Source/modules/webaudio/AudioNode.h

/*
 * 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
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 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef AudioNode_h
#define AudioNode_h

#include "modules/EventTargetModules.h"
#include "platform/audio/AudioBus.h"
#include "wtf/Forward.h"
#include "wtf/OwnPtr.h"
#include "wtf/PassOwnPtr.h"
#include "wtf/RefPtr.h"
#include "wtf/Vector.h"

#define DEBUG_AUDIONODE_REFERENCES 0

namespace blink {

class AudioContext;
class AudioNodeInput;
class AudioNodeOutput;
class AudioParam;
class ExceptionState;

// An AudioNode is the basic building block for handling audio within an AudioContext.
// It may be an audio source, an intermediate processing module, or an audio destination.
// Each AudioNode can have inputs and/or outputs. An AudioSourceNode has no inputs and a single output.
// An AudioDestinationNode has one input and no outputs and represents the final destination to the audio hardware.
// Most processing nodes such as filters will have one input and one output, although multiple inputs and outputs are possible.

// AudioNode has its own ref-counting mechanism that use RefTypes so we cannot use RefCountedGarbageCollected.
class AudioNode : public NoBaseWillBeGarbageCollectedFinalized<AudioNode>, public EventTargetWithInlineData {
    WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(AudioNode);
public:
    enum { ProcessingSizeInFrames = 128 };

    AudioNode(AudioContext*, float sampleRate);
    virtual ~AudioNode();
    // dispose() is called just before the destructor. This must be called in
    // the main thread, and while the graph lock is held.
    virtual void dispose();
    static unsigned instanceCount() { return s_instanceCount; }

    AudioContext* context() { return m_context.get(); }
    const AudioContext* context() const { return m_context.get(); }

    enum NodeType {
        NodeTypeUnknown,
        NodeTypeDestination,
        NodeTypeOscillator,
        NodeTypeAudioBufferSource,
        NodeTypeMediaElementAudioSource,
        NodeTypeMediaStreamAudioDestination,
        NodeTypeMediaStreamAudioSource,
        NodeTypeJavaScript,
        NodeTypeBiquadFilter,
        NodeTypePanner,
        NodeTypeConvolver,
        NodeTypeDelay,
        NodeTypeGain,
        NodeTypeChannelSplitter,
        NodeTypeChannelMerger,
        NodeTypeAnalyser,
        NodeTypeDynamicsCompressor,
        NodeTypeWaveShaper,
        NodeTypeEnd
    };

    enum ChannelCountMode {
        Max,
        ClampedMax,
        Explicit
    };

    NodeType nodeType() const { return m_nodeType; }
    String nodeTypeName() const;
    void setNodeType(NodeType);

#if !ENABLE(OILPAN)
    // Can be called from main thread or context's audio thread.
    void ref();
    void deref();
#endif

    // This object has been connected to another object. This might have
    // existing connections from others.
    // This function must be called after acquiring a connection reference.
    void makeConnection();
    // This object will be disconnected from another object. This might have
    // remaining connections from others.
    // This function must be called before releasing a connection reference.
    void breakConnection();

    // Can be called from main thread or context's audio thread.  It must be called while the context's graph lock is held.
#if !ENABLE(OILPAN)
    void finishDeref();
#endif
    void breakConnectionWithLock();

    // The AudioNodeInput(s) (if any) will already have their input data available when process() is called.
    // Subclasses will take this input data and put the results in the AudioBus(s) of its AudioNodeOutput(s) (if any).
    // Called from context's audio thread.
    virtual void process(size_t framesToProcess) = 0;

    // No significant resources should be allocated until initialize() is called.
    // Processing may not occur until a node is initialized.
    virtual void initialize();
    virtual void uninitialize();

    bool isInitialized() const { return m_isInitialized; }

    unsigned numberOfInputs() const { return m_inputs.size(); }
    unsigned numberOfOutputs() const { return m_outputs.size(); }

    AudioNodeInput* input(unsigned);
    AudioNodeOutput* output(unsigned);

