feat: add an option to ignore player size in selection logic (#238)

README.md

@@ -333,6 +333,15 @@ When `enableLowInitialPlaylist` is set to true, it will be used to select
 the lowest bitrate playlist initially.  This helps to decrease playback start time.
 This setting is `false` by default.
 
+##### limitRenditionByPlayerDimensions
+* Type: `boolean`
+* can be used as an initialization option
+
+When `limitRenditionByPlayerDimensions` is set to true, rendition
+selection logic will take into account the player size and rendition
+resolutions when making a decision.
+This setting is `true` by default.
+
 ### Runtime Properties
 Runtime properties are attached to the tech object when HLS is in
 use. You can get a reference to the HLS source handler like this:

src/config.js

@@ -2,6 +2,8 @@ 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,

src/playlist-selectors.js

@@ -124,6 +124,8 @@ export const comparePlaylistResolution = function(left, right) {
  *        Current width of the player element
  * @param {Number} playerHeight
  *        Current height of the player element
+ * @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
@@ -131,7 +133,8 @@ export const comparePlaylistResolution = function(left, right) {
 export const simpleSelector = function(master,
                                        playerBandwidth,
                                        playerWidth,
-                                       playerHeight) {
+                                       playerHeight,
+                                       limitRenditionByPlayerDimensions) {
   // convert the playlists to an intermediary representation to make comparisons easier
   let sortedPlaylistReps = master.playlists.map((playlist) => {
     let width;
@@ -190,6 +193,17 @@ export const simpleSelector = function(master,
     (rep) => rep.bandwidth === highestRemainingBandwidthRep.bandwidth
   )[0];
 
+  // if we're not going to limit renditions by player size, make an early decision.
+  if (limitRenditionByPlayerDimensions === false) {
+    let chosenRep = (
+      bandwidthBestRep ||
+      enabledPlaylistReps[0] ||
+      sortedPlaylistReps[0]
+    );
+
+    return chosenRep ? chosenRep.playlist : null;
+  }
+
   // filter out playlists without resolution information
   let haveResolution = bandwidthPlaylistReps.filter((rep) => rep.width && rep.height);
 
@@ -261,7 +275,8 @@ export const lastBandwidthSelector = function() {
   return simpleSelector(this.playlists.master,
                         this.systemBandwidth,
                         parseInt(safeGetComputedStyle(this.tech_.el(), 'width'), 10),
-                        parseInt(safeGetComputedStyle(this.tech_.el(), 'height'), 10));
+                        parseInt(safeGetComputedStyle(this.tech_.el(), 'height'), 10),
+                        this.limitRenditionByPlayerDimensions);
 };
 
 /**
@@ -294,7 +309,8 @@ export const movingAverageBandwidthSelector = function(decay) {
     return simpleSelector(this.playlists.master,
                           average,
                           parseInt(safeGetComputedStyle(this.tech_.el(), 'width'), 10),
-                          parseInt(safeGetComputedStyle(this.tech_.el(), 'height'), 10));
+                          parseInt(safeGetComputedStyle(this.tech_.el(), 'height'), 10),
+                          this.limitRenditionByPlayerDimensions);
   };
 };
 

src/videojs-http-streaming.js

@@ -44,9 +44,6 @@ const Hls = {
   xhr: xhrFactory()
 };
 
-// 0.5 MB/s
-const INITIAL_BANDWIDTH = 4194304;
-
 // Define getter/setters for config properites
 [
   'GOAL_BUFFER_LENGTH',
@@ -335,6 +332,7 @@ class HlsHandler extends Component {
   setOptions_() {
     // defaults
     this.options_.withCredentials = this.options_.withCredentials || false;
+    this.options_.limitRenditionByPlayerDimensions = this.options_.limitRenditionByPlayerDimensions === false ? false : true;
 
     if (typeof this.options_.blacklistDuration !== 'number') {
       this.options_.blacklistDuration = 5 * 60;
@@ -343,23 +341,24 @@ class HlsHandler extends Component {
     // start playlist selection at a reasonable bandwidth for
     // broadband internet (0.5 MB/s) or mobile (0.0625 MB/s)
     if (typeof this.options_.bandwidth !== 'number') {
-      this.options_.bandwidth = INITIAL_BANDWIDTH;
+      this.options_.bandwidth = Config.INITIAL_BANDWIDTH;
     }
 
