1 /* 2 * Copyright (c) 2021 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 #ifndef MODULES_AUDIO_PROCESSING_CAPTURE_LEVELS_ADJUSTER_CAPTURE_LEVELS_ADJUSTER_H_ 11 #define MODULES_AUDIO_PROCESSING_CAPTURE_LEVELS_ADJUSTER_CAPTURE_LEVELS_ADJUSTER_H_ 12 13 #include <stddef.h> 14 15 #include "modules/audio_processing/audio_buffer.h" 16 #include "modules/audio_processing/capture_levels_adjuster/audio_samples_scaler.h" 17 18 namespace webrtc { 19 20 // Adjusts the level of the capture signal before and after all capture-side 21 // processing is done using a combination of explicitly specified gains 22 // and an emulated analog gain functionality where a specified analog level 23 // results in an additional gain. The pre-adjustment is achieved by combining 24 // the gain value `pre_gain` and the level `emulated_analog_mic_gain_level` to 25 // form a combined gain of `pre_gain`*`emulated_analog_mic_gain_level`/255 which 26 // is multiplied to each sample. The intention of the 27 // `emulated_analog_mic_gain_level` is to be controlled by the analog AGC 28 // functionality and to produce an emulated analog mic gain equal to 29 // `emulated_analog_mic_gain_level`/255. The post level adjustment is achieved 30 // by multiplying each sample with the value of `post_gain`. Any changes in the 31 // gains take are done smoothly over one frame and the scaled samples are 32 // clamped to fit into the allowed S16 sample range. 33 class CaptureLevelsAdjuster { 34 public: 35 // C-tor. The values for the level and the gains must fulfill 36 // 0 <= emulated_analog_mic_gain_level <= 255. 37 // 0.f <= pre_gain. 38 // 0.f <= post_gain. 39 CaptureLevelsAdjuster(bool emulated_analog_mic_gain_enabled, 40 int emulated_analog_mic_gain_level, 41 float pre_gain, 42 float post_gain); 43 CaptureLevelsAdjuster(const CaptureLevelsAdjuster&) = delete; 44 CaptureLevelsAdjuster& operator=(const CaptureLevelsAdjuster&) = delete; 45 46 // Adjusts the level of the signal. This should be called before any of the 47 // other processing is performed. 48 void ApplyPreLevelAdjustment(AudioBuffer& audio_buffer); 49 50 // Adjusts the level of the signal. This should be called after all of the 51 // other processing have been performed. 52 void ApplyPostLevelAdjustment(AudioBuffer& audio_buffer); 53 54 // Sets the gain to apply to each sample before any of the other processing is 55 // performed. 56 void SetPreGain(float pre_gain); 57 58 // Returns the total pre-adjustment gain applied, comprising both the pre_gain 59 // as well as the gain from the emulated analog mic, to each sample before any 60 // of the other processing is performed. GetPreAdjustmentGain()61 float GetPreAdjustmentGain() const { return pre_adjustment_gain_; } 62 63 // Sets the gain to apply to each sample after all of the other processing 64 // have been performed. 65 void SetPostGain(float post_gain); 66 67 // Sets the analog gain level to use for the emulated analog gain. 68 // `level` must be in the range [0...255]. 69 void SetAnalogMicGainLevel(int level); 70 71 // Returns the current analog gain level used for the emulated analog gain. GetAnalogMicGainLevel()72 int GetAnalogMicGainLevel() const { return emulated_analog_mic_gain_level_; } 73 74 private: 75 // Updates the value of `pre_adjustment_gain_` based on the supplied values 76 // for `pre_gain` and `emulated_analog_mic_gain_level_`. 77 void UpdatePreAdjustmentGain(); 78 79 const bool emulated_analog_mic_gain_enabled_; 80 int emulated_analog_mic_gain_level_; 81 float pre_gain_; 82 float pre_adjustment_gain_; 83 AudioSamplesScaler pre_scaler_; 84 AudioSamplesScaler post_scaler_; 85 }; 86 } // namespace webrtc 87 88 #endif // MODULES_AUDIO_PROCESSING_CAPTURE_LEVELS_ADJUSTER_CAPTURE_LEVELS_ADJUSTER_H_ 89