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138 lines
4.4 KiB
C++
138 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 WEBRTC_MODULES_AUDIO_CODING_NETEQ_BACKGROUND_NOISE_H_
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#define WEBRTC_MODULES_AUDIO_CODING_NETEQ_BACKGROUND_NOISE_H_
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#include <string.h> // size_t
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#include "webrtc/base/constructormagic.h"
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#include "webrtc/modules/audio_coding/neteq/audio_multi_vector.h"
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#include "webrtc/modules/audio_coding/neteq/interface/neteq.h"
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#include "webrtc/system_wrappers/interface/scoped_ptr.h"
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#include "webrtc/typedefs.h"
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namespace webrtc {
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// Forward declarations.
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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 const int 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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void Update(const AudioMultiVector& sync_buffer,
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const PostDecodeVad& vad);
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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 |length| elements from |input| to the filter state. Will not copy
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// more than |kMaxLpcOrder| elements.
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void SetFilterState(size_t channel, const int16_t* input, size_t length);
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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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NetEq::BackgroundNoiseMode mode() const { return mode_; }
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// Sets the mode of the background noise playout for cases when there is long
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// duration of packet loss.
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void set_mode(NetEq::BackgroundNoiseMode mode) { mode_ = mode; }
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private:
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static const int kThresholdIncrement = 229; // 0.0035 in Q16.
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static const int kVecLen = 256;
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static const int kLogVecLen = 8; // log2(kVecLen).
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static const int kResidualLength = 64;
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static const int kLogResidualLength = 6; // log2(kResidualLength)
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struct ChannelParameters {
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// Constructor.
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ChannelParameters() {
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Reset();
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}
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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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int 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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scoped_ptr<ChannelParameters[]> channel_parameters_;
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bool initialized_;
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NetEq::BackgroundNoiseMode mode_;
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DISALLOW_COPY_AND_ASSIGN(BackgroundNoise);
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};
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} // namespace webrtc
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#endif // WEBRTC_MODULES_AUDIO_CODING_NETEQ_BACKGROUND_NOISE_H_
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