Continue to process AnalyserNode if inputs are silent.

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

 /*
  * Copyright (C) 2010, 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 32 matching lines @@
   return adoptRef(new AnalyserHandler(node, sampleRate));
 }
 
 AnalyserHandler::~AnalyserHandler() {
   uninitialize();
 }
 
 void AnalyserHandler::process(size_t framesToProcess) {
   AudioBus* outputBus = output(0).bus();
 
-  if (!isInitialized() || !input(0).isConnected()) {
+  if (!isInitialized()) {
     outputBus->zero();
     return;
   }
 
   AudioBus* inputBus = input(0).bus();
 
-  // Give the analyser the audio which is passing through this AudioNode.
+  // Give the analyser the audio which is passing through this
+  // AudioNode.  This must always be done so that the state of the
+  // Analyser reflects the current input.
   m_analyser.writeInput(inputBus, framesToProcess);
 
+  if (!input(0).isConnected()) {
+    // No inputs, so clear the output, and propagate the silence hint.
+    outputBus->zero();
+    return;
+  }
+
   // For in-place processing, our override of pullInputs() will just pass the
   // audio data through unchanged if the channel count matches from input to
   // output (resulting in inputBus == outputBus). Otherwise, do an up-mix to
   // stereo.
   if (inputBus != outputBus)
     outputBus->copyFrom(*inputBus);
 }
 
 void AnalyserHandler::setFftSize(unsigned size,
                                  ExceptionState& exceptionState) {
@@ skipping 52 matching lines @@
     m_analyser.setSmoothingTimeConstant(k);
   } else {
     exceptionState.throwDOMException(
         IndexSizeError,
         ExceptionMessages::indexOutsideRange(
             "smoothing value", k, 0.0, ExceptionMessages::InclusiveBound, 1.0,
             ExceptionMessages::InclusiveBound));
   }
 }
 
+void AnalyserHandler::updatePullStatus() {
+#if DCHECK_IS_ON()
+  DCHECK(context()->isGraphOwner());
+#endif
+
+  if (output(0).isConnected()) {
+    // When an AudioBasicInspectorNode is connected to a downstream node, it
+    // will get pulled by the downstream node, thus remove it from the context's
+    // automatic pull list.
+    if (m_needAutomaticPull) {
+      context()->deferredTaskHandler().removeAutomaticPullNode(this);
+      m_needAutomaticPull = false;
+    }
+  } else {
+    unsigned numberOfInputConnections = input(0).numberOfRenderingConnections();
+    // When an AnalyserNode is not connected to any downstream node
+    // while still connected from upstream node(s), add it to the context's
+    // automatic pull list.
+    //
+    // But don't remove the AnalyserNode if there are no inputs
+    // connected to the node.  The node needs to be pulled so that the
+    // internal state is updated with the correct input signal (of
+    // zeroes).
+    if (numberOfInputConnections && !m_needAutomaticPull) {
+      context()->deferredTaskHandler().addAutomaticPullNode(this);
+      m_needAutomaticPull = true;
+    }
+  }
+}
 // ----------------------------------------------------------------
 
 AnalyserNode::AnalyserNode(BaseAudioContext& context)
     : AudioBasicInspectorNode(context) {
   setHandler(AnalyserHandler::create(*this, context.sampleRate()));
 }
 
 AnalyserNode* AnalyserNode::create(BaseAudioContext& context,
                                    ExceptionState& exceptionState) {
   DCHECK(isMainThread());
@@ skipping 90 matching lines @@
 
 void AnalyserNode::getFloatTimeDomainData(DOMFloat32Array* array) {
   analyserHandler().getFloatTimeDomainData(array);
 }
 
 void AnalyserNode::getByteTimeDomainData(DOMUint8Array* array) {
   analyserHandler().getByteTimeDomainData(array);
 }
 
 }  // namespace blink