third_party/WebKit/Source/platform/audio/FFTConvolver.cpp

   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 "platform/audio/FFTConvolver.h"
  34
  35 #include "platform/audio/VectorMath.h"
  36
  37 namespace blink {
  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 blink
 119
 120 #endif // ENABLE(WEB_AUDIO)