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diff --git a/webrtc/modules/audio_processing/agc2/rnn_vad/spectral_features.h b/webrtc/modules/audio_processing/agc2/rnn_vad/spectral_features.h
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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 <cstddef>
+#include <memory>
+#include <vector>
+
+#include "api/array_view.h"
+#include "modules/audio_processing/agc2/rnn_vad/common.h"
+#include "modules/audio_processing/agc2/rnn_vad/ring_buffer.h"
+#include "modules/audio_processing/agc2/rnn_vad/spectral_features_internal.h"
+#include "modules/audio_processing/agc2/rnn_vad/symmetric_matrix_buffer.h"
+#include "modules/audio_processing/utility/pffft_wrapper.h"
+
+namespace webrtc {
+namespace rnn_vad {
+
+// 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,
+      rtc::ArrayView<float, kNumBands - kNumLowerBands> higher_bands_cepstrum,
+      rtc::ArrayView<float, kNumLowerBands> average,
+      rtc::ArrayView<float, kNumLowerBands> first_derivative,
+      rtc::ArrayView<float, kNumLowerBands> second_derivative,
+      rtc::ArrayView<float, kNumLowerBands> bands_cross_corr,
+      float* variability);
+
+ private:
+  void ComputeAvgAndDerivatives(
+      rtc::ArrayView<float, kNumLowerBands> average,
+      rtc::ArrayView<float, kNumLowerBands> first_derivative,
+      rtc::ArrayView<float, kNumLowerBands> second_derivative) const;
+  void ComputeNormalizedCepstralCorrelation(
+      rtc::ArrayView<float, kNumLowerBands> bands_cross_corr);
+  float ComputeVariability() const;
+
+  const std::array<float, kFrameSize20ms24kHz / 2> half_window_;
+  Pffft fft_;
+  std::unique_ptr<Pffft::FloatBuffer> fft_buffer_;
+  std::unique_ptr<Pffft::FloatBuffer> reference_frame_fft_;
+  std::unique_ptr<Pffft::FloatBuffer> lagged_frame_fft_;
+  SpectralCorrelator spectral_correlator_;
+  std::array<float, kOpusBands24kHz> reference_frame_bands_energy_;
+  std::array<float, kOpusBands24kHz> lagged_frame_bands_energy_;
+  std::array<float, kOpusBands24kHz> bands_cross_corr_;
+  const std::array<float, kNumBands * kNumBands> dct_table_;
+  RingBuffer<float, kNumBands, kCepstralCoeffsHistorySize>
+      cepstral_coeffs_ring_buf_;
+  SymmetricMatrixBuffer<float, kCepstralCoeffsHistorySize> cepstral_diffs_buf_;
+};
+
+}  // namespace rnn_vad
+}  // namespace webrtc
+
+#endif  // MODULES_AUDIO_PROCESSING_AGC2_RNN_VAD_SPECTRAL_FEATURES_H_