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      1 /*
      2  * Copyright (C) 2010, Google Inc. All rights reserved.
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions
      6  * are met:
      7  * 1.  Redistributions of source code must retain the above copyright
      8  *    notice, this list of conditions and the following disclaimer.
      9  * 2.  Redistributions in binary form must reproduce the above copyright
     10  *    notice, this list of conditions and the following disclaimer in the
     11  *    documentation and/or other materials provided with the distribution.
     12  *
     13  * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' AND ANY
     14  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
     15  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
     16  * DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY
     17  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
     18  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
     19  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
     20  * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     21  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
     22  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     23  */
     24 
     25 #ifndef AudioNode_h
     26 #define AudioNode_h
     27 
     28 #include "bindings/v8/ScriptWrappable.h"
     29 #include "core/events/EventTarget.h"
     30 #include "platform/audio/AudioBus.h"
     31 #include "wtf/Forward.h"
     32 #include "wtf/OwnPtr.h"
     33 #include "wtf/PassOwnPtr.h"
     34 #include "wtf/RefPtr.h"
     35 #include "wtf/Vector.h"
     36 
     37 #define DEBUG_AUDIONODE_REFERENCES 0
     38 
     39 namespace WebCore {
     40 
     41 class AudioContext;
     42 class AudioNodeInput;
     43 class AudioNodeOutput;
     44 class AudioParam;
     45 class ExceptionState;
     46 
     47 // An AudioNode is the basic building block for handling audio within an AudioContext.
     48 // It may be an audio source, an intermediate processing module, or an audio destination.
     49 // Each AudioNode can have inputs and/or outputs. An AudioSourceNode has no inputs and a single output.
     50 // An AudioDestinationNode has one input and no outputs and represents the final destination to the audio hardware.
     51 // Most processing nodes such as filters will have one input and one output, although multiple inputs and outputs are possible.
     52 
     53 class AudioNode : public ScriptWrappable, public EventTargetWithInlineData {
     54 public:
     55     enum { ProcessingSizeInFrames = 128 };
     56 
     57     AudioNode(AudioContext*, float sampleRate);
     58     virtual ~AudioNode();
     59 
     60     AudioContext* context() { return m_context.get(); }
     61     const AudioContext* context() const { return m_context.get(); }
     62 
     63     enum NodeType {
     64         NodeTypeUnknown,
     65         NodeTypeDestination,
     66         NodeTypeOscillator,
     67         NodeTypeAudioBufferSource,
     68         NodeTypeMediaElementAudioSource,
     69         NodeTypeMediaStreamAudioDestination,
     70         NodeTypeMediaStreamAudioSource,
     71         NodeTypeJavaScript,
     72         NodeTypeBiquadFilter,
     73         NodeTypePanner,
     74         NodeTypeConvolver,
     75         NodeTypeDelay,
     76         NodeTypeGain,
     77         NodeTypeChannelSplitter,
     78         NodeTypeChannelMerger,
     79         NodeTypeAnalyser,
     80         NodeTypeDynamicsCompressor,
     81         NodeTypeWaveShaper,
     82         NodeTypeEnd
     83     };
     84 
     85     enum ChannelCountMode {
     86         Max,
     87         ClampedMax,
     88         Explicit
     89     };
     90 
     91     NodeType nodeType() const { return m_nodeType; }
     92     String nodeTypeName() const;
     93     void setNodeType(NodeType);
     94 
     95     // We handle our own ref-counting because of the threading issues and subtle nature of
     96     // how AudioNodes can continue processing (playing one-shot sound) after there are no more
     97     // JavaScript references to the object.
     98     enum RefType { RefTypeNormal, RefTypeConnection };
     99 
    100     // Can be called from main thread or context's audio thread.
    101     void ref(RefType refType = RefTypeNormal);
    102     void deref(RefType refType = RefTypeNormal);
    103 
    104     // Can be called from main thread or context's audio thread.  It must be called while the context's graph lock is held.
    105     void finishDeref(RefType refType);
    106 
    107     // The AudioNodeInput(s) (if any) will already have their input data available when process() is called.
    108     // Subclasses will take this input data and put the results in the AudioBus(s) of its AudioNodeOutput(s) (if any).
    109     // Called from context's audio thread.
    110     virtual void process(size_t framesToProcess) = 0;
    111 
    112     // Resets DSP processing state (clears delay lines, filter memory, etc.)
    113     // Called from context's audio thread.
    114     virtual void reset() = 0;
    115 
    116     // No significant resources should be allocated until initialize() is called.
    117     // Processing may not occur until a node is initialized.
    118     virtual void initialize();
    119     virtual void uninitialize();
    120 
    121     bool isInitialized() const { return m_isInitialized; }
    122     void lazyInitialize();
    123 
    124     unsigned numberOfInputs() const { return m_inputs.size(); }
    125     unsigned numberOfOutputs() const { return m_outputs.size(); }
    126 
    127     AudioNodeInput* input(unsigned);
    128     AudioNodeOutput* output(unsigned);
    129 
    130     // Called from main thread by corresponding JavaScript methods.