    // Called from main thread by corresponding JavaScript methods.
    virtual void connect(AudioNode*, unsigned outputIndex, unsigned inputIndex, ExceptionState&);
    void connect(AudioParam*, unsigned outputIndex, ExceptionState&);
    virtual void disconnect(unsigned outputIndex, ExceptionState&);

    virtual float sampleRate() const { return m_sampleRate; }

    // processIfNecessary() is called by our output(s) when the rendering graph needs this AudioNode to process.
    // This method ensures that the AudioNode will only process once per rendering time quantum even if it's called repeatedly.
    // This handles the case of "fanout" where an output is connected to multiple AudioNode inputs.
    // Called from context's audio thread.
    void processIfNecessary(size_t framesToProcess);

    // Called when a new connection has been made to one of our inputs or the connection number of channels has changed.
    // This potentially gives us enough information to perform a lazy initialization or, if necessary, a re-initialization.
    // Called from main thread.
    virtual void checkNumberOfChannelsForInput(AudioNodeInput*);

#if DEBUG_AUDIONODE_REFERENCES
    static void printNodeCounts();
#endif

    bool isDisposeCalled() const { return m_isDisposeCalled; }

    // tailTime() is the length of time (not counting latency time) where non-zero output may occur after continuous silent input.
    virtual double tailTime() const = 0;
    // latencyTime() is the length of time it takes for non-zero output to appear after non-zero input is provided. This only applies to
    // processing delay which is an artifact of the processing algorithm chosen and is *not* part of the intrinsic desired effect. For
    // example, a "delay" effect is expected to delay the signal, and thus would not be considered latency.
    virtual double latencyTime() const = 0;

    // propagatesSilence() should return true if the node will generate silent output when given silent input. By default, AudioNode
    // will take tailTime() and latencyTime() into account when determining whether the node will propagate silence.
    virtual bool propagatesSilence() const;
    bool inputsAreSilent();
    void silenceOutputs();
    void unsilenceOutputs();

    void enableOutputsIfNecessary();
    void disableOutputsIfNecessary();

    unsigned long channelCount();
    virtual void setChannelCount(unsigned long, ExceptionState&);

    String channelCountMode();
    void setChannelCountMode(const String&, ExceptionState&);

    String channelInterpretation();
    void setChannelInterpretation(const String&, ExceptionState&);

    ChannelCountMode internalChannelCountMode() const { return m_channelCountMode; }
    AudioBus::ChannelInterpretation internalChannelInterpretation() const { return m_channelInterpretation; }

    // EventTarget
    virtual const AtomicString& interfaceName() const OVERRIDE FINAL;
    virtual ExecutionContext* executionContext() const OVERRIDE FINAL;

    virtual void trace(Visitor*) OVERRIDE;

protected:
    // Inputs and outputs must be created before the AudioNode is initialized.
    void addInput();
    void addOutput(PassOwnPtrWillBeRawPtr<AudioNodeOutput>);

    // Called by processIfNecessary() to cause all parts of the rendering graph connected to us to process.
    // Each rendering quantum, the audio data for each of the AudioNode's inputs will be available after this method is called.
    // Called from context's audio thread.
    virtual void pullInputs(size_t framesToProcess);

    // Force all inputs to take any channel interpretation changes into account.
    void updateChannelsForInputs();

private:
    volatile bool m_isInitialized;
    NodeType m_nodeType;
    RefPtrWillBeMember<AudioContext> m_context;
    float m_sampleRate;
    WillBeHeapVector<OwnPtrWillBeMember<AudioNodeInput> > m_inputs;
    WillBeHeapVector<OwnPtrWillBeMember<AudioNodeOutput> > m_outputs;

    double m_lastProcessingTime;
    double m_lastNonSilentTime;

#if !ENABLE(OILPAN)
    // Ref-counting
    volatile int m_normalRefCount;
#endif
    volatile int m_connectionRefCount;

    bool m_isDisabled;
    bool m_isDisposeCalled;

#if DEBUG_AUDIONODE_REFERENCES
    static bool s_isNodeCountInitialized;
    static int s_nodeCount[NodeTypeEnd];
#endif
    static unsigned s_instanceCount;

#if !ENABLE(OILPAN)
    virtual void refEventTarget() OVERRIDE FINAL { ref(); }
    virtual void derefEventTarget() OVERRIDE FINAL { deref(); }
#endif

protected:
    unsigned m_channelCount;
    ChannelCountMode m_channelCountMode;
    AudioBus::ChannelInterpretation m_channelInterpretation;
};

} // namespace blink

#endif // AudioNode_h