[DO NOT SUBMIT] AudioWorklet FS2: audio thread

third_party/WebKit/Source/modules/webaudio/OfflineAudioDestinationNode.cpp

 /*
  * Copyright (C) 2011, 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 145 matching lines @@
 
 void OfflineAudioDestinationHandler::doOfflineRendering()
 {
     ASSERT(!isMainThread());
 
     unsigned numberOfChannels = m_renderTarget->numberOfChannels();
 
     // Reset the suspend flag.
     m_shouldSuspend = false;
 
-    // If there is more to process and there is no suspension at the moment,
-    // do continue to render quanta. Then calling OfflineAudioContext.resume() will pick up
-    // the render loop again from where it was suspended.
+    // If there is more to process and there is no suspension at the moment, do
+    // continue to render quanta. Then calling OfflineAudioContext.resume() will
+    // pick up the render loop again from where it was suspended.
     while (m_framesToProcess > 0 && !m_shouldSuspend) {
 
         // Suspend the rendering and update m_shouldSuspend if a scheduled
         // suspend found at the current sample frame. Otherwise render one
         // quantum and return false.
         m_shouldSuspend = renderIfNotSuspended(0, m_renderBus.get(), renderQuantumSize);
 
         if (m_shouldSuspend)
             return;
 
@@ skipping 85 matching lines @@
     }
 
     // Take care pre-render tasks at the beginning of each render quantum. Then
     // it will stop the rendering loop if the context needs to be suspended
     // at the beginning of the next render quantum.
     if (context()->handlePreOfflineRenderTasks()) {
         suspendOfflineRendering();
         return true;
     }
 
-    // Prepare the local audio input provider for this render quantum.
-    if (sourceBus)
-        m_localAudioInputProvider.set(sourceBus);
+    // TODO(hongchan): OfflineAudioContext does not care about the live input.
+    // Remove this.
+    // if (sourceBus)
+    //     m_localAudioInputProvider.setSourceBus(sourceBus);
 
     ASSERT(numberOfInputs() >= 1);
     if (numberOfInputs() < 1) {
         destinationBus->zero();
         return false;
     }
+
     // This will cause the node(s) connected to us to process, which in turn will pull on their input(s),
     // all the way backwards through the rendering graph.
     AudioBus* renderedBus = input(0).pull(destinationBus, numberOfFrames);
 
+    // TODO(hongchan): this logic should be a part of AudioNodeInput::pull().
     if (!renderedBus) {
         destinationBus->zero();
     } else if (renderedBus != destinationBus) {
-        // in-place processing was not possible - so copy
+        // If the destination node has multiple inputs, in-place processing is
+        // not possible. Thus the explicit copy is necessary.
         destinationBus->copyFrom(*renderedBus);
     }
 
     // Process nodes which need a little extra help because they are not connected to anything, but still need to process.
     context()->deferredTaskHandler().processAutomaticPullNodes(numberOfFrames);
 
     // Let the context take care of any business at the end of each render quantum.
     context()->handlePostOfflineRenderTasks();
 
     // Advance current sample-frame.
@@ skipping 10 matching lines @@
 {
     setHandler(OfflineAudioDestinationHandler::create(*this, renderTarget));
 }
 
 OfflineAudioDestinationNode* OfflineAudioDestinationNode::create(AbstractAudioContext* context, AudioBuffer* renderTarget)
 {
     return new OfflineAudioDestinationNode(*context, renderTarget);
 }
 
 } // namespace blink