Bug 469275 - Seeks requested while Wave state machine is in ended state are lost. r+sr=roc

--HG--
extra : rebase_source : 03ead0a2032ac705b2156bb1b02aef33a414c67b

content/media/video/src/nsWaveDecoder.cpp

@@ -354,6 +354,9 @@ private:
   // run.  This allows coalescing of these events as they can be produced
   // many times per second.
   PRPackedBool mPositionChangeQueued;
+
+  // True if paused.  Tracks only the play/paused state.
+  PRPackedBool mPaused;
 };
 
 nsWaveStateMachine::nsWaveStateMachine(nsWaveDecoder* aDecoder, nsMediaStream* aStream,
@@ -379,7 +382,8 @@ nsWaveStateMachine::nsWaveStateMachine(nsWaveDecoder* aDecoder, nsMediaStream* a
     mTimeOffset(0),
     mSeekTime(0.0),
     mMetadataValid(PR_FALSE),
-    mPositionChangeQueued(PR_FALSE)
+    mPositionChangeQueued(PR_FALSE),
+    mPaused(mNextState == STATE_PAUSED)
 {
   mMonitor = nsAutoMonitor::NewMonitor("nsWaveStateMachine");
   mDownloadStatistics.Start(PR_IntervalNow());
@@ -400,6 +404,7 @@ void
 nsWaveStateMachine::Play()
 {
   nsAutoMonitor monitor(mMonitor);
+  mPaused = PR_FALSE;
   if (mState == STATE_LOADING_METADATA || mState == STATE_SEEKING) {
     mNextState = STATE_PLAYING;
   } else {
@@ -431,6 +436,7 @@ void
 nsWaveStateMachine::Pause()
 {
   nsAutoMonitor monitor(mMonitor);
+  mPaused = PR_TRUE;
   if (mState == STATE_LOADING_METADATA || mState == STATE_SEEKING) {
     mNextState = STATE_PAUSED;
   } else {
@@ -722,14 +728,21 @@ nsWaveStateMachine::Run()
         }
 
         if (mState == STATE_SEEKING && mSeekTime == seekTime) {
-          // Special case: if a seek was requested during metadata load,
+          // Special case #1: if a seek was requested during metadata load,
           // mNextState will have been clobbered.  This can only happen when
           // we're instantiating a decoder to service a seek request after
           // playback has ended, so we know that the clobbered mNextState
           // was PAUSED.
+          // Special case #2: if a seek is requested after the state machine
+          // entered STATE_ENDED but before the user has seen the ended
+          // event, playback has not ended as far as the user's
+          // concerned--the state machine needs to return to the last
+          // playback state.
           State nextState = mNextState;
           if (nextState == STATE_SEEKING) {
             nextState = STATE_PAUSED;
+          } else if (nextState == STATE_ENDED) {
+            nextState = mPaused ? STATE_PAUSED : STATE_PLAYING;
           }
           ChangeState(nextState);
         }
@@ -757,14 +770,14 @@ nsWaveStateMachine::Run()
         monitor.Enter();
       }
 
-      if (mState != STATE_SHUTDOWN) {
+      if (mState == STATE_ENDED) {
         nsCOMPtr<nsIRunnable> event =
           NS_NEW_RUNNABLE_METHOD(nsWaveDecoder, mDecoder, PlaybackEnded);
         NS_DispatchToMainThread(event, NS_DISPATCH_NORMAL);
-      }
 
-      while (mState != STATE_SHUTDOWN) {
-        monitor.Wait();
+        do {
+          monitor.Wait();
+        } while (mState == STATE_ENDED);
       }
       break;
 
@@ -823,6 +836,9 @@ IsValidStateTransition(State aStartState, State aEndState)
       return PR_TRUE;
     break;
   case STATE_ENDED:
+    if (aEndState == STATE_SEEKING)
+      return PR_TRUE;
+    /* fallthrough */
   case STATE_ERROR:
   case STATE_SHUTDOWN:
     break;
@@ -1428,6 +1444,10 @@ nsWaveDecoder::PlaybackEnded()
     return;
   }
 
+  if (!mPlaybackStateMachine->IsEnded()) {
+    return;
+  }
+
   Stop();
   if (mElement) {
     mElement->PlaybackEnded();