playlist) => {
+    let bandwidth;
+    const width = playlist.attributes.RESOLUTION && playlist.attributes.RESOLUTION.width;
+    const height = playlist.attributes.RESOLUTION && playlist.attributes.RESOLUTION.height;
+
+    bandwidth = playlist.attributes.BANDWIDTH;
+
+    bandwidth = bandwidth || window.Number.MAX_VALUE;
+
+    return {
+      bandwidth,
+      width,
+      height,
+      playlist
+    };
+  });
+
+  stableSort(sortedPlaylistReps, (left, right) => left.bandwidth - right.bandwidth);
+
+  // filter out any playlists that have been excluded due to
+  // incompatible configurations
+  sortedPlaylistReps = sortedPlaylistReps.filter((rep) => !Playlist.isIncompatible(rep.playlist));
+
+  // filter out any playlists that have been disabled manually through the representations
+  // api or blacklisted temporarily due to playback errors.
+  let enabledPlaylistReps = sortedPlaylistReps.filter((rep) => Playlist.isEnabled(rep.playlist));
+
+  if (!enabledPlaylistReps.length) {
+    // if there are no enabled playlists, then they have all been blacklisted or disabled
+    // by the user through the representations api. In this case, ignore blacklisting and
+    // fallback to what the user wants by using playlists the user has not disabled.
+    enabledPlaylistReps = sortedPlaylistReps.filter((rep) => !Playlist.isDisabled(rep.playlist));
+  }
+
+  // filter out any variant that has greater effective bitrate
+  // than the current estimated bandwidth
+  const bandwidthPlaylistReps = enabledPlaylistReps.filter((rep) => rep.bandwidth * Config.BANDWIDTH_VARIANCE < playerBandwidth);
+
+  let highestRemainingBandwidthRep =
+    bandwidthPlaylistReps[bandwidthPlaylistReps.length - 1];
+
+  // get all of the renditions with the same (highest) bandwidth
+  // and then taking the very first element
+  const bandwidthBestRep = bandwidthPlaylistReps.filter((rep) => rep.bandwidth === highestRemainingBandwidthRep.bandwidth)[0];
+
+  // if we're not going to limit renditions by player size, make an early decision.
+  if (limitRenditionByPlayerDimensions === false) {
+    const chosenRep = (
+      bandwidthBestRep ||
+      enabledPlaylistReps[0] ||
+      sortedPlaylistReps[0]
+    );
+
+    return chosenRep ? chosenRep.playlist : null;
+  }
+
+  // filter out playlists without resolution information
+  const haveResolution = bandwidthPlaylistReps.filter((rep) => rep.width && rep.height);
+
+  // sort variants by resolution
+  stableSort(haveResolution, (left, right) => left.width - right.width);
+
+  // if we have the exact resolution as the player use it
+  const resolutionBestRepList = haveResolution.filter((rep) => rep.width === playerWidth && rep.height === playerHeight);
+
+  highestRemainingBandwidthRep = resolutionBestRepList[resolutionBestRepList.length - 1];
+  // ensure that we pick the highest bandwidth variant that have exact resolution
+  const resolutionBestRep = resolutionBestRepList.filter((rep) => rep.bandwidth === highestRemainingBandwidthRep.bandwidth)[0];
+
+  let resolutionPlusOneList;
+  let resolutionPlusOneSmallest;
+  let resolutionPlusOneRep;
+
+  // find the smallest variant that is larger than the player
+  // if there is no match of exact resolution
+  if (!resolutionBestRep) {
+    resolutionPlusOneList = haveResolution.filter((rep) => rep.width > playerWidth || rep.height > playerHeight);
+
+    // find all the variants have the same smallest resolution
+    resolutionPlusOneSmallest = resolutionPlusOneList.filter((rep) => rep.width === resolutionPlusOneList[0].width &&
+               rep.height === resolutionPlusOneList[0].height);
+
+    // ensure that we also pick the highest bandwidth variant that
+    // is just-larger-than the video player
+    highestRemainingBandwidthRep =
+      resolutionPlusOneSmallest[resolutionPlusOneSmallest.length - 1];
+    resolutionPlusOneRep = resolutionPlusOneSmallest.filter((rep) => rep.bandwidth === highestRemainingBandwidthRep.bandwidth)[0];
+  }
+
+  // fallback chain of variants
+  const chosenRep = (
+    resolutionPlusOneRep ||
+    resolutionBestRep ||
+    bandwidthBestRep ||
+    enabledPlaylistReps[0] ||
+    sortedPlaylistReps[0]
+  );
+
+  return chosenRep ? chosenRep.playlist : null;
+};
+
+// Playlist Selectors
+
+/**
+ * Chooses the appropriate media playlist based on the most recent
+ * bandwidth estimate and the player size.
+ *
+ * Expects to be called within the context of an instance of VhsHandler
+ *
+ * @return {Playlist} the highest bitrate playlist less than the
+ * currently detected bandwidth, accounting for some amount of
+ * bandwidth variance
+ */
+export const lastBandwidthSelector = function() {
+  const pixelRatio = this.useDevicePixelRatio ? window.devicePixelRatio || 1 : 1;
+
+  return simpleSelector(
+    this.playlists.master,
+    this.systemBandwidth,
+    parseInt(safeGetComputedStyle(this.tech_.el(), 'width'), 10) * pixelRatio,
+    parseInt(safeGetComputedStyle(this.tech_.el(), 'height'), 10) * pixelRatio,
+    this.limitRenditionByPlayerDimensions
+  );
+};

ui/component/viewers/videoViewer/internal/plugins/videojs-http-streaming--override/playlist.js

@@ -0,0 +1,59 @@
+/**
+ * @file playlist.js
+ *
+ * Playlist related utilities.
+ */
+
+/**
+ * Check whether the playlist is blacklisted or not.
+ *
+ * @param {Object} playlist the media playlist object
+ * @return {boolean} whether the playlist is blacklisted or not
+ * @function isBlacklisted
+ */
+export const isBlacklisted = function(playlist) {
+  return playlist.excludeUntil && playlist.excludeUntil > Date.now();
+};
+
+/**
+ * Check whether the playlist is compatible with current playback configuration or has
+ * been blacklisted permanently for being incompatible.
+ *
+ * @param {Object} playlist the media playlist object
+ * @return {boolean} whether the playlist is incompatible or not
+ * @function isIncompatible
+ */
+export const isIncompatible = function(playlist) {
+  return playlist.excludeUntil && playlist.excludeUntil === Infinity;
+};
+
+/**
+ * Check whether the playlist is enabled or not.
+ *
+ * @param {Object} playlist the media playlist object
+ * @return {boolean} whether the playlist is enabled or not
+ * @function isEnabled
+ */
+export const isEnabled = function(playlist) {
+  const blacklisted = isBlacklisted(playlist);
+
+  return (!playlist.disabled && !blacklisted);
+};
+
+/**
+ * Check whether the playlist has been manually disabled through the representations api.
+ *
+ * @param {Object} playlist the media playlist object
+ * @return {boolean} whether the playlist is disabled manually or not
+ * @function isDisabled
+ */
+export const isDisabled = function(playlist) {
+  return playlist.disabled;
+};
+
+export default {
+  isEnabled,
+  isDisabled,
+  isBlacklisted,
+  isIncompatible,
+};