Sub-sample accurate start of OscillatorNode

third_party/WebKit/Source/modules/webaudio/AudioScheduledSourceNode.h

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 70 matching lines @@
   // Get frame information for the current time quantum.
   // We handle the transition into PLAYING_STATE and FINISHED_STATE here,
   // zeroing out portions of the outputBus which are outside the range of
   // startFrame and endFrame.
   //
   // Each frame time is relative to the context's currentSampleFrame().
   // quantumFrameOffset    : Offset frame in this time quantum to start
   //                         rendering.
   // nonSilentFramesToProcess : Number of frames rendering non-silence (will be
   //                            <= quantumFrameSize).
+  // startFrameOffset : The fractional frame offset from quantumFrameOffset
+  //                    and the actual starting time of the source. This is
+  //                    non-zero only when transitioning from the
+  //                    SCHEDULED_STATE to the PLAYING_STATE.
   void updateSchedulingInfo(size_t quantumFrameSize,
                             AudioBus* outputBus,
                             size_t& quantumFrameOffset,
-                            size_t& nonSilentFramesToProcess);
+                            size_t& nonSilentFramesToProcess,
+                            double& startFrameOffset);
 
   // Called when we have no more sound to play or the stop() time has been
   // reached. No onEnded event is called.
   virtual void finishWithoutOnEnded();
 
   // Like finishWithoutOnEnded(), but an onEnded (if specified) is called.
   virtual void finish();
 
   void notifyEnded();
 
@@ skipping 40 matching lines @@
   DEFINE_INLINE_VIRTUAL_TRACE() { AudioNode::trace(visitor); }
 
  protected:
   explicit AudioScheduledSourceNode(BaseAudioContext&);
   AudioScheduledSourceHandler& audioScheduledSourceHandler() const;
 };
 
 }  // namespace blink
 
 #endif  // AudioScheduledSourceNode_h