1 /* 2 * Copyright (c) 2018 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 MODULES_AUDIO_PROCESSING_AGC2_INTERPOLATED_GAIN_CURVE_H_ 12 #define MODULES_AUDIO_PROCESSING_AGC2_INTERPOLATED_GAIN_CURVE_H_ 13 14 #include <array> 15 16 #include "absl/strings/string_view.h" 17 #include "modules/audio_processing/agc2/agc2_common.h" 18 #include "rtc_base/gtest_prod_util.h" 19 #include "system_wrappers/include/metrics.h" 20 21 namespace webrtc { 22 23 class ApmDataDumper; 24 25 constexpr float kInputLevelScalingFactor = 32768.0f; 26 27 // Defined as DbfsToLinear(kLimiterMaxInputLevelDbFs) 28 constexpr float kMaxInputLevelLinear = static_cast<float>(36766.300710566735); 29 30 // Interpolated gain curve using under-approximation to avoid saturation. 31 // 32 // The goal of this class is allowing fast look ups to get an accurate 33 // estimates of the gain to apply given an estimated input level. 34 class InterpolatedGainCurve { 35 public: 36 enum class GainCurveRegion { 37 kIdentity = 0, 38 kKnee = 1, 39 kLimiter = 2, 40 kSaturation = 3 41 }; 42 43 struct Stats { 44 // Region in which the output level equals the input one. 45 size_t look_ups_identity_region = 0; 46 // Smoothing between the identity and the limiter regions. 47 size_t look_ups_knee_region = 0; 48 // Limiter region in which the output and input levels are linearly related. 49 size_t look_ups_limiter_region = 0; 50 // Region in which saturation may occur since the input level is beyond the 51 // maximum expected by the limiter. 52 size_t look_ups_saturation_region = 0; 53 // True if stats have been populated. 54 bool available = false; 55 56 // The current region, and for how many frames the level has been 57 // in that region. 58 GainCurveRegion region = GainCurveRegion::kIdentity; 59 int64_t region_duration_frames = 0; 60 }; 61 62 InterpolatedGainCurve(ApmDataDumper* apm_data_dumper, 63 absl::string_view histogram_name_prefix); 64 ~InterpolatedGainCurve(); 65 66 InterpolatedGainCurve(const InterpolatedGainCurve&) = delete; 67 InterpolatedGainCurve& operator=(const InterpolatedGainCurve&) = delete; 68 get_stats()69 Stats get_stats() const { return stats_; } 70 71 // Given a non-negative input level (linear scale), a scalar factor to apply 72 // to a sub-frame is returned. 73 // Levels above kLimiterMaxInputLevelDbFs will be reduced to 0 dBFS 74 // after applying this gain 75 float LookUpGainToApply(float input_level) const; 76 77 private: 78 // For comparing 'approximation_params_*_' with ones computed by 79 // ComputeInterpolatedGainCurve. 80 FRIEND_TEST_ALL_PREFIXES(GainController2InterpolatedGainCurve, 81 CheckApproximationParams); 82 83 struct RegionLogger { 84 metrics::Histogram* identity_histogram; 85 metrics::Histogram* knee_histogram; 86 metrics::Histogram* limiter_histogram; 87 metrics::Histogram* saturation_histogram; 88 89 RegionLogger(absl::string_view identity_histogram_name, 90 absl::string_view knee_histogram_name, 91 absl::string_view limiter_histogram_name, 92 absl::string_view saturation_histogram_name); 93 94 ~RegionLogger(); 95 96 void LogRegionStats(const InterpolatedGainCurve::Stats& stats) const; 97 } region_logger_; 98 99 void UpdateStats(float input_level) const; 100 101 ApmDataDumper* const apm_data_dumper_; 102 103 static constexpr std::array<float, kInterpolatedGainCurveTotalPoints> 104 approximation_params_x_ = { 105 {30057.296875, 30148.986328125, 30240.67578125, 30424.052734375, 106 30607.4296875, 30790.806640625, 30974.18359375, 31157.560546875, 107 31340.939453125, 31524.31640625, 31707.693359375, 31891.0703125, 108 32074.447265625, 32257.82421875, 32441.201171875, 32624.580078125, 109 32807.95703125, 32991.33203125, 33174.7109375, 33358.08984375, 110 33541.46484375, 33724.84375, 33819.53515625, 34009.5390625, 111 34200.05859375, 34389.81640625, 34674.48828125, 35054.375, 112 35434.86328125, 35814.81640625, 36195.16796875, 36575.03125}}; 113 static constexpr std::array<float, kInterpolatedGainCurveTotalPoints> 114 approximation_params_m_ = { 115 {-3.515235675877192989e-07, -1.050251626111275982e-06, 116 -2.085213736791047268e-06, -3.443004743530764244e-06, 117 -4.773849468620028347e-06, -6.077375928725814447e-06, 118 -7.353257842623861507e-06, -8.601219633419532329e-06, 119 -9.821013009059242904e-06, -1.101243378798244521e-05, 120 -1.217532644659513608e-05, -1.330956911260727793e-05, 121 -1.441507538402220234e-05, -1.549179251014720649e-05, 122 -1.653970684856176376e-05, -1.755882840370759368e-05, 123 -1.854918446042574942e-05, -1.951086778717581183e-05, 124 -2.044398024736437947e-05, -2.1348627342376858e-05, 125 -2.222496914328075945e-05, -2.265374678245279938e-05, 126 -2.242570917587727308e-05, -2.220122041762806475e-05, 127 -2.19802095671184361e-05, -2.176260204578284174e-05, 128 -2.133731686626560986e-05, -2.092481918225530535e-05, 129 -2.052459603874012828e-05, -2.013615448959171772e-05, 130 -1.975903069251216948e-05, -1.939277899509761482e-05}}; 131 132 static constexpr std::array<float, kInterpolatedGainCurveTotalPoints> 133 approximation_params_q_ = { 134 {1.010565876960754395, 1.031631827354431152, 1.062929749488830566, 135 1.104239225387573242, 1.144973039627075195, 1.185109615325927734, 136 1.224629044532775879, 1.263512492179870605, 1.301741957664489746, 137 1.339300632476806641, 1.376173257827758789, 1.412345528602600098, 138 1.447803974151611328, 1.482536554336547852, 1.516532182693481445, 139 1.549780607223510742, 1.582272171974182129, 1.613999366760253906, 140 1.644955039024353027, 1.675132393836975098, 1.704526185989379883, 141 1.718986630439758301, 1.711274504661560059, 1.703639745712280273, 142 1.696081161499023438, 1.688597679138183594, 1.673851132392883301, 143 1.659391283988952637, 1.645209431648254395, 1.631297469139099121, 144 1.617647409439086914, 1.604251742362976074}}; 145 146 // Stats. 147 mutable Stats stats_; 148 }; 149 150 } // namespace webrtc 151 152 #endif // MODULES_AUDIO_PROCESSING_AGC2_INTERPOLATED_GAIN_CURVE_H_ 153