mirror of
https://github.com/danog/libtgvoip.git
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5caaaafa42
I'm now using the entire audio processing module from WebRTC as opposed to individual DSP algorithms pulled from there before. Seems to work better this way.
92 lines
2.9 KiB
C++
92 lines
2.9 KiB
C++
/*
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* Copyright (c) 2015 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#include "common_audio/real_fourier_ooura.h"
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#include <algorithm>
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#include <cmath>
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#include "common_audio/third_party/fft4g/fft4g.h"
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#include "rtc_base/checks.h"
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namespace webrtc {
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using std::complex;
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namespace {
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void Conjugate(complex<float>* array, size_t complex_length) {
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std::for_each(array, array + complex_length,
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[=](complex<float>& v) { v = std::conj(v); });
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}
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size_t ComputeWorkIpSize(size_t fft_length) {
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return static_cast<size_t>(
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2 + std::ceil(std::sqrt(static_cast<float>(fft_length))));
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}
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} // namespace
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RealFourierOoura::RealFourierOoura(int fft_order)
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: order_(fft_order),
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length_(FftLength(order_)),
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complex_length_(ComplexLength(order_)),
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// Zero-initializing work_ip_ will cause rdft to initialize these work
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// arrays on the first call.
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work_ip_(new size_t[ComputeWorkIpSize(length_)]()),
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work_w_(new float[complex_length_]()) {
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RTC_CHECK_GE(fft_order, 1);
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}
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RealFourierOoura::~RealFourierOoura() = default;
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void RealFourierOoura::Forward(const float* src, complex<float>* dest) const {
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{
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// This cast is well-defined since C++11. See "Non-static data members" at:
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// http://en.cppreference.com/w/cpp/numeric/complex
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auto* dest_float = reinterpret_cast<float*>(dest);
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std::copy(src, src + length_, dest_float);
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WebRtc_rdft(length_, 1, dest_float, work_ip_.get(), work_w_.get());
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}
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// Ooura places real[n/2] in imag[0].
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dest[complex_length_ - 1] = complex<float>(dest[0].imag(), 0.0f);
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dest[0] = complex<float>(dest[0].real(), 0.0f);
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// Ooura returns the conjugate of the usual Fourier definition.
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Conjugate(dest, complex_length_);
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}
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void RealFourierOoura::Inverse(const complex<float>* src, float* dest) const {
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{
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auto* dest_complex = reinterpret_cast<complex<float>*>(dest);
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// The real output array is shorter than the input complex array by one
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// complex element.
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const size_t dest_complex_length = complex_length_ - 1;
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std::copy(src, src + dest_complex_length, dest_complex);
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// Restore Ooura's conjugate definition.
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Conjugate(dest_complex, dest_complex_length);
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// Restore real[n/2] to imag[0].
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dest_complex[0] =
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complex<float>(dest_complex[0].real(), src[complex_length_ - 1].real());
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}
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WebRtc_rdft(length_, -1, dest, work_ip_.get(), work_w_.get());
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// Ooura returns a scaled version.
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const float scale = 2.0f / length_;
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std::for_each(dest, dest + length_, [scale](float& v) { v *= scale; });
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}
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int RealFourierOoura::order() const {
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return order_;
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}
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} // namespace webrtc
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