1 files changed, 96 insertions, 0 deletions
diff --git a/third_party/libwebrtc/modules/audio_processing/capture_levels_adjuster/capture_levels_adjuster.cc b/third_party/libwebrtc/modules/audio_processing/capture_levels_adjuster/capture_levels_adjuster.cc
new file mode 100644
index 0000000000..dfda582915
--- /dev/null
+++ b/third_party/libwebrtc/modules/audio_processing/capture_levels_adjuster/capture_levels_adjuster.cc
@@ -0,0 +1,96 @@
+/*
+ *  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.
+ */
+#include "modules/audio_processing/capture_levels_adjuster/capture_levels_adjuster.h"
+
+#include "modules/audio_processing/audio_buffer.h"
+#include "rtc_base/checks.h"
+#include "rtc_base/numerics/safe_minmax.h"
+
+namespace webrtc {
+
+namespace {
+
+constexpr int kMinAnalogMicGainLevel = 0;
+constexpr int kMaxAnalogMicGainLevel = 255;
+
+float ComputeLevelBasedGain(int emulated_analog_mic_gain_level) {
+  static_assert(
+      kMinAnalogMicGainLevel == 0,
+      "The minimum gain level must be 0 for the maths below to work.");
+  static_assert(kMaxAnalogMicGainLevel > 0,
+                "The minimum gain level must be larger than 0 for the maths "
+                "below to work.");
+  constexpr float kGainToLevelMultiplier = 1.f / kMaxAnalogMicGainLevel;
+
+  RTC_DCHECK_GE(emulated_analog_mic_gain_level, kMinAnalogMicGainLevel);
+  RTC_DCHECK_LE(emulated_analog_mic_gain_level, kMaxAnalogMicGainLevel);
+  return kGainToLevelMultiplier * emulated_analog_mic_gain_level;
+}
+
+float ComputePreGain(float pre_gain,
+                     int emulated_analog_mic_gain_level,
+                     bool emulated_analog_mic_gain_enabled) {
+  return emulated_analog_mic_gain_enabled
+             ? pre_gain * ComputeLevelBasedGain(emulated_analog_mic_gain_level)
+             : pre_gain;
+}
+
+}  // namespace
+
+CaptureLevelsAdjuster::CaptureLevelsAdjuster(
+    bool emulated_analog_mic_gain_enabled,
+    int emulated_analog_mic_gain_level,
+    float pre_gain,
+    float post_gain)
+    : emulated_analog_mic_gain_enabled_(emulated_analog_mic_gain_enabled),
+      emulated_analog_mic_gain_level_(emulated_analog_mic_gain_level),
+      pre_gain_(pre_gain),
+      pre_adjustment_gain_(ComputePreGain(pre_gain_,
+                                          emulated_analog_mic_gain_level_,
+                                          emulated_analog_mic_gain_enabled_)),
+      pre_scaler_(pre_adjustment_gain_),
+      post_scaler_(post_gain) {}
+
+void CaptureLevelsAdjuster::ApplyPreLevelAdjustment(AudioBuffer& audio_buffer) {
+  pre_scaler_.Process(audio_buffer);
+}
+
+void CaptureLevelsAdjuster::ApplyPostLevelAdjustment(
+    AudioBuffer& audio_buffer) {
+  post_scaler_.Process(audio_buffer);
+}
+
+void CaptureLevelsAdjuster::SetPreGain(float pre_gain) {
+  pre_gain_ = pre_gain;
+  UpdatePreAdjustmentGain();
+}
+
+void CaptureLevelsAdjuster::SetPostGain(float post_gain) {
+  post_scaler_.SetGain(post_gain);
+}
+
+void CaptureLevelsAdjuster::SetAnalogMicGainLevel(int level) {
+  RTC_DCHECK_GE(level, kMinAnalogMicGainLevel);
+  RTC_DCHECK_LE(level, kMaxAnalogMicGainLevel);
+  int clamped_level =
+      rtc::SafeClamp(level, kMinAnalogMicGainLevel, kMaxAnalogMicGainLevel);
+
+  emulated_analog_mic_gain_level_ = clamped_level;
+  UpdatePreAdjustmentGain();
+}
+
+void CaptureLevelsAdjuster::UpdatePreAdjustmentGain() {
+  pre_adjustment_gain_ =
+      ComputePreGain(pre_gain_, emulated_analog_mic_gain_level_,
+                     emulated_analog_mic_gain_enabled_);
+  pre_scaler_.SetGain(pre_adjustment_gain_);
+}
+
+}  // namespace webrtc