Limit Chromecast playback to 1080p

Original Chromecast devices can output a max of 1080p, and may have
issues digesting higher resolution content.  Since higher resolution
content would be downscaled for display anyway, limit Chromecast to
1080p to avoid both decoder issues and wasted bandwidth.

Some Cast devices may support UHD content, but the max res for
Chromecast is currently hard-coded until we have a way to detect a
device's capabilities at runtime.

Issue #261

Change-Id: I3dd093b07f9a964116f81422f3c298dfbf7e2e52

lib/cast/cast_receiver.js

@@ -141,6 +141,11 @@ shaka.cast.CastReceiver.prototype.init_ = function() {
     this.player_.addEventListener(name, this.proxyEvent_.bind(this, 'player'));
   }.bind(this));
 
+  // Limit streams to 1080p.  In our tests, the original Chromecast seems to
+  // have trouble decoding above this limit.  It would be a waste to select a
+  // higher res anyway, given that the device only outputs 1080p to begin with.
+  this.player_.setMaxHardwareResolution(1920, 1080);
+
   // Start polling.
   this.pollAttributes_();
 };

lib/offline/storage.js

@@ -536,7 +536,8 @@ shaka.offline.Storage.prototype.filterPeriod_ = function(period) {
   }
   StreamUtils.filterPeriod(this.drmEngine_, activeStreams, period);
   StreamUtils.applyRestrictions(
-      period, this.player_.getConfiguration().restrictions);
+      period, this.player_.getConfiguration().restrictions,
+      /* maxHwRes */ { width: Infinity, height: Infinity });
 };
 
 

lib/player.js

@@ -130,6 +130,9 @@ shaka.Player = function(video, opt_dependencyInjector) {
   /** @private {?shakaExtern.PlayerConfiguration} */
   this.config_ = this.defaultConfig_();
 
+  /** @private {{width: number, height: number}} */
+  this.maxHwRes_ = { width: Infinity, height: Infinity };
+
   /** @private {!Array.<shakaExtern.StreamChoice>} */
   this.switchHistory_ = [];
 
@@ -1032,6 +1035,21 @@ shaka.Player.prototype.addTextTrack = function(
 };
 
 
+/**
+ * Set the maximum resolution that the platform's hardware can handle.
+ * This will be called automatically by shaka.cast.CastReceiver to enforce
+ * limitations of the Chromecast hardware.
+ *
+ * @param {number} width
+ * @param {number} height
+ * @export
+ */
+shaka.Player.prototype.setMaxHardwareResolution = function(width, height) {
+  this.maxHwRes_.width = width;
+  this.maxHwRes_.height = height;
+};
+
+
 /**
  * Initialize the Player.
  * @private
@@ -1230,7 +1248,7 @@ shaka.Player.prototype.filterPeriod_ = function(period) {
       period.streamSets.some(shaka.util.StreamUtils.hasPlayableStreams);
 
   var tracksChanged = shaka.util.StreamUtils.applyRestrictions(
-      period, this.config_.restrictions);
+      period, this.config_.restrictions, this.maxHwRes_);
   if (tracksChanged && !this.loadChain_)
     this.onTracksChanged_();
 

lib/util/stream_utils.js

@@ -27,9 +27,15 @@ goog.require('shaka.util.LanguageUtils');
 /**
  * @param {shakaExtern.Period} period
  * @param {shakaExtern.Restrictions} restrictions
+ *   Configured restrictions from the user.
+ * @param {{width: number, height: number}} maxHwRes
+ *   The maximum resolution the hardware can handle.
+ *   This is applied separately from user restrictions because the setting
+ *   should not be easily replaced by the user's configuration.
  * @return {boolean} Whether the tracks changed.
  */
-shaka.util.StreamUtils.applyRestrictions = function(period, restrictions) {
+shaka.util.StreamUtils.applyRestrictions =
+    function(period, restrictions, maxHwRes) {
   var tracksChanged = false;
 
   period.streamSets.forEach(function(streamSet) {
@@ -40,8 +46,10 @@ shaka.util.StreamUtils.applyRestrictions = function(period, restrictions) {
       if (streamSet.type == 'video') {
         if (stream.width < restrictions.minWidth ||
             stream.width > restrictions.maxWidth ||
+            stream.width > maxHwRes.width ||
             stream.height < restrictions.minHeight ||
             stream.height > restrictions.maxHeight ||
+            stream.height > maxHwRes.height ||
             (stream.width * stream.height) < restrictions.minPixels ||
             (stream.width * stream.height) > restrictions.maxPixels ||
             stream.bandwidth < restrictions.minVideoBandwidth ||

test/cast/cast_receiver_unit.js

@@ -104,6 +104,12 @@ describe('CastReceiver', function() {
       expect(Object.keys(mockPlayer.listeners).length).toBeGreaterThan(0);
     });
 
+    it('limits streams to 1080p', function() {
+      checkChromeOrChromecast();
+      expect(mockPlayer.setMaxHardwareResolution).
+          toHaveBeenCalledWith(1920, 1080);
+    });
+
     it('starts polling', function(done) {
       checkChromeOrChromecast();
       var fakeConfig = {key: 'value'};
@@ -592,6 +598,7 @@ describe('CastReceiver', function() {
       seekRange: jasmine.createSpy('seekRange'),
       configure: jasmine.createSpy('configure'),
       setTextTrackVisibility: jasmine.createSpy('setTextTrackVisibility'),
+      setMaxHardwareResolution: jasmine.createSpy('setMaxHardwareResolution'),
       load: jasmine.createSpy('load'),
       destroy: jasmine.createSpy('destroy'),
       addEventListener: function(eventName, listener) {