Revert "APM: rename `AnalogGainStatsReporter` to `InputVolumeStatsReporter`"

This reverts commit b5319fabeeda4ffbf58f28f4ee3d5c7c3868fb3b.

Reason for revert: audioproc_f crash 

Original change's description:
> APM: rename `AnalogGainStatsReporter` to `InputVolumeStatsReporter`
>
> Adopt the new naming convention, which replaces "analog gain" and
> "mic level" with "input volume", in the input volume stats reporter.
>
> Bug: webrtc:7494
> Change-Id: Ia24876151f51dd1dcc4e4f9db56c64d11ae3b442
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/279840
> Reviewed-by: Hanna Silen <silen@webrtc.org>
> Commit-Queue: Alessio Bazzica <alessiob@webrtc.org>
> Cr-Commit-Position: refs/heads/main@{#38467}

Bug: webrtc:7494
Change-Id: Ia943a57c93fc77eb8450fab17961e60774e10f02
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/280600
Bot-Commit: rubber-stamper@appspot.gserviceaccount.com <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Alessio Bazzica <alessiob@webrtc.org>
Auto-Submit: Alessio Bazzica <alessiob@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#38478}
diff --git a/modules/audio_processing/agc2/input_volume_stats_reporter.cc b/modules/audio_processing/agc2/input_volume_stats_reporter.cc
index 4a8b016..b2c1831 100644
--- a/modules/audio_processing/agc2/input_volume_stats_reporter.cc
+++ b/modules/audio_processing/agc2/input_volume_stats_reporter.cc
@@ -20,9 +20,9 @@
 namespace {
 
 constexpr int kFramesIn60Seconds = 6000;
-constexpr int kMinInputVolume = 0;
-constexpr int kMaxInputVolume = 255;
-constexpr int kMaxUpdate = kMaxInputVolume - kMinInputVolume;
+constexpr int kMinGain = 0;
+constexpr int kMaxGain = 255;
+constexpr int kMaxUpdate = kMaxGain - kMinGain;
 
 float ComputeAverageUpdate(int sum_updates, int num_updates) {
   RTC_DCHECK_GE(sum_updates, 0);
@@ -37,50 +37,59 @@
 }
 }  // namespace
 
-InputVolumeStatsReporter::InputVolumeStatsReporter() = default;
+AnalogGainStatsReporter::AnalogGainStatsReporter() = default;
 
-InputVolumeStatsReporter::~InputVolumeStatsReporter() = default;
+AnalogGainStatsReporter::~AnalogGainStatsReporter() = default;
 
-void InputVolumeStatsReporter::UpdateStatistics(int input_volume) {
-  RTC_DCHECK_GE(input_volume, kMinInputVolume);
-  RTC_DCHECK_LE(input_volume, kMaxInputVolume);
-  if (previous_input_volume_.has_value() &&
-      input_volume != previous_input_volume_.value()) {
-    const int volume_change = input_volume - previous_input_volume_.value();
-    if (volume_change < 0) {
-      ++volume_update_stats_.num_decreases;
-      volume_update_stats_.sum_decreases -= volume_change;
+void AnalogGainStatsReporter::UpdateStatistics(int analog_mic_level) {
+  RTC_DCHECK_GE(analog_mic_level, kMinGain);
+  RTC_DCHECK_LE(analog_mic_level, kMaxGain);
+  if (previous_analog_mic_level_.has_value() &&
+      analog_mic_level != previous_analog_mic_level_.value()) {
+    const int level_change =
+        analog_mic_level - previous_analog_mic_level_.value();
+    if (level_change < 0) {
+      ++level_update_stats_.num_decreases;
+      level_update_stats_.sum_decreases -= level_change;
     } else {
-      ++volume_update_stats_.num_increases;
-      volume_update_stats_.sum_increases += volume_change;
+      ++level_update_stats_.num_increases;
+      level_update_stats_.sum_increases += level_change;
     }
   }
-  // Periodically log input volume change metrics.
-  if (++log_volume_update_stats_counter_ >= kFramesIn60Seconds) {
-    LogVolumeUpdateStats();
-    volume_update_stats_ = {};
-    log_volume_update_stats_counter_ = 0;
+  // Periodically log analog gain change metrics.
+  if (++log_level_update_stats_counter_ >= kFramesIn60Seconds) {
+    LogLevelUpdateStats();
+    level_update_stats_ = {};
+    log_level_update_stats_counter_ = 0;
   }
-  previous_input_volume_ = input_volume;
+  previous_analog_mic_level_ = analog_mic_level;
 }
 
