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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 AudioDestinationNode_h
     26 #define AudioDestinationNode_h
     27 
     28 #include "platform/audio/AudioBus.h"
     29 #include "platform/audio/AudioIOCallback.h"
     30 #include "platform/audio/AudioSourceProvider.h"
     31 #include "modules/webaudio/AudioBuffer.h"
     32 #include "modules/webaudio/AudioNode.h"
     33 
     34 namespace blink {
     35 
     36 class AudioBus;
     37 class AudioContext;
     38 
     39 class AudioDestinationNode : public AudioNode, public AudioIOCallback {
     40     DEFINE_WRAPPERTYPEINFO();
     41 public:
     42     AudioDestinationNode(AudioContext*, float sampleRate);
     43     virtual ~AudioDestinationNode();
     44 
     45     // AudioNode
     46     virtual void dispose() OVERRIDE;
     47     virtual void process(size_t) OVERRIDE FINAL { } // we're pulled by hardware so this is never called
     48 
     49     // The audio hardware calls render() to get the next render quantum of audio into destinationBus.
     50     // It will optionally give us local/live audio input in sourceBus (if it's not 0).
     51     virtual void render(AudioBus* sourceBus, AudioBus* destinationBus, size_t numberOfFrames) OVERRIDE FINAL;
     52 
     53     size_t currentSampleFrame() const { return m_currentSampleFrame; }
     54     double currentTime() const { return currentSampleFrame() / static_cast<double>(sampleRate()); }
     55 
     56     virtual unsigned long maxChannelCount() const { return 0; }
     57 
     58     virtual void startRendering() = 0;
     59 
     60 protected:
     61     // LocalAudioInputProvider allows us to expose an AudioSourceProvider for local/live audio input.
     62     // If there is local/live audio input, we call set() with the audio input data every render quantum.
     63     class LocalAudioInputProvider FINAL : public AudioSourceProvider {
     64     public:
     65         LocalAudioInputProvider()
     66             : m_sourceBus(AudioBus::create(2, AudioNode::ProcessingSizeInFrames)) // FIXME: handle non-stereo local input.
     67         {
     68         }
     69 
     70         void set(AudioBus* bus)
     71         {
     72             if (bus)
     73                 m_sourceBus->copyFrom(*bus);
     74         }
     75 
     76         // AudioSourceProvider.
     77         virtual void provideInput(AudioBus* destinationBus, size_t numberOfFrames) OVERRIDE
     78         {
     79             bool isGood = destinationBus && destinationBus->length() == numberOfFrames && m_sourceBus->length() == numberOfFrames;
     80             ASSERT(isGood);
     81             if (isGood)
     82                 destinationBus->copyFrom(*m_sourceBus);
     83         }
     84 
     85     private:
     86         RefPtr<AudioBus> m_sourceBus;
     87     };
     88 
     89     virtual double tailTime() const OVERRIDE FINAL { return 0; }
     90     virtual double latencyTime() const OVERRIDE FINAL { return 0; }
     91 
     92     // Counts the number of sample-frames processed by the destination.
     93     size_t m_currentSampleFrame;
     94 
     95     LocalAudioInputProvider m_localAudioInputProvider;
     96 };
     97 
     98 } // namespace blink
     99 
    100 #endif // AudioDestinationNode_h
    101