Merge pull request #17 from yokuze/fix_no_preload_no_resume_play_16

Refs #16 Fix video does not resume playing after quality change

CHANGELOG.md

@@ -3,6 +3,12 @@
 In general, this project adheres to [Semantic Versioning](http://semver.org/). If for some
 reason we do something that's not strictly semantic, it will be clearly called out below.
 
+## 1.1.2
+
+   * Fixed a bug where selecting a quality menu item while a video was playing did not resume
+   playback after the source changed. Affected Safari and players whose `preload` attribute
+   was `none` (8feeafb Fixes #16).
+
 ## 1.1.1
 
    * Reference underscore as a dependency since we depend on it (931d8a4 See #12)

package.json

@@ -26,7 +26,6 @@
   "homepage": "https://github.com/silvermine/videojs-quality-selector#readme",
   "devDependencies": {
     "autoprefixer": "7.1.1",
-    "class.extend": "0.9.2",
     "coveralls": "2.13.1",
     "eslint": "4.0.0",
     "eslint-config-silvermine": "1.3.0",
@@ -51,6 +50,7 @@
     "video.js": "6.x"
   },
   "dependencies": {
+    "class.extend": "0.9.2",
     "underscore": "1.8.3"
   }
 }

src/js/index.js

@@ -3,7 +3,8 @@
 var _ = require('underscore'),
     events = require('./events'),
     qualitySelectorFactory = require('./components/QualitySelector'),
-    sourceInterceptorFactory = require('./middleware/SourceInterceptor');
+    sourceInterceptorFactory = require('./middleware/SourceInterceptor'),
+    SafeSeek = require('./util/SafeSeek');
 
 module.exports = function(videojs) {
    videojs = videojs || window.videojs;
@@ -12,8 +13,7 @@ module.exports = function(videojs) {
    sourceInterceptorFactory(videojs);
 
    videojs.hook('setup', function(player) {
-      // Add handler to switch sources when the user requests a change
-      player.on(events.QUALITY_REQUESTED, function(event, newSource) {
+      function changeQuality(event, newSource) {
          var sources = player.currentSources(),
              currentTime = player.currentTime(),
              isPaused = player.paused(),
@@ -29,15 +29,36 @@ module.exports = function(videojs) {
          // following updates the original object in `sources`.
          selectedSource.selected = true;
 
+         if (player._qualitySelectorSafeSeek) {
+            player._qualitySelectorSafeSeek.onQualitySelectionChange();
+         }
+
          player.src(sources);
 
-         player.one('loadeddata', function() {
-            player.currentTime(currentTime);
+         player.ready(function() {
+            if (!player._qualitySelectorSafeSeek || player._qualitySelectorSafeSeek.hasFinished()) {
+               // Either we don't have a pending seek action or the one that we have is no
+               // longer applicable. This block must be within a `player.ready` callback
+               // because the call to `player.src` above is asynchronous, and so not
+               // having it within this `ready` callback would cause the SourceInterceptor
+               // to execute after this block instead of before.
+               //
+               // We save the `currentTime` within the SafeSeek instance because if
+               // multiple QUALITY_REQUESTED events are received before the SafeSeek
+               // operation finishes, the player's `currentTime` will be `0` if the
+               // player's `src` is updated but the player's `currentTime` has not yet
+               // been set by the SafeSeek operation.
+               player._qualitySelectorSafeSeek = new SafeSeek(player, currentTime);
+            }
+
             if (!isPaused) {
                player.play();
             }
          });
-      });
+      }
+
+      // Add handler to switch sources when the user requests a change
+      player.on(events.QUALITY_REQUESTED, changeQuality);
    });
 };
 

src/js/middleware/SourceInterceptor.js

@@ -13,6 +13,10 @@ module.exports = function(videojs) {
             var sources = player.currentSources(),
                 userSelectedSource, chosenSource;
 
+            if (player._qualitySelectorSafeSeek) {
+               player._qualitySelectorSafeSeek.onPlayerSourcesChange();
+            }
+
             // There are generally two source options, the one that videojs
             // auto-selects and the one that a "user" of this plugin has
             // supplied via the `selected` property. `selected` can come from

src/js/util/SafeSeek.js

@@ -0,0 +1,80 @@
+'use strict';
+
+var Class = require('class.extend');
+
+module.exports = Class.extend({
+   init: function(player, seekToTime) {
+      this._player = player;
+      this._seekToTime = seekToTime;
+      this._hasFinished = false;
+      this._keepThisInstanceWhenPlayerSourcesChange = false;
+      this._seekWhenSafe();
+   },
+
+   _seekWhenSafe: function() {
+      var HAVE_FUTURE_DATA = 3;
+
+      // `readyState` in Video.js is the same as the HTML5 Media element's `readyState`
+      // property.
+      //
+      // `readyState` is an enum of 5 values (0-4), each of which represent a state of
+      // readiness to play. The meaning of the values range from HAVE_NOTHING (0), meaning
+      // no data is available to HAVE_ENOUGH_DATA (4), meaning all data is loaded and the
+      // video can be played all the way through.
+      //
+      // In order to seek successfully, the `readyState` must be at least HAVE_FUTURE_DATA
+      // (3).
+      //
+      // @see http://docs.videojs.com/player#readyState
+      // @see https://developer.mozilla.org/en-US/docs/Web/API/HTMLMediaElement/readyState
+      // @see https://dev.w3.org/html5/spec-preview/media-elements.html#seek-the-media-controller
+      if (this._player.readyState() < HAVE_FUTURE_DATA) {
+         this._seekFn = this._seek.bind(this);
+         // The `canplay` event means that the `readyState` is at least HAVE_FUTURE_DATA.
+         this._player.one('canplay', this._seekFn);
+      } else {
+         this._seek();
+      }
+   },
+
+   onPlayerSourcesChange: function() {
+      if (this._keepThisInstanceWhenPlayerSourcesChange) {
+         // By setting this to `false`, we know that if the player sources change again
+         // the change did not originate from a quality selection change, the new sources
+         // are likely different from the old sources, and so this pending seek no longer
+         // applies.
+         this._keepThisInstanceWhenPlayerSourcesChange = false;
+      } else {
+         this.cancel();
+      }
+   },
+
+   onQualitySelectionChange: function() {
+      // `onPlayerSourcesChange` will cancel this pending seek unless we tell it not to.
+      // We need to reuse this same pending seek instance because when the player is
+      // paused, the `preload` attribute is set to `none`, and the user selects one
+      // quality option and then another, the player cannot seek until the player has
+      // enough data to do so (and the `canplay` event is fired) and thus on the second
+      // selection the player's `currentTime()` is `0` and when the video plays we would
+      // seek to `0` instead of the correct time.
+      if (!this.hasFinished()) {
+         this._keepThisInstanceWhenPlayerSourcesChange = true;
+      }
+   },
+
+   _seek: function() {
+      this._player.currentTime(this._seekToTime);
+      this._keepThisInstanceWhenPlayerSourcesChange = false;
+      this._hasFinished = true;
+   },
+
+   hasFinished: function() {
+      return this._hasFinished;
+   },
+
+   cancel: function() {
+      this._player.off('canplay', this._seekFn);
+      this._keepThisInstanceWhenPlayerSourcesChange = false;
+      this._hasFinished = true;
+   },
+});