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      1 /*
      2  * Copyright (C) 2011, 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 WaveShaperDSPKernel_h
     26 #define WaveShaperDSPKernel_h
     27 
     28 #include "platform/audio/AudioArray.h"
     29 #include "platform/audio/AudioDSPKernel.h"
     30 #include "platform/audio/DownSampler.h"
     31 #include "platform/audio/UpSampler.h"
     32 #include "modules/webaudio/WaveShaperProcessor.h"
     33 #include "wtf/OwnPtr.h"
     34 
     35 namespace blink {
     36 
     37 class WaveShaperProcessor;
     38 
     39 // WaveShaperDSPKernel is an AudioDSPKernel and is responsible for non-linear distortion on one channel.
     40 
     41 class WaveShaperDSPKernel FINAL : public AudioDSPKernel {
     42 public:
     43     explicit WaveShaperDSPKernel(WaveShaperProcessor*);
     44 
     45     // AudioDSPKernel
     46     virtual void process(const float* source, float* dest, size_t framesToProcess) OVERRIDE;
     47     virtual void reset() OVERRIDE;
     48     virtual double tailTime() const OVERRIDE { return 0; }
     49     virtual double latencyTime() const OVERRIDE;
     50 
     51     // Oversampling requires more resources, so let's only allocate them if needed.
     52     void lazyInitializeOversampling();
     53 
     54 protected:
     55     // Apply the shaping curve.
     56     void processCurve(const float* source, float* dest, size_t framesToProcess);
     57 
     58     // Use up-sampling, process at the higher sample-rate, then down-sample.
     59     void processCurve2x(const float* source, float* dest, size_t framesToProcess);
     60     void processCurve4x(const float* source, float* dest, size_t framesToProcess);
     61 
     62     WaveShaperProcessor* waveShaperProcessor() { return static_cast<WaveShaperProcessor*>(processor()); }
     63 
     64     // Oversampling.
     65     OwnPtr<AudioFloatArray> m_tempBuffer;
     66     OwnPtr<AudioFloatArray> m_tempBuffer2;
     67     OwnPtr<UpSampler> m_upSampler;
     68     OwnPtr<DownSampler> m_downSampler;
     69     OwnPtr<UpSampler> m_upSampler2;
     70     OwnPtr<DownSampler> m_downSampler2;
     71 };
     72 
     73 } // namespace blink
     74 
     75 #endif // WaveShaperDSPKernel_h
     76