-void InputVolumeStatsReporter::LogVolumeUpdateStats() const {
+void AnalogGainStatsReporter::LogLevelUpdateStats() const {
   const float average_decrease = ComputeAverageUpdate(
-      volume_update_stats_.sum_decreases, volume_update_stats_.num_decreases);
+      level_update_stats_.sum_decreases, level_update_stats_.num_decreases);
   const float average_increase = ComputeAverageUpdate(
-      volume_update_stats_.sum_increases, volume_update_stats_.num_increases);
+      level_update_stats_.sum_increases, level_update_stats_.num_increases);
   const int num_updates =
-      volume_update_stats_.num_decreases + volume_update_stats_.num_increases;
+      level_update_stats_.num_decreases + level_update_stats_.num_increases;
   const float average_update = ComputeAverageUpdate(
-      volume_update_stats_.sum_decreases + volume_update_stats_.sum_increases,
+      level_update_stats_.sum_decreases + level_update_stats_.sum_increases,
       num_updates);
+  RTC_DLOG(LS_INFO) << "Analog gain update rate: "
+                    << "num_updates=" << num_updates
+                    << ", num_decreases=" << level_update_stats_.num_decreases
+                    << ", num_increases=" << level_update_stats_.num_increases;
+  RTC_DLOG(LS_INFO) << "Analog gain update average: "
+                    << "average_update=" << average_update
+                    << ", average_decrease=" << average_decrease
+                    << ", average_increase=" << average_increase;
   RTC_HISTOGRAM_COUNTS_LINEAR(
       /*name=*/"WebRTC.Audio.ApmAnalogGainDecreaseRate",
-      /*sample=*/volume_update_stats_.num_decreases,
+      /*sample=*/level_update_stats_.num_decreases,
       /*min=*/1,
       /*max=*/kFramesIn60Seconds,
       /*bucket_count=*/50);
-  if (volume_update_stats_.num_decreases > 0) {
+  if (level_update_stats_.num_decreases > 0) {
     RTC_HISTOGRAM_COUNTS_LINEAR(
         /*name=*/"WebRTC.Audio.ApmAnalogGainDecreaseAverage",
         /*sample=*/average_decrease,
@@ -90,11 +99,11 @@
   }
   RTC_HISTOGRAM_COUNTS_LINEAR(
       /*name=*/"WebRTC.Audio.ApmAnalogGainIncreaseRate",
-      /*sample=*/volume_update_stats_.num_increases,
+      /*sample=*/level_update_stats_.num_increases,
       /*min=*/1,
       /*max=*/kFramesIn60Seconds,
       /*bucket_count=*/50);
-  if (volume_update_stats_.num_increases > 0) {
+  if (level_update_stats_.num_increases > 0) {
     RTC_HISTOGRAM_COUNTS_LINEAR(
         /*name=*/"WebRTC.Audio.ApmAnalogGainIncreaseAverage",
         /*sample=*/average_increase,
diff --git a/modules/audio_processing/agc2/input_volume_stats_reporter.h b/modules/audio_processing/agc2/input_volume_stats_reporter.h
index 0040754..fd048cf 100644
--- a/modules/audio_processing/agc2/input_volume_stats_reporter.h
+++ b/modules/audio_processing/agc2/input_volume_stats_reporter.h
@@ -16,49 +16,51 @@
 
 namespace webrtc {
 
-// Input volume statistics calculator. Computes aggregate stats based on the
-// framewise input volume observed by `UpdateStatistics()`. Periodically logs
-// the statistics into a histogram.
-class InputVolumeStatsReporter {
+// Analog gain statistics calculator. Computes aggregate stats based on the
+// framewise mic levels processed in `UpdateStatistics()`. Periodically logs the
+// statistics into a histogram.
+class AnalogGainStatsReporter {
  public:
-  InputVolumeStatsReporter();
-  InputVolumeStatsReporter(const InputVolumeStatsReporter&) = delete;
-  InputVolumeStatsReporter operator=(const InputVolumeStatsReporter&) = delete;
-  ~InputVolumeStatsReporter();
+  AnalogGainStatsReporter();
+  AnalogGainStatsReporter(const AnalogGainStatsReporter&) = delete;
+  AnalogGainStatsReporter operator=(const AnalogGainStatsReporter&) = delete;
+  ~AnalogGainStatsReporter();
 
