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118 lines
4.7 KiB
C++
118 lines
4.7 KiB
C++
/*
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* Copyright (C) 2010 Google Inc. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of Apple Computer, Inc. ("Apple") nor the names of
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* its contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
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* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "FFTConvolver.h"
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#include "mozilla/PodOperations.h"
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using namespace mozilla;
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namespace WebCore {
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FFTConvolver::FFTConvolver(size_t fftSize)
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: m_frame(fftSize)
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, m_readWriteIndex(0)
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{
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m_inputBuffer.SetLength(fftSize);
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PodZero(m_inputBuffer.Elements(), fftSize);
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m_outputBuffer.SetLength(fftSize);
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PodZero(m_outputBuffer.Elements(), fftSize);
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m_lastOverlapBuffer.SetLength(fftSize / 2);
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PodZero(m_lastOverlapBuffer.Elements(), fftSize / 2);
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}
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void FFTConvolver::process(FFTBlock* fftKernel, const float* sourceP, float* destP, size_t framesToProcess)
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{
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size_t halfSize = fftSize() / 2;
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// framesToProcess must be an exact multiple of halfSize,
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// or halfSize is a multiple of framesToProcess when halfSize > framesToProcess.
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bool isGood = !(halfSize % framesToProcess && framesToProcess % halfSize);
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MOZ_ASSERT(isGood);
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if (!isGood)
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return;
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size_t numberOfDivisions = halfSize <= framesToProcess ? (framesToProcess / halfSize) : 1;
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size_t divisionSize = numberOfDivisions == 1 ? framesToProcess : halfSize;
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for (size_t i = 0; i < numberOfDivisions; ++i, sourceP += divisionSize, destP += divisionSize) {
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// Copy samples to input buffer (note contraint above!)
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float* inputP = m_inputBuffer.Elements();
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// Sanity check
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bool isCopyGood1 = sourceP && inputP && m_readWriteIndex + divisionSize <= m_inputBuffer.Length();
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MOZ_ASSERT(isCopyGood1);
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if (!isCopyGood1)
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return;
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memcpy(inputP + m_readWriteIndex, sourceP, sizeof(float) * divisionSize);
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// Copy samples from output buffer
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float* outputP = m_outputBuffer.Elements();
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// Sanity check
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bool isCopyGood2 = destP && outputP && m_readWriteIndex + divisionSize <= m_outputBuffer.Length();
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MOZ_ASSERT(isCopyGood2);
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if (!isCopyGood2)
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return;
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memcpy(destP, outputP + m_readWriteIndex, sizeof(float) * divisionSize);
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m_readWriteIndex += divisionSize;
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// Check if it's time to perform the next FFT
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if (m_readWriteIndex == halfSize) {
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// The input buffer is now filled (get frequency-domain version)
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m_frame.PerformFFT(m_inputBuffer.Elements());
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m_frame.Multiply(*fftKernel);
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m_frame.PerformInverseFFT(m_outputBuffer.Elements());
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// Overlap-add 1st half from previous time
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AudioBufferAddWithScale(m_lastOverlapBuffer.Elements(), 1.0f,
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m_outputBuffer.Elements(), halfSize);
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// Finally, save 2nd half of result
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bool isCopyGood3 = m_outputBuffer.Length() == 2 * halfSize && m_lastOverlapBuffer.Length() == halfSize;
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MOZ_ASSERT(isCopyGood3);
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if (!isCopyGood3)
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return;
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memcpy(m_lastOverlapBuffer.Elements(), m_outputBuffer.Elements() + halfSize, sizeof(float) * halfSize);
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// Reset index back to start for next time
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m_readWriteIndex = 0;
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}
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}
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}
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void FFTConvolver::reset()
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{
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PodZero(m_lastOverlapBuffer.Elements(), m_lastOverlapBuffer.Length());
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m_readWriteIndex = 0;
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}
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} // namespace WebCore
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