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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 #include "config.h"
     26 
     27 #if ENABLE(WEB_AUDIO)
     28 
     29 #include "AudioDestinationNode.h"
     30 
     31 #include "AudioBus.h"
     32 #include "AudioContext.h"
     33 #include "AudioNodeInput.h"
     34 #include "AudioNodeOutput.h"
     35 
     36 namespace WebCore {
     37 
     38 AudioDestinationNode::AudioDestinationNode(AudioContext* context, double sampleRate)
     39     : AudioNode(context, sampleRate)
     40     , m_currentTime(0.0)
     41 {
     42     addInput(adoptPtr(new AudioNodeInput(this)));
     43 
     44     setType(NodeTypeDestination);
     45 }
     46 
     47 AudioDestinationNode::~AudioDestinationNode()
     48 {
     49     uninitialize();
     50 }
     51 
     52 // The audio hardware calls us back here to gets its input stream.
     53 void AudioDestinationNode::provideInput(AudioBus* destinationBus, size_t numberOfFrames)
     54 {
     55     context()->setAudioThread(currentThread());
     56 
     57     if (!context()->isRunnable()) {
     58         destinationBus->zero();
     59         return;
     60     }
     61 
     62     // Let the context take care of any business at the start of each render quantum.
     63     context()->handlePreRenderTasks();
     64 
     65     // This will cause the node(s) connected to us to process, which in turn will pull on their input(s),
     66     // all the way backwards through the rendering graph.
     67     AudioBus* renderedBus = input(0)->pull(destinationBus, numberOfFrames);
     68 
     69     if (!renderedBus)
     70         destinationBus->zero();
     71     else if (renderedBus != destinationBus) {
     72         // in-place processing was not possible - so copy
     73         destinationBus->copyFrom(*renderedBus);
     74     }
     75 
     76     // Let the context take care of any business at the end of each render quantum.
     77     context()->handlePostRenderTasks();
     78 
     79     // Advance current time.
     80     m_currentTime += numberOfFrames / sampleRate();
     81 }
     82 
     83 } // namespace WebCore
     84 
     85 #endif // ENABLE(WEB_AUDIO)
     86