-  // Updates the stats based on `input_volume`. Periodically logs the stats into
-  // a histogram.
-  void UpdateStatistics(int input_volume);
+  // Updates the stats based on the `analog_mic_level`. Periodically logs the
+  // stats into a histogram.
+  void UpdateStatistics(int analog_mic_level);
 
  private:
-  FRIEND_TEST_ALL_PREFIXES(InputVolumeStatsReporterTest,
-                           CheckVolumeUpdateStatsForEmptyStats);
-  FRIEND_TEST_ALL_PREFIXES(InputVolumeStatsReporterTest,
-                           CheckVolumeUpdateStatsAfterNoVolumeChange);
-  FRIEND_TEST_ALL_PREFIXES(InputVolumeStatsReporterTest,
-                           CheckVolumeUpdateStatsAfterVolumeIncrease);
-  FRIEND_TEST_ALL_PREFIXES(InputVolumeStatsReporterTest,
-                           CheckVolumeUpdateStatsAfterVolumeDecrease);
-  FRIEND_TEST_ALL_PREFIXES(InputVolumeStatsReporterTest,
-                           CheckVolumeUpdateStatsAfterReset);
+  FRIEND_TEST_ALL_PREFIXES(AnalogGainStatsReporterTest,
+                           CheckLevelUpdateStatsForEmptyStats);
+  FRIEND_TEST_ALL_PREFIXES(AnalogGainStatsReporterTest,
+                           CheckLevelUpdateStatsAfterNoGainChange);
+  FRIEND_TEST_ALL_PREFIXES(AnalogGainStatsReporterTest,
+                           CheckLevelUpdateStatsAfterGainIncrease);
+  FRIEND_TEST_ALL_PREFIXES(AnalogGainStatsReporterTest,
+                           CheckLevelUpdateStatsAfterGainDecrease);
+  FRIEND_TEST_ALL_PREFIXES(AnalogGainStatsReporterTest,
+                           CheckLevelUpdateStatsAfterReset);
 
-  // Stores input volume update stats to enable calculation of update rate and
-  // average update separately for volume increases and decreases.
-  struct VolumeUpdateStats {
+  // Stores analog gain update stats to enable calculation of update rate and
+  // average update separately for gain increases and decreases.
+  struct LevelUpdateStats {
     int num_decreases = 0;
     int num_increases = 0;
     int sum_decreases = 0;
     int sum_increases = 0;
-  } volume_update_stats_;
+  } level_update_stats_;
 
   // Returns a copy of the stored statistics. Use only for testing.
-  VolumeUpdateStats volume_update_stats() const { return volume_update_stats_; }
+  const LevelUpdateStats level_update_stats() const {
+    return level_update_stats_;
+  }
 
   // Computes aggregate stat and logs them into a histogram.
-  void LogVolumeUpdateStats() const;
+  void LogLevelUpdateStats() const;
 
-  int log_volume_update_stats_counter_ = 0;
-  absl::optional<int> previous_input_volume_ = absl::nullopt;
+  int log_level_update_stats_counter_ = 0;
+  absl::optional<int> previous_analog_mic_level_ = absl::nullopt;
 };
 }  // namespace webrtc
 
diff --git a/modules/audio_processing/agc2/input_volume_stats_reporter_unittest.cc b/modules/audio_processing/agc2/input_volume_stats_reporter_unittest.cc
index f8cd010..196b1e0 100644
--- a/modules/audio_processing/agc2/input_volume_stats_reporter_unittest.cc
+++ b/modules/audio_processing/agc2/input_volume_stats_reporter_unittest.cc
@@ -18,22 +18,22 @@
 
 constexpr int kFramesIn60Seconds = 6000;
 
-class InputVolumeStatsReporterTest : public ::testing::Test {
+class AnalogGainStatsReporterTest : public ::testing::Test {
  public:
-  InputVolumeStatsReporterTest() {}
+  AnalogGainStatsReporterTest() {}
 
  protected:
   void SetUp() override { metrics::Reset(); }
 };
 
