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