From bc7b826e41e2cc96dbc2196d1924045489f35a74 Mon Sep 17 00:00:00 2001
From: Joey Parrish <joeyparrish@google.com>
Date: Tue, 1 Sep 2015 10:21:32 -0700
Subject: [PATCH] Support rewind outside of buffered area

Closes #165

Change-Id: I684560b332808f9acffcfc09ad8fffcd8c164fba
---
 lib/player/player.js       | 37 +++++++++++++++++++++++++++----------
 spec/player_integration.js | 23 +++++++++++++++++++++++
 2 files changed, 50 insertions(+), 10 deletions(-)

diff --git a/lib/player/player.js b/lib/player/player.js
index 9c472ffc62..3417162bfe 100644
--- a/lib/player/player.js
+++ b/lib/player/player.js
@@ -98,6 +98,9 @@ shaka.player.Player = function(video) {
   /** @private {?number} */
   this.rewindTimer_ = null;
 
+  /** @private {number} */
+  this.seekRangeStart_ = 0;
+
   /** @private {?number} */
   this.watchdogTimer_ = null;
 
@@ -281,6 +284,8 @@ shaka.player.Player.prototype.load = function(videoSource) {
       function() {
         this.videoSource_ = videoSource;
         this.videoSource_.setRestrictions(this.restrictions_);
+        this.eventManager_.listen(this.videoSource_, 'seekrangechanged',
+                                  this.onSeekRangeChanged_.bind(this));
         this.emeManager_ = new shaka.media.EmeManager(
             this, this.video_, this.videoSource_);
         return this.emeManager_.initialize();
@@ -416,7 +421,17 @@ shaka.player.Player.prototype.onPause_ = function(event) {
   if (!isNaN(elapsed)) {
     this.stats_.logPlayTime(elapsed);
   }
-  this.cancelRewindTimer_();
+};
+
+
+/**
+ * Handler for seek range events.
+ *
+ * @param {!Event} event
+ * @private
+ */
+shaka.player.Player.prototype.onSeekRangeChanged_ = function(event) {
+  this.seekRangeStart_ = event['start'];
 };
 
 
@@ -881,19 +896,21 @@ shaka.player.Player.prototype.cancelWatchdogTimer_ = function() {
 shaka.player.Player.prototype.onRewindTimer_ =
     function(startVideoTime, startWallTime, rate) {
   shaka.asserts.assert(rate < 0);
-  var rewindOffset =
-      shaka.player.Player.REWIND_UPDATE_INTERVAL_ * Math.abs(rate);
-  if (this.video_.buffered.length &&
-      this.video_.buffered.start(0) + rewindOffset < this.video_.currentTime) {
-    var offset = ((Date.now() - startWallTime) / 1000) * rate;
-    this.video_.currentTime = startVideoTime + offset;
+  this.rewindTimer_ = null;
+
+  var offset = ((Date.now() - startWallTime) / 1000) * rate;
+  var fudge = this.isLive() ? 1 : 0.05;
 
+  if (this.video_.currentTime < this.seekRangeStart_ + fudge) {
+    // Hit the beginning (or near enough), so pause.
+    this.video_.pause();
+  } else {
+    var goal = Math.max(this.seekRangeStart_, startVideoTime + offset);
+    this.video_.currentTime = goal;
     var callback = this.onRewindTimer_.bind(
         this, startVideoTime, startWallTime, rate);
     this.rewindTimer_ = window.setTimeout(
         callback, shaka.player.Player.REWIND_UPDATE_INTERVAL_ * 1000);
-  } else {
-    this.video_.pause();
   }
 };
 
@@ -991,7 +1008,7 @@ shaka.player.Player.BUFFERED_FUDGE_FACTOR_ = 0.05;
  * @private {number}
  * @const
  */
-shaka.player.Player.REWIND_UPDATE_INTERVAL_ = 0.1;
+shaka.player.Player.REWIND_UPDATE_INTERVAL_ = 0.25;
 
 
 /**
diff --git a/spec/player_integration.js b/spec/player_integration.js
index e352d784dd..ff7a01a775 100644
--- a/spec/player_integration.js
+++ b/spec/player_integration.js
@@ -544,6 +544,29 @@ describe('Player', function() {
         done();
       });
     });
+
+    it('plays in reverse past the buffered area', function(done) {
+      var timestamp = 10;
+      // Start in the second segment.
+      player.load(newSource(plainManifest)).then(function() {
+        video.currentTime = timestamp;
+        video.play();
+        return waitForMovement(video, eventManager);
+      }).then(function() {
+        expect(video.buffered.length).toBe(1);
+        expect(video.buffered.start(0)).toBeGreaterThan(5);
+        player.setPlaybackRate(-3.0);
+        return waitForMovement(video, eventManager);
+      }).then(function() {
+        return delay(4.0);
+      }).then(function() {
+        expect(video.currentTime).toBeLessThan(0.1);
+        done();
+      }).catch(function(error) {
+        fail(error);
+        done();
+      });
+    });
   });
 
   describe('getStats', function() {