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/*
* Copyright (C) 2011 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.
*
* 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.
*/
// FFTFrame implementation using FFmpeg's RDFT algorithm,
// suitable for use on Windows and Linux.
#include "config.h"
#if ENABLE(WEB_AUDIO)
#if USE(WEBAUDIO_FFMPEG)
#include "platform/audio/FFTFrame.h"
#include "platform/audio/VectorMath.h"
extern "C" {
#include <libavcodec/avfft.h>
}
#include "wtf/MathExtras.h"
namespace blink {
#if ENABLE(ASSERT)
const int kMaxFFTPow2Size = 24;
#endif
// Normal constructor: allocates for a given fftSize.
FFTFrame::FFTFrame(unsigned fftSize)
: m_FFTSize(fftSize)
, m_log2FFTSize(static_cast<unsigned>(log2(fftSize)))
, m_realData(fftSize / 2)
, m_imagData(fftSize / 2)
, m_forwardContext(0)
, m_inverseContext(0)
, m_complexData(fftSize)
{
// We only allow power of two.
ASSERT(1UL << m_log2FFTSize == m_FFTSize);
m_forwardContext = contextForSize(fftSize, DFT_R2C);
m_inverseContext = contextForSize(fftSize, IDFT_C2R);
}
// Creates a blank/empty frame (interpolate() must later be called).
FFTFrame::FFTFrame()
: m_FFTSize(0)
, m_log2FFTSize(0)
, m_forwardContext(0)
, m_inverseContext(0)
{
}
// Copy constructor.
FFTFrame::FFTFrame(const FFTFrame& frame)
: m_FFTSize(frame.m_FFTSize)
, m_log2FFTSize(frame.m_log2FFTSize)
, m_realData(frame.m_FFTSize / 2)
, m_imagData(frame.m_FFTSize / 2)
, m_forwardContext(0)
, m_inverseContext(0)
, m_complexData(frame.m_FFTSize)
{
m_forwardContext = contextForSize(m_FFTSize, DFT_R2C);
m_inverseContext = contextForSize(m_FFTSize, IDFT_C2R);
// Copy/setup frame data.
unsigned nbytes = sizeof(float) * (m_FFTSize / 2);
memcpy(realData(), frame.realData(), nbytes);
memcpy(imagData(), frame.imagData(), nbytes);
}
void FFTFrame::initialize()
{
}
void FFTFrame::cleanup()
{
}
FFTFrame::~FFTFrame()
{
av_rdft_end(m_forwardContext);
av_rdft_end(m_inverseContext);
}
void FFTFrame::doFFT(const float* data)
{
// Copy since processing is in-place.
float* p = m_complexData.data();
memcpy(p, data, sizeof(float) * m_FFTSize);
// Compute Forward transform.
av_rdft_calc(m_forwardContext, p);
// De-interleave to separate real and complex arrays.
int len = m_FFTSize / 2;
float* real = m_realData.data();
float* imag = m_imagData.data();
for (int i = 0; i < len; ++i) {
int baseComplexIndex = 2 * i;
// m_realData[0] is the DC component and m_imagData[0] is the nyquist component
// since the interleaved complex data is packed.
real[i] = p[baseComplexIndex];
imag[i] = p[baseComplexIndex + 1];
}
}
void FFTFrame::doInverseFFT(float* data)
{
// Prepare interleaved data.
float* interleavedData = getUpToDateComplexData();
// Compute inverse transform.
av_rdft_calc(m_inverseContext, interleavedData);
// Scale so that a forward then inverse FFT yields exactly the original data. For some reason
// av_rdft_calc above returns values that are half of what I expect. Hence make the scale factor
// twice as large to compensate for that.
const float scale = 2.0 / m_FFTSize;
VectorMath::vsmul(interleavedData, 1, &scale, data, 1, m_FFTSize);
}
float* FFTFrame::getUpToDateComplexData()
{
// FIXME: if we can't completely get rid of this method, SSE
// optimization could be considered if it shows up hot on profiles.
int len = m_FFTSize / 2;
const float* real = m_realData.data();
const float* imag = m_imagData.data();
float* c = m_complexData.data();
for (int i = 0; i < len; ++i) {
int baseComplexIndex = 2 * i;
c[baseComplexIndex] = real[i];
c[baseComplexIndex + 1] = imag[i];
}
return const_cast<float*>(m_complexData.data());
}
RDFTContext* FFTFrame::contextForSize(unsigned fftSize, int trans)
{
// FIXME: This is non-optimal. Ideally, we'd like to share the contexts for FFTFrames of the same size.
// But FFmpeg's RDFT uses a scratch buffer inside the context and so they are not thread-safe.
// We could improve this by sharing the FFTFrames on a per-thread basis.
ASSERT(fftSize);
int pow2size = static_cast<int>(log2(fftSize));
ASSERT(pow2size < kMaxFFTPow2Size);
RDFTContext* context = av_rdft_init(pow2size, (RDFTransformType)trans);
return context;
}
} // namespace blink
#endif // USE(WEBAUDIO_FFMPEG)
#endif // ENABLE(WEB_AUDIO)
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