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/*
* 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.
*/
#ifndef MODULES_AUDIO_PROCESSING_AGC2_RNN_VAD_SPECTRAL_FEATURES_H_
#define MODULES_AUDIO_PROCESSING_AGC2_RNN_VAD_SPECTRAL_FEATURES_H_
#include <array>
#include <complex>
#include <cstddef>
#include <vector>
#include "api/array_view.h"
#include "modules/audio_processing/agc2/rnn_vad/common.h"
#include "modules/audio_processing/agc2/rnn_vad/fft_util.h"
#include "modules/audio_processing/agc2/rnn_vad/ring_buffer.h"
#include "modules/audio_processing/agc2/rnn_vad/symmetric_matrix_buffer.h"
namespace webrtc {
namespace rnn_vad {
// View on spectral features.
class SpectralFeaturesView {
public:
SpectralFeaturesView(rtc::ArrayView<float, kNumBands - kNumLowerBands> coeffs,
rtc::ArrayView<float, kNumLowerBands> average,
rtc::ArrayView<float, kNumLowerBands> first_derivative,
rtc::ArrayView<float, kNumLowerBands> second_derivative,
rtc::ArrayView<float, kNumLowerBands> cross_correlations,
float* variability);
SpectralFeaturesView(const SpectralFeaturesView&);
~SpectralFeaturesView();
// Higher bands spectral coefficients.
const rtc::ArrayView<float, kNumBands - kNumLowerBands> coeffs;
// Average and first and second derivative over time for the lower bands.
const rtc::ArrayView<float, kNumLowerBands> average;
const rtc::ArrayView<float, kNumLowerBands> first_derivative;
const rtc::ArrayView<float, kNumLowerBands> second_derivative;
// Spectral cross-correlation for the lower bands.
const rtc::ArrayView<float, kNumLowerBands> cross_correlations;
// Spectral variability score.
float* const variability;
};
// Class to compute spectral features.
class SpectralFeaturesExtractor {
public:
SpectralFeaturesExtractor();
SpectralFeaturesExtractor(const SpectralFeaturesExtractor&) = delete;
SpectralFeaturesExtractor& operator=(const SpectralFeaturesExtractor&) =
delete;
~SpectralFeaturesExtractor();
// Resets the internal state of the feature extractor.
void Reset();
// Analyzes a pair of reference and lagged frames from the pitch buffer,
// detects silence and computes features. If silence is detected, the output
// is neither computed nor written.
bool CheckSilenceComputeFeatures(
rtc::ArrayView<const float, kFrameSize20ms24kHz> reference_frame,
rtc::ArrayView<const float, kFrameSize20ms24kHz> lagged_frame,
SpectralFeaturesView spectral_features);
private:
void ComputeAvgAndDerivatives(
rtc::ArrayView<float, kNumLowerBands> average,
rtc::ArrayView<float, kNumLowerBands> first_derivative,
rtc::ArrayView<float, kNumLowerBands> second_derivative);
void ComputeCrossCorrelation(
rtc::ArrayView<float, kNumLowerBands> cross_correlations);
float ComputeVariability();
BandAnalysisFft fft_;
std::vector<std::complex<float>> reference_frame_fft_;
std::vector<std::complex<float>> lagged_frame_fft_;
std::array<float, kNumBands> reference_frame_energy_coeffs_{};
std::array<float, kNumBands> lagged_frame_energy_coeffs_{};
const std::array<size_t, kNumBands> band_boundaries_;
const std::array<float, kNumBands * kNumBands> dct_table_;
RingBuffer<float, kNumBands, kSpectralCoeffsHistorySize>
spectral_coeffs_ring_buf_;
SymmetricMatrixBuffer<float, kSpectralCoeffsHistorySize> spectral_diffs_buf_;
};
} // namespace rnn_vad
} // namespace webrtc
#endif // MODULES_AUDIO_PROCESSING_AGC2_RNN_VAD_SPECTRAL_FEATURES_H_