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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 #include "config.h"
     30 
     31 #if ENABLE(WEB_AUDIO)
     32 
     33 #include "core/platform/audio/FFTConvolver.h"
     34 
     35 #include "core/platform/audio/VectorMath.h"
     36 
     37 namespace WebCore {
     38 
     39 using namespace VectorMath;
     40 
     41 FFTConvolver::FFTConvolver(size_t fftSize)
     42     : m_frame(fftSize)
     43     , m_readWriteIndex(0)
     44     , m_inputBuffer(fftSize) // 2nd half of buffer is always zeroed
     45     , m_outputBuffer(fftSize)
     46     , m_lastOverlapBuffer(fftSize / 2)
     47 {
     48 }
     49 
     50 void FFTConvolver::process(FFTFrame* fftKernel, const float* sourceP, float* destP, size_t framesToProcess)
     51 {
     52     size_t halfSize = fftSize() / 2;
     53 
     54     // framesToProcess must be an exact multiple of halfSize,
     55     // or halfSize is a multiple of framesToProcess when halfSize > framesToProcess.
     56     bool isGood = !(halfSize % framesToProcess && framesToProcess % halfSize);
     57     ASSERT(isGood);
     58     if (!isGood)
     59         return;
     60 
     61     size_t numberOfDivisions = halfSize <= framesToProcess ? (framesToProcess / halfSize) : 1;
     62     size_t divisionSize = numberOfDivisions == 1 ? framesToProcess : halfSize;
     63 
     64     for (size_t i = 0; i < numberOfDivisions; ++i, sourceP += divisionSize, destP += divisionSize) {
     65         // Copy samples to input buffer (note contraint above!)
     66         float* inputP = m_inputBuffer.data();
     67 
     68         // Sanity check
     69         bool isCopyGood1 = sourceP && inputP && m_readWriteIndex + divisionSize <= m_inputBuffer.size();
     70         ASSERT(isCopyGood1);
     71         if (!isCopyGood1)
     72             return;
     73 
     74         memcpy(inputP + m_readWriteIndex, sourceP, sizeof(float) * divisionSize);
     75 
     76         // Copy samples from output buffer
     77         float* outputP = m_outputBuffer.data();
     78 
     79         // Sanity check
     80         bool isCopyGood2 = destP && outputP && m_readWriteIndex + divisionSize <= m_outputBuffer.size();
     81         ASSERT(isCopyGood2);
     82         if (!isCopyGood2)
     83             return;
     84 
     85         memcpy(destP, outputP + m_readWriteIndex, sizeof(float) * divisionSize);
     86         m_readWriteIndex += divisionSize;
     87 
     88         // Check if it's time to perform the next FFT
     89         if (m_readWriteIndex == halfSize) {
     90             // The input buffer is now filled (get frequency-domain version)
     91             m_frame.doFFT(m_inputBuffer.data());
     92             m_frame.multiply(*fftKernel);
     93             m_frame.doInverseFFT(m_outputBuffer.data());
     94 
     95             // Overlap-add 1st half from previous time
     96             vadd(m_outputBuffer.data(), 1, m_lastOverlapBuffer.data(), 1, m_outputBuffer.data(), 1, halfSize);
     97 
     98             // Finally, save 2nd half of result
     99             bool isCopyGood3 = m_outputBuffer.size() == 2 * halfSize && m_lastOverlapBuffer.size() == halfSize;
    100             ASSERT(isCopyGood3);
    101             if (!isCopyGood3)
    102                 return;
    103 
    104             memcpy(m_lastOverlapBuffer.data(), m_outputBuffer.data() + halfSize, sizeof(float) * halfSize);
    105 
    106             // Reset index back to start for next time
    107             m_readWriteIndex = 0;
    108         }
    109     }
    110 }
    111 
    112 void FFTConvolver::reset()
    113 {
    114     m_lastOverlapBuffer.zero();
    115     m_readWriteIndex = 0;
    116 }
    117 
    118 } // namespace WebCore
    119 
    120 #endif // ENABLE(WEB_AUDIO)
    121