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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  *
      8  * 1.  Redistributions of source code must retain the above copyright
      9  *     notice, this list of conditions and the following disclaimer.
     10  * 2.  Redistributions in binary form must reproduce the above copyright
     11  *     notice, this list of conditions and the following disclaimer in the
     12  *     documentation and/or other materials provided with the distribution.
     13  * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
     14  *     its contributors may be used to endorse or promote products derived
     15  *     from this software without specific prior written permission.
     16  *
     17  * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
     18  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
     19  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
     20  * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
     21  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
     22  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
     23  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
     24  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     27  */
     28 
     29 #ifndef ReverbConvolverStage_h
     30 #define ReverbConvolverStage_h
     31 
     32 #include "AudioArray.h"
     33 #include "FFTFrame.h"
     34 #include <wtf/OwnPtr.h>
     35 
     36 namespace WebCore {
     37 
     38 class ReverbAccumulationBuffer;
     39 class ReverbConvolver;
     40 class FFTConvolver;
     41 
     42 // A ReverbConvolverStage represents the convolution associated with a sub-section of a large impulse response.
     43 // It incorporates a delay line to account for the offset of the sub-section within the larger impulse response.
     44 class ReverbConvolverStage {
     45 public:
     46     // renderPhase is useful to know so that we can manipulate the pre versus post delay so that stages will perform
     47     // their heavy work (FFT processing) on different slices to balance the load in a real-time thread.
     48     ReverbConvolverStage(float* impulseResponse, size_t responseLength, size_t reverbTotalLatency, size_t stageOffset, size_t stageLength,
     49                          size_t fftSize, size_t renderPhase, size_t renderSliceSize, ReverbAccumulationBuffer* accumulationBuffer);
     50 
     51     // WARNING: framesToProcess must be such that it evenly divides the delay buffer size (stage_offset).
     52     void process(float* source, size_t framesToProcess);
     53 
     54     void processInBackground(ReverbConvolver* convolver, size_t framesToProcess);
     55 
     56     void reset();
     57 
     58     // Useful for background processing
     59     int inputReadIndex() const { return m_inputReadIndex; }
     60 
     61 private:
     62     FFTFrame m_fftKernel;
     63     OwnPtr<FFTConvolver> m_convolver;
     64 
     65     AudioFloatArray m_preDelayBuffer;
     66 
     67     ReverbAccumulationBuffer* m_accumulationBuffer;
     68     int m_accumulationReadIndex;
     69     int m_inputReadIndex;
     70 
     71     size_t m_preDelayLength;
     72     size_t m_postDelayLength;
     73     size_t m_preReadWriteIndex;
     74     size_t m_framesProcessed;
     75 
     76     AudioFloatArray m_temporaryBuffer;
     77 
     78     size_t m_impulseResponseLength;
     79 };
     80 
     81 } // namespace WebCore
     82 
     83 #endif // ReverbConvolverStage_h
     84