139 lines
4.4 KiB
C++
139 lines
4.4 KiB
C++
/*
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* Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#ifndef MODULES_AUDIO_CODING_NETEQ_BACKGROUND_NOISE_H_
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#define MODULES_AUDIO_CODING_NETEQ_BACKGROUND_NOISE_H_
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#include <string.h> // size_t
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#include <memory>
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#include "api/array_view.h"
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#include "rtc_base/constructor_magic.h"
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namespace webrtc {
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// Forward declarations.
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class AudioMultiVector;
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class PostDecodeVad;
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// This class handles estimation of background noise parameters.
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class BackgroundNoise {
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public:
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// TODO(hlundin): For 48 kHz support, increase kMaxLpcOrder to 10.
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// Will work anyway, but probably sound a little worse.
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static constexpr size_t kMaxLpcOrder = 8; // 32000 / 8000 + 4.
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explicit BackgroundNoise(size_t num_channels);
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virtual ~BackgroundNoise();
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void Reset();
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// Updates the parameter estimates based on the signal currently in the
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// |sync_buffer|, and on the latest decision in |vad| if it is running.
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// Returns true if the filter parameters are updated.
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bool Update(const AudioMultiVector& sync_buffer, const PostDecodeVad& vad);
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// Generates background noise given a random vector and writes the output to
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// |buffer|.
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void GenerateBackgroundNoise(rtc::ArrayView<const int16_t> random_vector,
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size_t channel,
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int mute_slope,
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bool too_many_expands,
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size_t num_noise_samples,
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int16_t* buffer);
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// Returns |energy_| for |channel|.
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int32_t Energy(size_t channel) const;
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// Sets the value of |mute_factor_| for |channel| to |value|.
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void SetMuteFactor(size_t channel, int16_t value);
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// Returns |mute_factor_| for |channel|.
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int16_t MuteFactor(size_t channel) const;
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// Returns a pointer to |filter_| for |channel|.
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const int16_t* Filter(size_t channel) const;
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// Returns a pointer to |filter_state_| for |channel|.
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const int16_t* FilterState(size_t channel) const;
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// Copies |input| to the filter state. Will not copy more than |kMaxLpcOrder|
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// elements.
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void SetFilterState(size_t channel, rtc::ArrayView<const int16_t> input);
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// Returns |scale_| for |channel|.
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int16_t Scale(size_t channel) const;
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// Returns |scale_shift_| for |channel|.
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int16_t ScaleShift(size_t channel) const;
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// Accessors.
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bool initialized() const { return initialized_; }
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private:
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static const int kThresholdIncrement = 229; // 0.0035 in Q16.
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static const size_t kVecLen = 256;
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static const int kLogVecLen = 8; // log2(kVecLen).
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static const size_t kResidualLength = 64;
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static const int16_t kLogResidualLength = 6; // log2(kResidualLength)
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struct ChannelParameters {
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// Constructor.
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ChannelParameters() { Reset(); }
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void Reset() {
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energy = 2500;
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max_energy = 0;
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energy_update_threshold = 500000;
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low_energy_update_threshold = 0;
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memset(filter_state, 0, sizeof(filter_state));
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memset(filter, 0, sizeof(filter));
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filter[0] = 4096;
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mute_factor = 0;
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scale = 20000;
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scale_shift = 24;
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}
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int32_t energy;
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int32_t max_energy;
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int32_t energy_update_threshold;
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int32_t low_energy_update_threshold;
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int16_t filter_state[kMaxLpcOrder];
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int16_t filter[kMaxLpcOrder + 1];
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int16_t mute_factor;
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int16_t scale;
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int16_t scale_shift;
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};
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int32_t CalculateAutoCorrelation(const int16_t* signal,
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size_t length,
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int32_t* auto_correlation) const;
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// Increments the energy threshold by a factor 1 + |kThresholdIncrement|.
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void IncrementEnergyThreshold(size_t channel, int32_t sample_energy);
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// Updates the filter parameters.
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void SaveParameters(size_t channel,
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const int16_t* lpc_coefficients,
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const int16_t* filter_state,
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int32_t sample_energy,
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int32_t residual_energy);
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size_t num_channels_;
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std::unique_ptr<ChannelParameters[]> channel_parameters_;
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bool initialized_;
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RTC_DISALLOW_COPY_AND_ASSIGN(BackgroundNoise);
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};
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} // namespace webrtc
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#endif // MODULES_AUDIO_CODING_NETEQ_BACKGROUND_NOISE_H_
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