Source/WebCore/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 <wtf/OwnPtr.h>
#include <wtf/PassOwnPtr.h>
#include <wtf/RefPtr.h>
#include <wtf/Vector.h>

#define DEBUG_AUDIONODE_REFERENCES 0

namespace WebCore {

class AudioContext;
class AudioNodeInput;
class AudioNodeOutput;

// 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.

class AudioNode {
public:
    enum { ProcessingSizeInFrames = 128 };

    AudioNode(AudioContext*, double sampleRate);
    virtual ~AudioNode();

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

    enum NodeType {
        NodeTypeUnknown,
        NodeTypeDestination,
        NodeTypeAudioBufferSource,
        NodeTypeJavaScript,
        NodeTypeLowPass2Filter,
        NodeTypeHighPass2Filter,
        NodeTypePanner,
        NodeTypeConvolver,
        NodeTypeDelay,
        NodeTypeGain,
        NodeTypeChannelSplitter,
        NodeTypeChannelMerger,
        NodeTypeAnalyser,
        NodeTypeEnd
    };

    NodeType type() const { return m_type; }
    void setType(NodeType);

    // We handle our own ref-counting because of the threading issues and subtle nature of
    // how AudioNodes can continue processing (playing one-shot sound) after there are no more
    // JavaScript references to the object.
    enum RefType { RefTypeNormal, RefTypeConnection, RefTypeDisabled };

    // Can be called from main thread or context's audio thread.
    void ref(RefType refType = RefTypeNormal);
    void deref(RefType refType = RefTypeNormal);

    // Can be called from main thread or context's audio thread.  It must be called while the context's graph lock is held.
    void finishDeref(RefType refType);

    // 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;

    // Resets DSP processing state (clears delay lines, filter memory, etc.)
    // Called from context's audio thread.
    virtual void reset() = 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; }
    void lazyInitialize();

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

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

    // connect() / disconnect() return true on success.
    // Called from main thread by corresponding JavaScript methods.
    bool connect(AudioNode* destination, unsigned outputIndex = 0, unsigned inputIndex = 0);
    bool disconnect(unsigned outputIndex = 0);

    double 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 isMarkedForDeletion() const { return m_isMarkedForDeletion; }

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

private:
    volatile bool m_isInitialized;
    NodeType m_type;
    RefPtr<AudioContext> m_context;
    double m_sampleRate;
    Vector<OwnPtr<AudioNodeInput> > m_inputs;
    Vector<OwnPtr<AudioNodeOutput> > m_outputs;

    double m_lastProcessingTime;

    // Ref-counting
    volatile int m_normalRefCount;
    volatile int m_connectionRefCount;
    volatile int m_disabledRefCount;
    
    bool m_isMarkedForDeletion;
    bool m_isDisabled;
    
#if DEBUG_AUDIONODE_REFERENCES
    static bool s_isNodeCountInitialized;
    static int s_nodeCount[NodeTypeEnd];
#endif
};

} // namespace WebCore

#endif // AudioNode_h