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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 JavaScriptAudioNode_h
     26 #define JavaScriptAudioNode_h
     27 
     28 #include "ActiveDOMObject.h"
     29 #include "AudioNode.h"
     30 #include "EventListener.h"
     31 #include "EventTarget.h"
     32 #include <wtf/PassRefPtr.h>
     33 #include <wtf/RefPtr.h>
     34 #include <wtf/Vector.h>
     35 
     36 namespace WebCore {
     37 
     38 class AudioBuffer;
     39 class AudioContext;
     40 class AudioProcessingEvent;
     41 class Float32Array;
     42 
     43 // JavaScriptAudioNode is an AudioNode which allows for arbitrary synthesis or processing directly using JavaScript.
     44 // The API allows for a variable number of inputs and outputs, although it must have at least one input or output.
     45 // This basic implementation supports no more than one input and output.
     46 // The "onaudioprocess" attribute is an event listener which will get called periodically with an AudioProcessingEvent which has
     47 // AudioBuffers for each input and output.
     48 
     49 class JavaScriptAudioNode : public AudioNode, public EventTarget {
     50 public:
     51     // bufferSize must be one of the following values: 256, 512, 1024, 2048, 4096, 8192, 16384.
     52     // This value controls how frequently the onaudioprocess event handler is called and how many sample-frames need to be processed each call.
     53     // Lower numbers for bufferSize will result in a lower (better) latency. Higher numbers will be necessary to avoid audio breakup and glitches.
     54     // The value chosen must carefully balance between latency and audio quality.
     55     static PassRefPtr<JavaScriptAudioNode> create(AudioContext*, double sampleRate, size_t bufferSize, unsigned numberOfInputs = 1, unsigned numberOfOutputs = 1);
     56 
     57     virtual ~JavaScriptAudioNode();
     58 
     59     // AudioNode
     60     virtual void process(size_t framesToProcess);
     61     virtual void reset();
     62     virtual void initialize();
     63     virtual void uninitialize();
     64 
     65     // EventTarget
     66     virtual ScriptExecutionContext* scriptExecutionContext() const;
     67     virtual JavaScriptAudioNode* toJavaScriptAudioNode();
     68     virtual EventTargetData* eventTargetData() { return &m_eventTargetData; }
     69     virtual EventTargetData* ensureEventTargetData()  { return &m_eventTargetData; }
     70 
     71     size_t bufferSize() const { return m_bufferSize; }
     72 
     73     DEFINE_ATTRIBUTE_EVENT_LISTENER(audioprocess);
     74 
     75     // Reconcile ref/deref which are defined both in AudioNode and EventTarget.
     76     using AudioNode::ref;
     77     using AudioNode::deref;
     78 
     79 private:
     80     JavaScriptAudioNode(AudioContext*, double sampleRate, size_t bufferSize, unsigned numberOfInputs, unsigned numberOfOutputs);
     81 
     82     static void fireProcessEventDispatch(void* userData);
     83     void fireProcessEvent();
     84 
     85     // Double buffering
     86     unsigned doubleBufferIndex() const { return m_doubleBufferIndex; }
     87     void swapBuffers() { m_doubleBufferIndex = 1 - m_doubleBufferIndex; }
     88     unsigned m_doubleBufferIndex;
     89     unsigned m_doubleBufferIndexForEvent;
     90     Vector<RefPtr<AudioBuffer> > m_inputBuffers;
     91     Vector<RefPtr<AudioBuffer> > m_outputBuffers;
     92 
     93     virtual void refEventTarget() { ref(); }
     94     virtual void derefEventTarget() { deref(); }
     95     EventTargetData m_eventTargetData;
     96 
     97     size_t m_bufferSize;
     98     unsigned m_bufferReadWriteIndex;
     99     volatile bool m_isRequestOutstanding;
    100 };
    101 
    102 } // namespace WebCore
    103 
    104 #endif // JavaScriptAudioNode_h
    105