Source/WebCore/Modules/webaudio/PannerNode.cpp - WebKit - Git at Google

 /*
  * 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
  *    documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' AND ANY
  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  * DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY
  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
  * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */

 #include "config.h"
 #include "PannerNode.h"

 #if ENABLE(WEB_AUDIO)

 #include "AudioBufferSourceNode.h"
 #include "AudioBus.h"
 #include "AudioContext.h"
 #include "AudioNodeInput.h"
 #include "AudioNodeOutput.h"
 #include "HRTFPanner.h"
 #include "ScriptExecutionContext.h"
 #include <wtf/IsoMallocInlines.h>
 #include <wtf/MathExtras.h>

 namespace WebCore {

 WTF_MAKE_ISO_ALLOCATED_IMPL(PannerNode);

 static void fixNANs(double &x)
 {
     if (std::isnan(x) || std::isinf(x))
         x = 0.0;
 }

 PannerNode::PannerNode(AudioContext& context, float sampleRate)
     : AudioNode(context, sampleRate)
     , m_panningModel(PanningModelType::HRTF)
     , m_lastGain(-1.0)
     , m_connectionCount(0)
 {
     setNodeType(NodeTypePanner);

     // Load the HRTF database asynchronously so we don't block the Javascript thread while creating the HRTF database.
     m_hrtfDatabaseLoader = HRTFDatabaseLoader::createAndLoadAsynchronouslyIfNecessary(context.sampleRate());

     addInput(std::make_unique<AudioNodeInput>(this));
     addOutput(std::make_unique<AudioNodeOutput>(this, 2));

     // Node-specific default mixing rules.
     m_channelCount = 2;
     m_channelCountMode = ClampedMax;
     m_channelInterpretation = AudioBus::Speakers;

     m_distanceGain = AudioParam::create(context, "distanceGain", 1.0, 0.0, 1.0);
     m_coneGain = AudioParam::create(context, "coneGain", 1.0, 0.0, 1.0);

     m_position = FloatPoint3D(0, 0, 0);
     m_orientation = FloatPoint3D(1, 0, 0);
     m_velocity = FloatPoint3D(0, 0, 0);

     initialize();
 }

 PannerNode::~PannerNode()
 {
     uninitialize();
 }

 void PannerNode::pullInputs(size_t framesToProcess)
 {
     // We override pullInputs(), so we can detect new AudioSourceNodes which have connected to us when new connections are made.
     // These AudioSourceNodes need to be made aware of our existence in order to handle doppler shift pitch changes.
     if (m_connectionCount != context().connectionCount()) {
         m_connectionCount = context().connectionCount();

         // Recursively go through all nodes connected to us.
         HashSet<AudioNode*> visitedNodes;
         notifyAudioSourcesConnectedToNode(this, visitedNodes);
     }

     AudioNode::pullInputs(framesToProcess);
 }

 void PannerNode::process(size_t framesToProcess)
 {
     AudioBus* destination = output(0)->bus();

     if (!isInitialized() || !input(0)->isConnected() || !m_panner.get()) {
         destination->zero();
         return;
     }

     AudioBus* source = input(0)->bus();
     if (!source) {
         destination->zero();
         return;
     }

     // HRTFDatabase should be loaded before proceeding for offline audio context when panningModel() is "HRTF".
     if (panningModel() == PanningModelType::HRTF && !m_hrtfDatabaseLoader->isLoaded()) {
         if (context().isOfflineContext())
             m_hrtfDatabaseLoader->waitForLoaderThreadCompletion();
         else {
             destination->zero();
             return;
         }
     }

     // The audio thread can't block on this lock, so we use std::try_to_lock instead.
     std::unique_lock<Lock> lock(m_pannerMutex, std::try_to_lock);
     if (!lock.owns_lock()) {
         // Too bad - The try_lock() failed. We must be in the middle of changing the panner.
         destination->zero();
         return;
     }

