1 /* 2 * Copyright (c) 2012 The WebRTC project authors. All Rights Reserved. 3 * 4 * Use of this source code is governed by a BSD-style license 5 * that can be found in the LICENSE file in the root of the source 6 * tree. An additional intellectual property rights grant can be found 7 * in the file PATENTS. All contributing project authors may 8 * be found in the AUTHORS file in the root of the source tree. 9 */ 10 11 #ifndef WEBRTC_MODULES_AUDIO_CODING_NETEQ_BACKGROUND_NOISE_H_ 12 #define WEBRTC_MODULES_AUDIO_CODING_NETEQ_BACKGROUND_NOISE_H_ 13 14 #include <string.h> // size_t 15 16 #include "webrtc/base/constructormagic.h" 17 #include "webrtc/base/scoped_ptr.h" 18 #include "webrtc/modules/audio_coding/neteq/audio_multi_vector.h" 19 #include "webrtc/modules/audio_coding/neteq/include/neteq.h" 20 #include "webrtc/typedefs.h" 21 22 namespace webrtc { 23 24 // Forward declarations. 25 class PostDecodeVad; 26 27 // This class handles estimation of background noise parameters. 28 class BackgroundNoise { 29 public: 30 // TODO(hlundin): For 48 kHz support, increase kMaxLpcOrder to 10. 31 // Will work anyway, but probably sound a little worse. 32 static const size_t kMaxLpcOrder = 8; // 32000 / 8000 + 4. 33 34 explicit BackgroundNoise(size_t num_channels); 35 virtual ~BackgroundNoise(); 36 37 void Reset(); 38 39 // Updates the parameter estimates based on the signal currently in the 40 // |sync_buffer|, and on the latest decision in |vad| if it is running. 41 void Update(const AudioMultiVector& sync_buffer, 42 const PostDecodeVad& vad); 43 44 // Returns |energy_| for |channel|. 45 int32_t Energy(size_t channel) const; 46 47 // Sets the value of |mute_factor_| for |channel| to |value|. 48 void SetMuteFactor(size_t channel, int16_t value); 49 50 // Returns |mute_factor_| for |channel|. 51 int16_t MuteFactor(size_t channel) const; 52 53 // Returns a pointer to |filter_| for |channel|. 54 const int16_t* Filter(size_t channel) const; 55 56 // Returns a pointer to |filter_state_| for |channel|. 57 const int16_t* FilterState(size_t channel) const; 58 59 // Copies |length| elements from |input| to the filter state. Will not copy 60 // more than |kMaxLpcOrder| elements. 61 void SetFilterState(size_t channel, const int16_t* input, size_t length); 62 63 // Returns |scale_| for |channel|. 64 int16_t Scale(size_t channel) const; 65 66 // Returns |scale_shift_| for |channel|. 67 int16_t ScaleShift(size_t channel) const; 68 69 // Accessors. initialized()70 bool initialized() const { return initialized_; } mode()71 NetEq::BackgroundNoiseMode mode() const { return mode_; } 72 73 // Sets the mode of the background noise playout for cases when there is long 74 // duration of packet loss. set_mode(NetEq::BackgroundNoiseMode mode)75 void set_mode(NetEq::BackgroundNoiseMode mode) { mode_ = mode; } 76 77 private: 78 static const int kThresholdIncrement = 229; // 0.0035 in Q16. 79 static const size_t kVecLen = 256; 80 static const int kLogVecLen = 8; // log2(kVecLen). 81 static const size_t kResidualLength = 64; 82 static const int16_t kLogResidualLength = 6; // log2(kResidualLength) 83 84 struct ChannelParameters { 85 // Constructor. ChannelParametersChannelParameters86 ChannelParameters() { 87 Reset(); 88 } 89 ResetChannelParameters90 void Reset() { 91 energy = 2500; 92 max_energy = 0; 93 energy_update_threshold = 500000; 94 low_energy_update_threshold = 0; 95 memset(filter_state, 0, sizeof(filter_state)); 96 memset(filter, 0, sizeof(filter)); 97 filter[0] = 4096; 98 mute_factor = 0, 99 scale = 20000; 100 scale_shift = 24; 101 } 102 103 int32_t energy; 104 int32_t max_energy; 105 int32_t energy_update_threshold; 106 int32_t low_energy_update_threshold; 107 int16_t filter_state[kMaxLpcOrder]; 108 int16_t filter[kMaxLpcOrder + 1]; 109 int16_t mute_factor; 110 int16_t scale; 111 int16_t scale_shift; 112 }; 113 114 int32_t CalculateAutoCorrelation(const int16_t* signal, 115 size_t length, 116 int32_t* auto_correlation) const; 117 118 // Increments the energy threshold by a factor 1 + |kThresholdIncrement|. 119 void IncrementEnergyThreshold(size_t channel, int32_t sample_energy); 120 121 // Updates the filter parameters. 122 void SaveParameters(size_t channel, 123 const int16_t* lpc_coefficients, 124 const int16_t* filter_state, 125 int32_t sample_energy, 126 int32_t residual_energy); 127 128 size_t num_channels_; 129 rtc::scoped_ptr<ChannelParameters[]> channel_parameters_; 130 bool initialized_; 131 NetEq::BackgroundNoiseMode mode_; 132 133 RTC_DISALLOW_COPY_AND_ASSIGN(BackgroundNoise); 134 }; 135 136 } // namespace webrtc 137 #endif // WEBRTC_MODULES_AUDIO_CODING_NETEQ_BACKGROUND_NOISE_H_ 138