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a55f314420
Setting up the FFT tables turns out to be quite expensive because of the large number of calls to sin() and cos(). In the future we may want to look into having a global cache of FFT tables per size, in order to pay the cost of setting each one of them up only once. --HG-- extra : rebase_source : 871d11e7f74db9e3e6c704da9518d40cba3deb8a
111 lines
2.7 KiB
C++
111 lines
2.7 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim:set ts=2 sw=2 sts=2 et cindent: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef FFTBlock_h_
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#define FFTBlock_h_
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#include "nsTArray.h"
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#include "AudioNodeEngine.h"
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#include "kiss_fft/kiss_fftr.h"
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namespace mozilla {
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// This class defines an FFT block, loosely modeled after Blink's FFTFrame
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// class to make sharing code with Blink easy.
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// Currently it's implemented on top of KissFFT on all platforms.
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class FFTBlock {
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public:
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explicit FFTBlock(uint32_t aFFTSize)
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: mFFT(nullptr)
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, mIFFT(nullptr)
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, mFFTSize(aFFTSize)
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{
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mOutputBuffer.SetLength(aFFTSize / 2 + 1);
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PodZero(mOutputBuffer.Elements(), aFFTSize / 2 + 1);
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}
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~FFTBlock()
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{
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free(mFFT);
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free(mIFFT);
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}
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void PerformFFT(const float* aData)
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{
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EnsureFFT();
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kiss_fftr(mFFT, aData, mOutputBuffer.Elements());
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}
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void PerformInverseFFT(float* aData)
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{
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EnsureIFFT();
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kiss_fftri(mIFFT, mOutputBuffer.Elements(), aData);
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for (uint32_t i = 0; i < mFFTSize; ++i) {
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aData[i] /= mFFTSize;
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}
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}
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void Multiply(const FFTBlock& aFrame)
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{
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BufferComplexMultiply(reinterpret_cast<const float*>(mOutputBuffer.Elements()),
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reinterpret_cast<const float*>(aFrame.mOutputBuffer.Elements()),
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reinterpret_cast<float*>(mOutputBuffer.Elements()),
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mFFTSize / 2 + 1);
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}
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void PerformPaddedFFT(const float* aData, size_t dataSize)
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{
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MOZ_ASSERT(dataSize <= FFTSize());
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nsTArray<float> paddedData;
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paddedData.SetLength(FFTSize());
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PodCopy(paddedData.Elements(), aData, dataSize);
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PodZero(paddedData.Elements() + dataSize, mFFTSize - dataSize);
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PerformFFT(paddedData.Elements());
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}
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void SetFFTSize(uint32_t aSize)
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{
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mFFTSize = aSize;
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mOutputBuffer.SetLength(aSize / 2 + 1);
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PodZero(mOutputBuffer.Elements(), aSize / 2 + 1);
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mFFT = mIFFT = nullptr;
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}
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uint32_t FFTSize() const
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{
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return mFFTSize;
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}
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float RealData(uint32_t aIndex) const
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{
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return mOutputBuffer[aIndex].r;
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}
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float ImagData(uint32_t aIndex) const
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{
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return mOutputBuffer[aIndex].i;
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}
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private:
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void EnsureFFT()
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{
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if (!mFFT) {
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mFFT = kiss_fftr_alloc(mFFTSize, 0, nullptr, nullptr);
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}
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}
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void EnsureIFFT()
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{
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if (!mIFFT) {
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mIFFT = kiss_fftr_alloc(mFFTSize, 1, nullptr, nullptr);
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}
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}
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private:
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kiss_fftr_cfg mFFT, mIFFT;
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nsTArray<kiss_fft_cpx> mOutputBuffer;
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uint32_t mFFTSize;
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};
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}
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#endif
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