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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 Computer, 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 "FFTConvolver.h"
#include "mozilla/PodOperations.h"
using namespace mozilla;
namespace WebCore {
FFTConvolver::FFTConvolver(size_t fftSize, size_t renderPhase)
: m_frame(fftSize)
, m_readWriteIndex(renderPhase % (fftSize / 2))
{
MOZ_ASSERT(fftSize >= 2 * WEBAUDIO_BLOCK_SIZE);
m_inputBuffer.SetLength(fftSize);
PodZero(m_inputBuffer.Elements(), fftSize);
m_outputBuffer.SetLength(fftSize);
PodZero(m_outputBuffer.Elements(), fftSize);
m_lastOverlapBuffer.SetLength(fftSize / 2);
PodZero(m_lastOverlapBuffer.Elements(), fftSize / 2);
}
size_t FFTConvolver::sizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
{
size_t amount = 0;
amount += m_frame.SizeOfExcludingThis(aMallocSizeOf);
amount += m_inputBuffer.ShallowSizeOfExcludingThis(aMallocSizeOf);
amount += m_outputBuffer.ShallowSizeOfExcludingThis(aMallocSizeOf);
amount += m_lastOverlapBuffer.ShallowSizeOfExcludingThis(aMallocSizeOf);
return amount;
}
size_t FFTConvolver::sizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
{
return aMallocSizeOf(this) + sizeOfExcludingThis(aMallocSizeOf);
}
const float* FFTConvolver::process(FFTBlock* fftKernel, const float* sourceP)
{
size_t halfSize = fftSize() / 2;
// WEBAUDIO_BLOCK_SIZE must be an exact multiple of halfSize,
// halfSize must be a multiple of WEBAUDIO_BLOCK_SIZE
// and > WEBAUDIO_BLOCK_SIZE.
MOZ_ASSERT(halfSize % WEBAUDIO_BLOCK_SIZE == 0 &&
WEBAUDIO_BLOCK_SIZE <= halfSize);
// Copy samples to input buffer (note contraint above!)
float* inputP = m_inputBuffer.Elements();
MOZ_ASSERT(sourceP && inputP && m_readWriteIndex + WEBAUDIO_BLOCK_SIZE <= m_inputBuffer.Length());
memcpy(inputP + m_readWriteIndex, sourceP, sizeof(float) * WEBAUDIO_BLOCK_SIZE);
float* outputP = m_outputBuffer.Elements();
m_readWriteIndex += WEBAUDIO_BLOCK_SIZE;
// 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.PerformFFT(m_inputBuffer.Elements());
m_frame.Multiply(*fftKernel);
m_frame.GetInverseWithoutScaling(m_outputBuffer.Elements());
// Overlap-add 1st half from previous time
AudioBufferAddWithScale(m_lastOverlapBuffer.Elements(), 1.0f,
m_outputBuffer.Elements(), halfSize);
// Finally, save 2nd half of result
MOZ_ASSERT(m_outputBuffer.Length() == 2 * halfSize && m_lastOverlapBuffer.Length() == halfSize);
memcpy(m_lastOverlapBuffer.Elements(), m_outputBuffer.Elements() + halfSize, sizeof(float) * halfSize);
// Reset index back to start for next time
m_readWriteIndex = 0;
}
return outputP + m_readWriteIndex;
}
void FFTConvolver::reset()
{
PodZero(m_lastOverlapBuffer.Elements(), m_lastOverlapBuffer.Length());
m_readWriteIndex = 0;
}
size_t FFTConvolver::latencyFrames() const
{
return std::max<size_t>(fftSize()/2, WEBAUDIO_BLOCK_SIZE) -
WEBAUDIO_BLOCK_SIZE;
}
} // namespace WebCore
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