Bug 825329 - Properly implement AudioStream::GetPlaybackRate. r=kinetik

content/media/AudioStream.cpp

@@ -1112,7 +1112,6 @@ AudioClock::AudioClock(AudioStream* aStream)
   mOutRate(0),
   mInRate(0),
   mPreservesPitch(true),
-  mPlaybackRate(1.0),
   mCompensatingLatency(false)
 {}
 
@@ -1120,7 +1119,6 @@ void AudioClock::Init()
 {
   mOutRate = mAudioStream->GetRate();
   mInRate = mAudioStream->GetRate();
-  mPlaybackRate = 1.0;
   mOldOutRate = mOutRate;
 }
 
@@ -1190,7 +1188,7 @@ void AudioClock::SetPlaybackRate(double aPlaybackRate)
 
 double AudioClock::GetPlaybackRate()
 {
-  return mPlaybackRate;
+  return static_cast<double>(mOutRate) / mInRate;
 }
 
 void AudioClock::SetPreservesPitch(bool aPreservesPitch)

content/media/AudioStream.h

@@ -77,8 +77,6 @@ class AudioClock
     int mInRate;
     // True if the we are timestretching, false if we are resampling.
     bool mPreservesPitch;
-    // The current playback rate.
-    double mPlaybackRate;
     // True if we are playing at the old playbackRate after it has been changed.
     bool mCompensatingLatency;
 };

content/media/test/test_playback_rate.html

@@ -107,8 +107,42 @@ function onended(e) {
     ok(!t.muted, "The audio should be muted when playing at high speed, but should not appear as such.");
     is(t.currentTime, t.duration, "Current time should be equal to the duration (not change by playback rate).");
   }
+  testResetPlaybackRate(e);
+}
+
+function testResetPlaybackRate(e) {
+  var t = e.target;
+  t.addEventListener("timeupdate", ontimeupdate_resetPlabackRate);
+  t.currentTime = 0.0;
+  t.play();
+  t.timeUpdate = 0;
+}
+
+function ontimeupdate_resetPlabackRate(e) {
+  var t = e.target;
+  if (t.currentTime == 0.0) {
+    return;
+  }
+  if (t.timeUpdate == 0) {
+    t.playbackRate = 0.5;
+    t.timeUpdate++;
+  } else if (t.timeUpdate == 1){
+    t.playbackRate = 1.0;
+    t.startTimestamp = Date.now();
+    t.oldCurrentTime = t.currentTime;
+    t.timeUpdate++;
+  } else {
+    if (t.currentTime < 3 * t.duration / 4) {
+      return;
+    }
+    var delta = t.currentTime - t.oldCurrentTime,
+        delta_wallclock = (Date.now() - t.startTimestamp - t.bufferingTime) / 1000;
+
+    ok(checkPlaybackRate(delta_wallclock, delta, 1.0, 0.25), "PlaybackRate reset.");
+    t.removeEventListener("timeupdate", ontimeupdate_resetPlabackRate);
     test_defaultPlaybackRate(e);
   }
+}
 
 function test_defaultPlaybackRate(e) {
   var t = e.target;
@@ -135,9 +169,9 @@ function ontimeupdate_defaultPlaybackRate(e) {
         "The default playback rate shoud be "+SLOW_RATE+"." + t.token);
     ok(delta_wallclock > delta , "We are effectively slowing down playback. (" + delta_wallclock + ", " + delta + ")");
     if (t.skippedFastPart) {
-      is(t.ratechangecount, 7, "We should have received 7 \"ratechange\" events.");
+      is(t.ratechangecount, 10, "We should have received 10 \"ratechange\" events.");
     } else {
-      is(t.ratechangecount, 8, "We should have received 8 \"ratechange\" events.");
+      is(t.ratechangecount, 11, "We should have received 11 \"ratechange\" events.");
     }
     finish_test(t);
   }