     // Apply the panning effect.
     double azimuth;
     double elevation;
     getAzimuthElevation(&azimuth, &elevation);
     m_panner->pan(azimuth, elevation, source, destination, framesToProcess);

     // Get the distance and cone gain.
     double totalGain = distanceConeGain();

     // Snap to desired gain at the beginning.
     if (m_lastGain == -1.0)
         m_lastGain = totalGain;

     // Apply gain in-place with de-zippering.
     destination->copyWithGainFrom(*destination, &m_lastGain, totalGain);
 }

 void PannerNode::reset()
 {
     m_lastGain = -1.0; // force to snap to initial gain
     if (m_panner.get())
         m_panner->reset();
 }

 void PannerNode::initialize()
 {
     if (isInitialized())
         return;

     m_panner = Panner::create(m_panningModel, sampleRate(), m_hrtfDatabaseLoader.get());

     AudioNode::initialize();
 }

 void PannerNode::uninitialize()
 {
     if (!isInitialized())
         return;

     m_panner = nullptr;
     AudioNode::uninitialize();
 }

 AudioListener* PannerNode::listener()
 {
     return context().listener();
 }

 void PannerNode::setPanningModel(PanningModelType model)
 {
     if (!m_panner.get() || model != m_panningModel) {
         // This synchronizes with process().
         std::lock_guard<Lock> lock(m_pannerMutex);

         m_panner = Panner::create(model, sampleRate(), m_hrtfDatabaseLoader.get());
         m_panningModel = model;
     }
 }

 DistanceModelType PannerNode::distanceModel() const
 {
     return const_cast<PannerNode*>(this)->m_distanceEffect.model();
 }

 void PannerNode::setDistanceModel(DistanceModelType model)
 {
     m_distanceEffect.setModel(model, true);
 }

 void PannerNode::getAzimuthElevation(double* outAzimuth, double* outElevation)
 {
     // FIXME: we should cache azimuth and elevation (if possible), so we only re-calculate if a change has been made.

     double azimuth = 0.0;

     // Calculate the source-listener vector
     FloatPoint3D listenerPosition = listener()->position();
     FloatPoint3D sourceListener = m_position - listenerPosition;

     if (sourceListener.isZero()) {
         // degenerate case if source and listener are at the same point
         *outAzimuth = 0.0;
         *outElevation = 0.0;
         return;
     }

     sourceListener.normalize();

     // Align axes
     FloatPoint3D listenerFront = listener()->orientation();
     FloatPoint3D listenerUp = listener()->upVector();
     FloatPoint3D listenerRight = listenerFront.cross(listenerUp);
     listenerRight.normalize();

     FloatPoint3D listenerFrontNorm = listenerFront;
     listenerFrontNorm.normalize();

     FloatPoint3D up = listenerRight.cross(listenerFrontNorm);

     float upProjection = sourceListener.dot(up);

     FloatPoint3D projectedSource = sourceListener - upProjection * up;
     projectedSource.normalize();

     azimuth = 180.0 * acos(projectedSource.dot(listenerRight)) / piDouble;
     fixNANs(azimuth); // avoid illegal values

     // Source  in front or behind the listener
     double frontBack = projectedSource.dot(listenerFrontNorm);
     if (frontBack < 0.0)
         azimuth = 360.0 - azimuth;

     // Make azimuth relative to "front" and not "right" listener vector
     if ((azimuth >= 0.0) && (azimuth <= 270.0))
         azimuth = 90.0 - azimuth;
     else
         azimuth = 450.0 - azimuth;

     // Elevation
     double elevation = 90.0 - 180.0 * acos(sourceListener.dot(up)) / piDouble;
     fixNANs(elevation); // avoid illegal values

     if (elevation > 90.0)
         elevation = 180.0 - elevation;
     else if (elevation < -90.0)
         elevation = -180.0 - elevation;

     if (outAzimuth)
         *outAzimuth = azimuth;
     if (outElevation)
         *outElevation = elevation;
 }

 float PannerNode::dopplerRate()
 {
     double dopplerShift = 1.0;