     // If the bandwidth number is unchanged from the initial setting
     // then this takes precedence over the enableLowInitialPlaylist option
     this.options_.enableLowInitialPlaylist =
       this.options_.enableLowInitialPlaylist &&
-      this.options_.bandwidth === INITIAL_BANDWIDTH;
+      this.options_.bandwidth === Config.INITIAL_BANDWIDTH;
 
     // grab options passed to player.src
-    ['withCredentials', 'bandwidth'].forEach((option) => {
+    ['withCredentials', 'limitRenditionByPlayerDimensions', 'bandwidth'].forEach((option) => {
       if (typeof this.source_[option] !== 'undefined') {
         this.options_[option] = this.source_[option];
       }
     });
 
     this.bandwidth = this.options_.bandwidth;
+    this.limitRenditionByPlayerDimensions = this.options_.limitRenditionByPlayerDimensions;
   }
   /**
    * called when player.src gets called, handle a new source

test/configuration.test.js

@@ -23,6 +23,11 @@ const options = [{
   default: false,
   test: true,
   alt: false
+}, {
+  name: 'limitRenditionByPlayerDimensions',
+  default: true,
+  test: false,
+  alt: false
 }, {
   name: 'bandwidth',
   default: 4194304,

test/playlist-selectors.test.js

@@ -163,7 +163,39 @@ test('simpleSelector switches up even without resolution information', function(
     { attributes: { BANDWIDTH: 1000 } }
   ];
 
-  const selectedPlaylist = simpleSelector(master, 2000, 1, 1);
+  const selectedPlaylist = simpleSelector(master, 2000, 1, 1, false);
 
   assert.equal(selectedPlaylist, master.playlists[1], 'selected the correct playlist');
 });
+
+// A set of playlists that were defined using non-traditional encoding.
+// The resolutions were selected using a per-title encoding technique
+// that ensures the resolution maximizes quality at a given bitrate.
+const trickyPlaylists = [
+  { attributes: { BANDWIDTH: 2362080, RESOLUTION: { width: 1280, height: 720 } } },
+  { attributes: { BANDWIDTH: 1390830, RESOLUTION: { width: 1280, height: 720 } } },
+  { attributes: { BANDWIDTH: 866114, RESOLUTION: { width: 1024, height: 576 } } },
+  { attributes: { BANDWIDTH: 573028, RESOLUTION: { width: 768, height: 432 } } },
+  { attributes: { BANDWIDTH: 3482070, RESOLUTION: { width: 1920, height: 1080 } } },
+  { attributes: { BANDWIDTH: 6151620, RESOLUTION: { width: 1920, height: 1080 } } }
+];
+
+test('simpleSelector limits using resolution information when it exists', function(assert) {
+  let master = this.hls.playlists.master;
+
+  master.playlists = trickyPlaylists;
+
+  const selectedPlaylist = simpleSelector(master, Config.INITIAL_BANDWIDTH, 444, 790, true);
+
+  assert.equal(selectedPlaylist, master.playlists[3], 'selected the playlist with the lowest bandwidth higher than player resolution');
+});
+
+test('simpleSelector can not limit based on resolution information', function(assert) {
+  let master = this.hls.playlists.master;
+
+  master.playlists = trickyPlaylists;
+
+  const selectedPlaylist = simpleSelector(master, Config.INITIAL_BANDWIDTH, 444, 790, false);
+
+  assert.equal(selectedPlaylist, master.playlists[4], 'selected a playlist based solely on bandwidth');
+});