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/*
* Copyright (c) 2019 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#include "modules/audio_processing/ns/ns_fft.h"
#include "common_audio/third_party/ooura/fft_size_256/fft4g.h"
namespace webrtc {
NrFft::NrFft() : bit_reversal_state_(kFftSize / 2), tables_(kFftSize / 2) {
// Initialize WebRtc_rdt (setting (bit_reversal_state_[0] to 0 triggers
// initialization)
bit_reversal_state_[0] = 0.f;
std::array<float, kFftSize> tmp_buffer;
tmp_buffer.fill(0.f);
WebRtc_rdft(kFftSize, 1, tmp_buffer.data(), bit_reversal_state_.data(),
tables_.data());
}
void NrFft::Fft(ArrayView<float, kFftSize> time_data,
ArrayView<float, kFftSize> real,
ArrayView<float, kFftSize> imag) {
WebRtc_rdft(kFftSize, 1, time_data.data(), bit_reversal_state_.data(),
tables_.data());
imag[0] = 0;
real[0] = time_data[0];
imag[kFftSizeBy2Plus1 - 1] = 0;
real[kFftSizeBy2Plus1 - 1] = time_data[1];
for (size_t i = 1; i < kFftSizeBy2Plus1 - 1; ++i) {
real[i] = time_data[2 * i];
imag[i] = time_data[2 * i + 1];
}
}
void NrFft::Ifft(ArrayView<const float> real,
ArrayView<const float> imag,
ArrayView<float> time_data) {
time_data[0] = real[0];
time_data[1] = real[kFftSizeBy2Plus1 - 1];
for (size_t i = 1; i < kFftSizeBy2Plus1 - 1; ++i) {
time_data[2 * i] = real[i];
time_data[2 * i + 1] = imag[i];
}
WebRtc_rdft(kFftSize, -1, time_data.data(), bit_reversal_state_.data(),
tables_.data());
// Scale the output
constexpr float kScaling = 2.f / kFftSize;
for (float& d : time_data) {
d *= kScaling;
}
}
} // namespace webrtc
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