     // FIXME: optimize for case when neither source nor listener has changed...
     double dopplerFactor = listener()->dopplerFactor();

     if (dopplerFactor > 0.0) {
         double speedOfSound = listener()->speedOfSound();

         const FloatPoint3D &sourceVelocity = m_velocity;
         const FloatPoint3D &listenerVelocity = listener()->velocity();

         // Don't bother if both source and listener have no velocity
         bool sourceHasVelocity = !sourceVelocity.isZero();
         bool listenerHasVelocity = !listenerVelocity.isZero();

         if (sourceHasVelocity || listenerHasVelocity) {
             // Calculate the source to listener vector
             FloatPoint3D listenerPosition = listener()->position();
             FloatPoint3D sourceToListener = m_position - listenerPosition;

             double sourceListenerMagnitude = sourceToListener.length();

             double listenerProjection = sourceToListener.dot(listenerVelocity) / sourceListenerMagnitude;
             double sourceProjection = sourceToListener.dot(sourceVelocity) / sourceListenerMagnitude;

             listenerProjection = -listenerProjection;
             sourceProjection = -sourceProjection;

             double scaledSpeedOfSound = speedOfSound / dopplerFactor;
             listenerProjection = std::min(listenerProjection, scaledSpeedOfSound);
             sourceProjection = std::min(sourceProjection, scaledSpeedOfSound);

             dopplerShift = ((speedOfSound - dopplerFactor * listenerProjection) / (speedOfSound - dopplerFactor * sourceProjection));
             fixNANs(dopplerShift); // avoid illegal values

             // Limit the pitch shifting to 4 octaves up and 3 octaves down.
             if (dopplerShift > 16.0)
                 dopplerShift = 16.0;
             else if (dopplerShift < 0.125)
                 dopplerShift = 0.125;
         }
     }

     return static_cast<float>(dopplerShift);
 }

 float PannerNode::distanceConeGain()
 {
     FloatPoint3D listenerPosition = listener()->position();

     double listenerDistance = m_position.distanceTo(listenerPosition);
     double distanceGain = m_distanceEffect.gain(listenerDistance);

     m_distanceGain->setValue(static_cast<float>(distanceGain));

     // FIXME: could optimize by caching coneGain
     double coneGain = m_coneEffect.gain(m_position, m_orientation, listenerPosition);

     m_coneGain->setValue(static_cast<float>(coneGain));

     return float(distanceGain * coneGain);
 }

 void PannerNode::notifyAudioSourcesConnectedToNode(AudioNode* node, HashSet<AudioNode*>& visitedNodes)
 {
     ASSERT(node);
     if (!node)
         return;

     // First check if this node is an AudioBufferSourceNode. If so, let it know about us so that doppler shift pitch can be taken into account.
     if (node->nodeType() == NodeTypeAudioBufferSource) {
         AudioBufferSourceNode* bufferSourceNode = reinterpret_cast<AudioBufferSourceNode*>(node);
         bufferSourceNode->setPannerNode(this);
     } else {
         // Go through all inputs to this node.
         for (unsigned i = 0; i < node->numberOfInputs(); ++i) {
             AudioNodeInput* input = node->input(i);

             // For each input, go through all of its connections, looking for AudioBufferSourceNodes.
             for (unsigned j = 0; j < input->numberOfRenderingConnections(); ++j) {
                 AudioNodeOutput* connectedOutput = input->renderingOutput(j);
                 AudioNode* connectedNode = connectedOutput->node();
                 if (visitedNodes.contains(connectedNode))
                     continue;

                 visitedNodes.add(connectedNode);
                 notifyAudioSourcesConnectedToNode(connectedNode, visitedNodes);
             }
         }
     }
 }

