interpolated_gain_curve.h (6555B)
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 #include <cstddef> 16 #include <cstdint> 17 18 #include "absl/strings/string_view.h" 19 #include "modules/audio_processing/agc2/agc2_common.h" 20 #include "rtc_base/gtest_prod_util.h" 21 #include "system_wrappers/include/metrics.h" 22 23 namespace webrtc { 24 25 class ApmDataDumper; 26 27 constexpr float kInputLevelScalingFactor = 32768.0f; 28 29 // Defined as DbfsToLinear(kLimiterMaxInputLevelDbFs) 30 constexpr float kMaxInputLevelLinear = static_cast<float>(36766.300710566735); 31 32 // Interpolated gain curve using under-approximation to avoid saturation. 33 // 34 // The goal of this class is allowing fast look ups to get an accurate 35 // estimates of the gain to apply given an estimated input level. 36 class InterpolatedGainCurve { 37 public: 38 enum class GainCurveRegion { 39 kIdentity = 0, 40 kKnee = 1, 41 kLimiter = 2, 42 kSaturation = 3 43 }; 44 45 struct Stats { 46 // Region in which the output level equals the input one. 47 size_t look_ups_identity_region = 0; 48 // Smoothing between the identity and the limiter regions. 49 size_t look_ups_knee_region = 0; 50 // Limiter region in which the output and input levels are linearly related. 51 size_t look_ups_limiter_region = 0; 52 // Region in which saturation may occur since the input level is beyond the 53 // maximum expected by the limiter. 54 size_t look_ups_saturation_region = 0; 55 // True if stats have been populated. 56 bool available = false; 57 58 // The current region, and for how many frames the level has been 59 // in that region. 60 GainCurveRegion region = GainCurveRegion::kIdentity; 61 int64_t region_duration_frames = 0; 62 }; 63 64 InterpolatedGainCurve(ApmDataDumper* apm_data_dumper, 65 absl::string_view histogram_name_prefix); 66 ~InterpolatedGainCurve(); 67 68 InterpolatedGainCurve(const InterpolatedGainCurve&) = delete; 69 InterpolatedGainCurve& operator=(const InterpolatedGainCurve&) = delete; 70 71 Stats get_stats() const { return stats_; } 72 73 // Given a non-negative input level (linear scale), a scalar factor to apply 74 // to a sub-frame is returned. 75 // Levels above kLimiterMaxInputLevelDbFs will be reduced to 0 dBFS 76 // after applying this gain 77 float LookUpGainToApply(float input_level) const; 78 79 private: 80 // For comparing 'approximation_params_*_' with ones computed by 81 // ComputeInterpolatedGainCurve. 82 FRIEND_TEST_ALL_PREFIXES(GainController2InterpolatedGainCurve, 83 CheckApproximationParams); 84 85 struct RegionLogger { 86 metrics::Histogram* identity_histogram; 87 metrics::Histogram* knee_histogram; 88 metrics::Histogram* limiter_histogram; 89 metrics::Histogram* saturation_histogram; 90 91 RegionLogger(absl::string_view identity_histogram_name, 92 absl::string_view knee_histogram_name, 93 absl::string_view limiter_histogram_name, 94 absl::string_view saturation_histogram_name); 95 96 ~RegionLogger(); 97 98 void LogRegionStats(const InterpolatedGainCurve::Stats& stats) const; 99 } region_logger_; 100 101 void UpdateStats(float input_level) const; 102 103 ApmDataDumper* const apm_data_dumper_; 104 105 static constexpr std::array<float, kInterpolatedGainCurveTotalPoints> 106 approximation_params_x_ = { 107 {30057.296875, 30148.986328125, 30240.67578125, 30424.052734375, 108 30607.4296875, 30790.806640625, 30974.18359375, 31157.560546875, 109 31340.939453125, 31524.31640625, 31707.693359375, 31891.0703125, 110 32074.447265625, 32257.82421875, 32441.201171875, 32624.580078125, 111 32807.95703125, 32991.33203125, 33174.7109375, 33358.08984375, 112 33541.46484375, 33724.84375, 33819.53515625, 34009.5390625, 113 34200.05859375, 34389.81640625, 34674.48828125, 35054.375, 114 35434.86328125, 35814.81640625, 36195.16796875, 36575.03125}}; 115 static constexpr std::array<float, kInterpolatedGainCurveTotalPoints> 116 approximation_params_m_ = { 117 {-3.515235675877192989e-07, -1.050251626111275982e-06, 118 -2.085213736791047268e-06, -3.443004743530764244e-06, 119 -4.773849468620028347e-06, -6.077375928725814447e-06, 120 -7.353257842623861507e-06, -8.601219633419532329e-06, 121 -9.821013009059242904e-06, -1.101243378798244521e-05, 122 -1.217532644659513608e-05, -1.330956911260727793e-05, 123 -1.441507538402220234e-05, -1.549179251014720649e-05, 124 -1.653970684856176376e-05, -1.755882840370759368e-05, 125 -1.854918446042574942e-05, -1.951086778717581183e-05, 126 -2.044398024736437947e-05, -2.1348627342376858e-05, 127 -2.222496914328075945e-05, -2.265374678245279938e-05, 128 -2.242570917587727308e-05, -2.220122041762806475e-05, 129 -2.19802095671184361e-05, -2.176260204578284174e-05, 130 -2.133731686626560986e-05, -2.092481918225530535e-05, 131 -2.052459603874012828e-05, -2.013615448959171772e-05, 132 -1.975903069251216948e-05, -1.939277899509761482e-05}}; 133 134 static constexpr std::array<float, kInterpolatedGainCurveTotalPoints> 135 approximation_params_q_ = { 136 {1.010565876960754395, 1.031631827354431152, 1.062929749488830566, 137 1.104239225387573242, 1.144973039627075195, 1.185109615325927734, 138 1.224629044532775879, 1.263512492179870605, 1.301741957664489746, 139 1.339300632476806641, 1.376173257827758789, 1.412345528602600098, 140 1.447803974151611328, 1.482536554336547852, 1.516532182693481445, 141 1.549780607223510742, 1.582272171974182129, 1.613999366760253906, 142 1.644955039024353027, 1.675132393836975098, 1.704526185989379883, 143 1.718986630439758301, 1.711274504661560059, 1.703639745712280273, 144 1.696081161499023438, 1.688597679138183594, 1.673851132392883301, 145 1.659391283988952637, 1.645209431648254395, 1.631297469139099121, 146 1.617647409439086914, 1.604251742362976074}}; 147 148 // Stats. 149 mutable Stats stats_; 150 }; 151 152 } // namespace webrtc 153 154 #endif // MODULES_AUDIO_PROCESSING_AGC2_INTERPOLATED_GAIN_CURVE_H_