Make AbrManager less agressive.

We used to wait until 8 seconds after the last adaptation began.
Now we wait until 30 seconds after the last adaptation completed.

Change-Id: Ibb673d1a2ca45d403a77a037fa3eeea9698d3e31

lib/media/abr_manager.js

@@ -63,6 +63,8 @@ shaka.media.AbrManager = function(estimator, videoSource) {
 
   this.eventManager_.listen(this.estimator_, 'bandwidth',
                             this.onBandwidth_.bind(this));
+  this.eventManager_.listen(this.videoSource_, 'adaptation',
+                            this.onAdaptation_.bind(this));
 };
 
 
@@ -84,7 +86,7 @@ shaka.media.AbrManager.FIRST_SWITCH_INTERVAL_ = 4.0;
  * @private
  * @const {number}
  */
-shaka.media.AbrManager.MIN_SWITCH_INTERVAL_ = 8.0;
+shaka.media.AbrManager.MIN_SWITCH_INTERVAL_ = 30.0;
 
 
 /**
@@ -205,7 +207,26 @@ shaka.media.AbrManager.prototype.onBandwidth_ = function(event) {
     this.videoSource_.selectVideoTrack(chosen.id, false);
   }
 
-  this.nextAdaptationTime_ = now + AbrManager.MIN_SWITCH_INTERVAL_;
+  // Can't adapt again until we get confirmation of this one.
+  this.nextAdaptationTime_ = Number.POSITIVE_INFINITY;
+};
+
+
+/**
+ * Handles adaptation events.
+ *
+ * @param {!Event} event
+ * @private
+ */
+shaka.media.AbrManager.prototype.onAdaptation_ = function(event) {
+  // This check allows us to ignore the initial adaptation events, which would
+  // otherwise cause us not to honor FIRST_SWITCH_INTERVAL_.
+  if (this.nextAdaptationTime_ == Number.POSITIVE_INFINITY) {
+    // Adaptation is complete, so schedule the next adaptation.
+    var now = Date.now() / 1000.0;
+    this.nextAdaptationTime_ =
+        now + shaka.media.AbrManager.MIN_SWITCH_INTERVAL_;
+  }
 };
 
 

lib/media/stream.js

@@ -371,8 +371,6 @@ shaka.media.Stream.prototype.switch = function(streamInfo, immediate) {
 
         this.sbm_.reset();
 
-        this.fireAdaptationEvent_(streamInfo);
-
         // Stop updating and abort |sbm_|'s current operation. This will reject
         // |sbm_|'s current promise.
         this.cancelUpdateTimer_();
@@ -405,6 +403,7 @@ shaka.media.Stream.prototype.switch = function(streamInfo, immediate) {
           }
         }
         shaka.timer.end('switch logic');
+        this.fireAdaptationEvent_(streamInfo);
         this.switchStreamOrUpdate_();
       })
   ).catch(shaka.util.TypedBind(this,