 } // namespace WebCore

 #endif // ENABLE(WEB_AUDIO)
	/*
	* 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
	* documentation and/or other materials provided with the distribution.
	*
	* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' AND ANY
	* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
	* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
	* DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY
	* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
	* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
	* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
	* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
	* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*/

	#include "config.h"
	#include "PannerNode.h"

	#if ENABLE(WEB_AUDIO)

	#include "AudioBufferSourceNode.h"
	#include "AudioBus.h"
	#include "AudioContext.h"
	#include "AudioNodeInput.h"
	#include "AudioNodeOutput.h"
	#include "HRTFPanner.h"
	#include "ScriptExecutionContext.h"
	#include <wtf/IsoMallocInlines.h>
	#include <wtf/MathExtras.h>

	namespace WebCore {

	WTF_MAKE_ISO_ALLOCATED_IMPL(PannerNode);

	static void fixNANs(double &x)
	{
	if (std::isnan(x) \|\| std::isinf(x))
	x = 0.0;
	}

	PannerNode::PannerNode(AudioContext& context, float sampleRate)
	: AudioNode(context, sampleRate)
	, m_panningModel(PanningModelType::HRTF)
	, m_lastGain(-1.0)
	, m_connectionCount(0)
	{
	setNodeType(NodeTypePanner);

	// Load the HRTF database asynchronously so we don't block the Javascript thread while creating the HRTF database.
	m_hrtfDatabaseLoader = HRTFDatabaseLoader::createAndLoadAsynchronouslyIfNecessary(context.sampleRate());

	addInput(std::make_unique<AudioNodeInput>(this));
	addOutput(std::make_unique<AudioNodeOutput>(this, 2));

	// Node-specific default mixing rules.
	m_channelCount = 2;
	m_channelCountMode = ClampedMax;
	m_channelInterpretation = AudioBus::Speakers;

	m_distanceGain = AudioParam::create(context, "distanceGain", 1.0, 0.0, 1.0);
	m_coneGain = AudioParam::create(context, "coneGain", 1.0, 0.0, 1.0);

	m_position = FloatPoint3D(0, 0, 0);
	m_orientation = FloatPoint3D(1, 0, 0);
	m_velocity = FloatPoint3D(0, 0, 0);

	initialize();
	}

	PannerNode::~PannerNode()
	{
	uninitialize();
	}

	void PannerNode::pullInputs(size_t framesToProcess)
	{
	// We override pullInputs(), so we can detect new AudioSourceNodes which have connected to us when new connections are made.
	// These AudioSourceNodes need to be made aware of our existence in order to handle doppler shift pitch changes.
	if (m_connectionCount != context().connectionCount()) {
	m_connectionCount = context().connectionCount();

	// Recursively go through all nodes connected to us.
	HashSet<AudioNode*> visitedNodes;
	notifyAudioSourcesConnectedToNode(this, visitedNodes);
	}

	AudioNode::pullInputs(framesToProcess);
	}

	void PannerNode::process(size_t framesToProcess)
	{
	AudioBus* destination = output(0)->bus();

	if (!isInitialized() \|\| !input(0)->isConnected() \|\| !m_panner.get()) {
	destination->zero();
	return;
	}

	AudioBus* source = input(0)->bus();
	if (!source) {
	destination->zero();
	return;
	}

	// HRTFDatabase should be loaded before proceeding for offline audio context when panningModel() is "HRTF".
	if (panningModel() == PanningModelType::HRTF && !m_hrtfDatabaseLoader->isLoaded()) {
	if (context().isOfflineContext())
	m_hrtfDatabaseLoader->waitForLoaderThreadCompletion();
	else {
	destination->zero();
	return;
	}
	}

	// The audio thread can't block on this lock, so we use std::try_to_lock instead.
	std::unique_lock<Lock> lock(m_pannerMutex, std::try_to_lock);
	if (!lock.owns_lock()) {
	// Too bad - The try_lock() failed. We must be in the middle of changing the panner.
	destination->zero();
	return;
	}