    131     virtual void connect(AudioNode*, unsigned outputIndex, unsigned inputIndex, ExceptionState&);
    132     void connect(AudioParam*, unsigned outputIndex, ExceptionState&);
    133     virtual void disconnect(unsigned outputIndex, ExceptionState&);
    134 
    135     virtual float sampleRate() const { return m_sampleRate; }
    136 
    137     // processIfNecessary() is called by our output(s) when the rendering graph needs this AudioNode to process.
    138     // This method ensures that the AudioNode will only process once per rendering time quantum even if it's called repeatedly.
    139     // This handles the case of "fanout" where an output is connected to multiple AudioNode inputs.
    140     // Called from context's audio thread.
    141     void processIfNecessary(size_t framesToProcess);
    142 
    143     // Called when a new connection has been made to one of our inputs or the connection number of channels has changed.
    144     // This potentially gives us enough information to perform a lazy initialization or, if necessary, a re-initialization.
    145     // Called from main thread.
    146     virtual void checkNumberOfChannelsForInput(AudioNodeInput*);
    147 
    148 #if DEBUG_AUDIONODE_REFERENCES
    149     static void printNodeCounts();
    150 #endif
    151 
    152     bool isMarkedForDeletion() const { return m_isMarkedForDeletion; }
    153 
    154     // tailTime() is the length of time (not counting latency time) where non-zero output may occur after continuous silent input.
    155     virtual double tailTime() const = 0;
    156     // latencyTime() is the length of time it takes for non-zero output to appear after non-zero input is provided. This only applies to
    157     // processing delay which is an artifact of the processing algorithm chosen and is *not* part of the intrinsic desired effect. For
    158     // example, a "delay" effect is expected to delay the signal, and thus would not be considered latency.
    159     virtual double latencyTime() const = 0;
    160 
    161     // propagatesSilence() should return true if the node will generate silent output when given silent input. By default, AudioNode
    162     // will take tailTime() and latencyTime() into account when determining whether the node will propagate silence.
    163     virtual bool propagatesSilence() const;
    164     bool inputsAreSilent();
    165     void silenceOutputs();
    166     void unsilenceOutputs();
    167 
    168     void enableOutputsIfNecessary();
    169     void disableOutputsIfNecessary();
    170 
    171     unsigned long channelCount();
    172     virtual void setChannelCount(unsigned long, ExceptionState&);
    173 
    174     String channelCountMode();
    175     void setChannelCountMode(const String&, ExceptionState&);
    176 
    177     String channelInterpretation();
    178     void setChannelInterpretation(const String&, ExceptionState&);
    179 
    180     ChannelCountMode internalChannelCountMode() const { return m_channelCountMode; }
    181     AudioBus::ChannelInterpretation internalChannelInterpretation() const { return m_channelInterpretation; }
    182 
    183     // EventTarget
    184     virtual const AtomicString& interfaceName() const OVERRIDE;
    185     virtual ExecutionContext* executionContext() const OVERRIDE;
    186 
    187 protected:
    188     // Inputs and outputs must be created before the AudioNode is initialized.
    189     void addInput(PassOwnPtr<AudioNodeInput>);
    190     void addOutput(PassOwnPtr<AudioNodeOutput>);
    191 
    192     // Called by processIfNecessary() to cause all parts of the rendering graph connected to us to process.
    193     // Each rendering quantum, the audio data for each of the AudioNode's inputs will be available after this method is called.
    194     // Called from context's audio thread.
    195     virtual void pullInputs(size_t framesToProcess);
    196 
    197     // Force all inputs to take any channel interpretation changes into account.
    198     void updateChannelsForInputs();
    199 
    200 private:
    201     volatile bool m_isInitialized;
    202     NodeType m_nodeType;
    203     RefPtr<AudioContext> m_context;
    204     float m_sampleRate;
    205     Vector<OwnPtr<AudioNodeInput> > m_inputs;
    206     Vector<OwnPtr<AudioNodeOutput> > m_outputs;
    207 
    208     double m_lastProcessingTime;
    209     double m_lastNonSilentTime;
    210 
    211     // Ref-counting
    212     volatile int m_normalRefCount;
    213     volatile int m_connectionRefCount;
    214 
    215     bool m_isMarkedForDeletion;
    216     bool m_isDisabled;
    217 
    218 #if DEBUG_AUDIONODE_REFERENCES
    219     static bool s_isNodeCountInitialized;
    220     static int s_nodeCount[NodeTypeEnd];
    221 #endif
    222 
    223     virtual void refEventTarget() OVERRIDE { ref(); }
    224     virtual void derefEventTarget() OVERRIDE { deref(); }
    225 
    226 protected:
    227     unsigned m_channelCount;
    228     ChannelCountMode m_channelCountMode;
    229     AudioBus::ChannelInterpretation m_channelInterpretation;
    230 };
    231 
    232 } // namespace WebCore
    233 
    234 #endif // AudioNode_h
    235