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diff --git a/third_party/libwebrtc/modules/audio_processing/capture_levels_adjuster/capture_levels_adjuster.h b/third_party/libwebrtc/modules/audio_processing/capture_levels_adjuster/capture_levels_adjuster.h
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+/*
+ *  Copyright (c) 2021 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_PROCESSING_CAPTURE_LEVELS_ADJUSTER_CAPTURE_LEVELS_ADJUSTER_H_
+#define MODULES_AUDIO_PROCESSING_CAPTURE_LEVELS_ADJUSTER_CAPTURE_LEVELS_ADJUSTER_H_
+
+#include <stddef.h>
+
+#include "modules/audio_processing/audio_buffer.h"
+#include "modules/audio_processing/capture_levels_adjuster/audio_samples_scaler.h"
+
+namespace webrtc {
+
+// Adjusts the level of the capture signal before and after all capture-side
+// processing is done using a combination of explicitly specified gains
+// and an emulated analog gain functionality where a specified analog level
+// results in an additional gain. The pre-adjustment is achieved by combining
+// the gain value `pre_gain` and the level `emulated_analog_mic_gain_level` to
+// form a combined gain of `pre_gain`*`emulated_analog_mic_gain_level`/255 which
+// is multiplied to each sample. The intention of the
+// `emulated_analog_mic_gain_level` is to be controlled by the analog AGC
+// functionality and to produce an emulated analog mic gain equal to
+// `emulated_analog_mic_gain_level`/255. The post level adjustment is achieved
+// by multiplying each sample with the value of `post_gain`. Any changes in the
+// gains take are done smoothly over one frame and the scaled samples are
+// clamped to fit into the allowed S16 sample range.
+class CaptureLevelsAdjuster {
+ public:
+  // C-tor. The values for the level and the gains must fulfill
+  // 0 <= emulated_analog_mic_gain_level <= 255.
+  // 0.f <= pre_gain.
+  // 0.f <= post_gain.
+  CaptureLevelsAdjuster(bool emulated_analog_mic_gain_enabled,
+                        int emulated_analog_mic_gain_level,
+                        float pre_gain,
+                        float post_gain);
+  CaptureLevelsAdjuster(const CaptureLevelsAdjuster&) = delete;
+  CaptureLevelsAdjuster& operator=(const CaptureLevelsAdjuster&) = delete;
+
+  // Adjusts the level of the signal. This should be called before any of the
+  // other processing is performed.
+  void ApplyPreLevelAdjustment(AudioBuffer& audio_buffer);
+
+  // Adjusts the level of the signal. This should be called after all of the
+  // other processing have been performed.
+  void ApplyPostLevelAdjustment(AudioBuffer& audio_buffer);
+
+  // Sets the gain to apply to each sample before any of the other processing is
+  // performed.
+  void SetPreGain(float pre_gain);
+
+  // Returns the total pre-adjustment gain applied, comprising both the pre_gain
+  // as well as the gain from the emulated analog mic, to each sample before any
+  // of the other processing is performed.
+  float GetPreAdjustmentGain() const { return pre_adjustment_gain_; }
+
+  // Sets the gain to apply to each sample after all of the other processing
+  // have been performed.
+  void SetPostGain(float post_gain);
+
+  // Sets the analog gain level to use for the emulated analog gain.
+  // `level` must be in the range [0...255].
+  void SetAnalogMicGainLevel(int level);
+
+  // Returns the current analog gain level used for the emulated analog gain.
+  int GetAnalogMicGainLevel() const { return emulated_analog_mic_gain_level_; }
+
+ private:
+  // Updates the value of `pre_adjustment_gain_` based on the supplied values
+  // for `pre_gain` and `emulated_analog_mic_gain_level_`.
+  void UpdatePreAdjustmentGain();
+
+  const bool emulated_analog_mic_gain_enabled_;
+  int emulated_analog_mic_gain_level_;
+  float pre_gain_;
+  float pre_adjustment_gain_;
+  AudioSamplesScaler pre_scaler_;
+  AudioSamplesScaler post_scaler_;
+};
+}  // namespace webrtc
+
+#endif  // MODULES_AUDIO_PROCESSING_CAPTURE_LEVELS_ADJUSTER_CAPTURE_LEVELS_ADJUSTER_H_