	// Apply the panning effect.
	double azimuth;
	double elevation;
	getAzimuthElevation(&azimuth, &elevation);
	m_panner->pan(azimuth, elevation, source, destination, framesToProcess);

	// Get the distance and cone gain.
	double totalGain = distanceConeGain();

	// Snap to desired gain at the beginning.
	if (m_lastGain == -1.0)
	m_lastGain = totalGain;

	// Apply gain in-place with de-zippering.
	destination->copyWithGainFrom(*destination, &m_lastGain, totalGain);
	}

	void PannerNode::reset()
	{
	m_lastGain = -1.0; // force to snap to initial gain
	if (m_panner.get())
	m_panner->reset();
	}

	void PannerNode::initialize()
	{
	if (isInitialized())
	return;

	m_panner = Panner::create(m_panningModel, sampleRate(), m_hrtfDatabaseLoader.get());

	AudioNode::initialize();
	}

	void PannerNode::uninitialize()
	{
	if (!isInitialized())
	return;

	m_panner = nullptr;
	AudioNode::uninitialize();
	}

	AudioListener* PannerNode::listener()
	{
	return context().listener();
	}

	void PannerNode::setPanningModel(PanningModelType model)
	{
	if (!m_panner.get() \|\| model != m_panningModel) {
	// This synchronizes with process().
	std::lock_guard<Lock> lock(m_pannerMutex);

	m_panner = Panner::create(model, sampleRate(), m_hrtfDatabaseLoader.get());
	m_panningModel = model;
	}
	}

	DistanceModelType PannerNode::distanceModel() const
	{
	return const_cast<PannerNode*>(this)->m_distanceEffect.model();
	}

	void PannerNode::setDistanceModel(DistanceModelType model)
	{
	m_distanceEffect.setModel(model, true);
	}

	void PannerNode::getAzimuthElevation(double* outAzimuth, double* outElevation)
	{
	// FIXME: we should cache azimuth and elevation (if possible), so we only re-calculate if a change has been made.

	double azimuth = 0.0;

	// Calculate the source-listener vector
	FloatPoint3D listenerPosition = listener()->position();
	FloatPoint3D sourceListener = m_position - listenerPosition;

	if (sourceListener.isZero()) {
	// degenerate case if source and listener are at the same point
	*outAzimuth = 0.0;
	*outElevation = 0.0;
	return;
	}

	sourceListener.normalize();

	// Align axes
	FloatPoint3D listenerFront = listener()->orientation();
	FloatPoint3D listenerUp = listener()->upVector();
	FloatPoint3D listenerRight = listenerFront.cross(listenerUp);
	listenerRight.normalize();

	FloatPoint3D listenerFrontNorm = listenerFront;
	listenerFrontNorm.normalize();

	FloatPoint3D up = listenerRight.cross(listenerFrontNorm);

	float upProjection = sourceListener.dot(up);

	FloatPoint3D projectedSource = sourceListener - upProjection * up;
	projectedSource.normalize();

	azimuth = 180.0 * acos(projectedSource.dot(listenerRight)) / piDouble;
	fixNANs(azimuth); // avoid illegal values

	// Source in front or behind the listener
	double frontBack = projectedSource.dot(listenerFrontNorm);
	if (frontBack < 0.0)
	azimuth = 360.0 - azimuth;

	// Make azimuth relative to "front" and not "right" listener vector
	if ((azimuth >= 0.0) && (azimuth <= 270.0))
	azimuth = 90.0 - azimuth;
	else
	azimuth = 450.0 - azimuth;

	// Elevation
	double elevation = 90.0 - 180.0 * acos(sourceListener.dot(up)) / piDouble;
	fixNANs(elevation); // avoid illegal values

	if (elevation > 90.0)
	elevation = 180.0 - elevation;
	else if (elevation < -90.0)
	elevation = -180.0 - elevation;

	if (outAzimuth)
	*outAzimuth = azimuth;
	if (outElevation)
	*outElevation = elevation;
	}

	float PannerNode::dopplerRate()
	{
	double dopplerShift = 1.0;

