blob: 1017400a2824d1bba2c462c0673348bc14a5baa0 [file] [log] [blame]
/*
* Copyright (c) 2018 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/agc2/rnn_vad/fft_util.h"
#include <cmath>
#include "rtc_base/checks.h"
namespace webrtc {
namespace rnn_vad {
namespace {
constexpr size_t kHalfFrameSize = kFrameSize20ms24kHz / 2;
// Computes the first half of the Vorbis window.
std::array<float, kHalfFrameSize> ComputeHalfVorbisWindow() {
std::array<float, kHalfFrameSize> half_window{};
for (size_t i = 0; i < kHalfFrameSize; ++i) {
half_window[i] =
std::sin(0.5 * kPi * std::sin(0.5 * kPi * (i + 0.5) / kHalfFrameSize) *
std::sin(0.5 * kPi * (i + 0.5) / kHalfFrameSize));
}
return half_window;
}
} // namespace
BandAnalysisFft::BandAnalysisFft()
: half_window_(ComputeHalfVorbisWindow()),
fft_(static_cast<int>(input_buf_.size())) {}
BandAnalysisFft::~BandAnalysisFft() = default;
void BandAnalysisFft::ForwardFft(rtc::ArrayView<const float> samples,
rtc::ArrayView<std::complex<float>> dst) {
RTC_DCHECK_EQ(input_buf_.size(), samples.size());
RTC_DCHECK_EQ(samples.size(), dst.size());
// Apply windowing.
RTC_DCHECK_EQ(input_buf_.size(), 2 * half_window_.size());
for (size_t i = 0; i < input_buf_.size() / 2; ++i) {
input_buf_[i].real(samples[i] * half_window_[i]);
size_t j = kFrameSize20ms24kHz - i - 1;
input_buf_[j].real(samples[j] * half_window_[i]);
}
fft_.ForwardFft(kFrameSize20ms24kHz, input_buf_.data(), kFrameSize20ms24kHz,
dst.data());
}
} // namespace rnn_vad
} // namespace webrtc