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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.
*/
#ifndef MODULES_AUDIO_PROCESSING_NS_WIENER_FILTER_H_
#define MODULES_AUDIO_PROCESSING_NS_WIENER_FILTER_H_
#include <array>
#include "api/array_view.h"
#include "modules/audio_processing/ns/ns_common.h"
#include "modules/audio_processing/ns/suppression_params.h"
namespace webrtc {
// Estimates a Wiener-filter based frequency domain noise reduction filter.
class WienerFilter {
public:
explicit WienerFilter(const SuppressionParams& suppression_params);
WienerFilter(const WienerFilter&) = delete;
WienerFilter& operator=(const WienerFilter&) = delete;
// Updates the filter estimate.
void Update(
int32_t num_analyzed_frames,
rtc::ArrayView<const float, kFftSizeBy2Plus1> noise_spectrum,
rtc::ArrayView<const float, kFftSizeBy2Plus1> prev_noise_spectrum,
rtc::ArrayView<const float, kFftSizeBy2Plus1> parametric_noise_spectrum,
rtc::ArrayView<const float, kFftSizeBy2Plus1> signal_spectrum);
// Compute an overall gain scaling factor.
float ComputeOverallScalingFactor(int32_t num_analyzed_frames,
float prior_speech_probability,
float energy_before_filtering,
float energy_after_filtering) const;
// Returns the filter.
rtc::ArrayView<const float, kFftSizeBy2Plus1> get_filter() const {
return filter_;
}
private:
const SuppressionParams& suppression_params_;
std::array<float, kFftSizeBy2Plus1> spectrum_prev_process_;
std::array<float, kFftSizeBy2Plus1> initial_spectral_estimate_;
std::array<float, kFftSizeBy2Plus1> filter_;
};
} // namespace webrtc
#endif // MODULES_AUDIO_PROCESSING_NS_WIENER_FILTER_H_
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