	// FIXME: optimize for case when neither source nor listener has changed...
	double dopplerFactor = listener()->dopplerFactor();

	if (dopplerFactor > 0.0) {
	double speedOfSound = listener()->speedOfSound();

	const FloatPoint3D &sourceVelocity = m_velocity;
	const FloatPoint3D &listenerVelocity = listener()->velocity();

	// Don't bother if both source and listener have no velocity
	bool sourceHasVelocity = !sourceVelocity.isZero();
	bool listenerHasVelocity = !listenerVelocity.isZero();

	if (sourceHasVelocity \|\| listenerHasVelocity) {
	// Calculate the source to listener vector
	FloatPoint3D listenerPosition = listener()->position();
	FloatPoint3D sourceToListener = m_position - listenerPosition;

	double sourceListenerMagnitude = sourceToListener.length();

	double listenerProjection = sourceToListener.dot(listenerVelocity) / sourceListenerMagnitude;
	double sourceProjection = sourceToListener.dot(sourceVelocity) / sourceListenerMagnitude;

	listenerProjection = -listenerProjection;
	sourceProjection = -sourceProjection;

	double scaledSpeedOfSound = speedOfSound / dopplerFactor;
	listenerProjection = std::min(listenerProjection, scaledSpeedOfSound);
	sourceProjection = std::min(sourceProjection, scaledSpeedOfSound);

	dopplerShift = ((speedOfSound - dopplerFactor * listenerProjection) / (speedOfSound - dopplerFactor * sourceProjection));
	fixNANs(dopplerShift); // avoid illegal values

	// Limit the pitch shifting to 4 octaves up and 3 octaves down.
	if (dopplerShift > 16.0)
	dopplerShift = 16.0;
	else if (dopplerShift < 0.125)
	dopplerShift = 0.125;
	}
	}

	return static_cast<float>(dopplerShift);
	}

	float PannerNode::distanceConeGain()
	{
	FloatPoint3D listenerPosition = listener()->position();

	double listenerDistance = m_position.distanceTo(listenerPosition);
	double distanceGain = m_distanceEffect.gain(listenerDistance);

	m_distanceGain->setValue(static_cast<float>(distanceGain));

	// FIXME: could optimize by caching coneGain
	double coneGain = m_coneEffect.gain(m_position, m_orientation, listenerPosition);

	m_coneGain->setValue(static_cast<float>(coneGain));

	return float(distanceGain * coneGain);
	}

	void PannerNode::notifyAudioSourcesConnectedToNode(AudioNode* node, HashSet<AudioNode*>& visitedNodes)
	{
	ASSERT(node);
	if (!node)
	return;

	// First check if this node is an AudioBufferSourceNode. If so, let it know about us so that doppler shift pitch can be taken into account.
	if (node->nodeType() == NodeTypeAudioBufferSource) {
	AudioBufferSourceNode* bufferSourceNode = reinterpret_cast<AudioBufferSourceNode*>(node);
	bufferSourceNode->setPannerNode(this);
	} else {
	// Go through all inputs to this node.
	for (unsigned i = 0; i < node->numberOfInputs(); ++i) {
	AudioNodeInput* input = node->input(i);

	// For each input, go through all of its connections, looking for AudioBufferSourceNodes.
	for (unsigned j = 0; j < input->numberOfRenderingConnections(); ++j) {
	AudioNodeOutput* connectedOutput = input->renderingOutput(j);
	AudioNode* connectedNode = connectedOutput->node();
	if (visitedNodes.contains(connectedNode))
	continue;

	visitedNodes.add(connectedNode);
	notifyAudioSourcesConnectedToNode(connectedNode, visitedNodes);
	}
	}
	}
	}

	} // namespace WebCore

	#endif // ENABLE(WEB_AUDIO)