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