-TEST_F(InputVolumeStatsReporterTest, CheckLogVolumeUpdateStatsEmpty) {
-  InputVolumeStatsReporter stats_reporter;
-  constexpr int kInputVolume = 10;
-  stats_reporter.UpdateStatistics(kInputVolume);
+TEST_F(AnalogGainStatsReporterTest, CheckLogLevelUpdateStatsEmpty) {
+  AnalogGainStatsReporter stats_reporter;
+  constexpr int kMicLevel = 10;
+  stats_reporter.UpdateStatistics(kMicLevel);
   // Update almost until the periodic logging and reset.
   for (int i = 0; i < kFramesIn60Seconds - 2; i += 2) {
-    stats_reporter.UpdateStatistics(kInputVolume + 2);
-    stats_reporter.UpdateStatistics(kInputVolume);
+    stats_reporter.UpdateStatistics(kMicLevel + 2);
+    stats_reporter.UpdateStatistics(kMicLevel);
   }
   EXPECT_METRIC_THAT(metrics::Samples("WebRTC.Audio.ApmAnalogGainUpdateRate"),
                      ::testing::ElementsAre());
@@ -52,19 +52,19 @@
       ::testing::ElementsAre());
 }
 
-TEST_F(InputVolumeStatsReporterTest, CheckLogVolumeUpdateStatsNotEmpty) {
-  InputVolumeStatsReporter stats_reporter;
-  constexpr int kInputVolume = 10;
-  stats_reporter.UpdateStatistics(kInputVolume);
+TEST_F(AnalogGainStatsReporterTest, CheckLogLevelUpdateStatsNotEmpty) {
+  AnalogGainStatsReporter stats_reporter;
+  constexpr int kMicLevel = 10;
+  stats_reporter.UpdateStatistics(kMicLevel);
   // Update until periodic logging.
   for (int i = 0; i < kFramesIn60Seconds; i += 2) {
-    stats_reporter.UpdateStatistics(kInputVolume + 2);
-    stats_reporter.UpdateStatistics(kInputVolume);
+    stats_reporter.UpdateStatistics(kMicLevel + 2);
+    stats_reporter.UpdateStatistics(kMicLevel);
   }
   // Update until periodic logging.
   for (int i = 0; i < kFramesIn60Seconds; i += 2) {
-    stats_reporter.UpdateStatistics(kInputVolume + 3);
-    stats_reporter.UpdateStatistics(kInputVolume);
+    stats_reporter.UpdateStatistics(kMicLevel + 3);
+    stats_reporter.UpdateStatistics(kMicLevel);
   }
   EXPECT_METRIC_THAT(
       metrics::Samples("WebRTC.Audio.ApmAnalogGainUpdateRate"),
@@ -89,80 +89,77 @@
 }
 }  // namespace
 
-TEST_F(InputVolumeStatsReporterTest, CheckVolumeUpdateStatsForEmptyStats) {
-  InputVolumeStatsReporter stats_reporter;
-  const auto& update_stats = stats_reporter.volume_update_stats();
+TEST_F(AnalogGainStatsReporterTest, CheckLevelUpdateStatsForEmptyStats) {
+  AnalogGainStatsReporter stats_reporter;
+  const auto& update_stats = stats_reporter.level_update_stats();
   EXPECT_EQ(update_stats.num_decreases, 0);
   EXPECT_EQ(update_stats.sum_decreases, 0);
   EXPECT_EQ(update_stats.num_increases, 0);
   EXPECT_EQ(update_stats.sum_increases, 0);
 }
 
-TEST_F(InputVolumeStatsReporterTest,
-       CheckVolumeUpdateStatsAfterNoVolumeChange) {
-  constexpr int kInputVolume = 10;
-  InputVolumeStatsReporter stats_reporter;
-  stats_reporter.UpdateStatistics(kInputVolume);
-  stats_reporter.UpdateStatistics(kInputVolume);
-  stats_reporter.UpdateStatistics(kInputVolume);
-  const auto& update_stats = stats_reporter.volume_update_stats();
+TEST_F(AnalogGainStatsReporterTest, CheckLevelUpdateStatsAfterNoGainChange) {
+  constexpr int kMicLevel = 10;
+  AnalogGainStatsReporter stats_reporter;
+  stats_reporter.UpdateStatistics(kMicLevel);
+  stats_reporter.UpdateStatistics(kMicLevel);
+  stats_reporter.UpdateStatistics(kMicLevel);
+  const auto& update_stats = stats_reporter.level_update_stats();
   EXPECT_EQ(update_stats.num_decreases, 0);
   EXPECT_EQ(update_stats.sum_decreases, 0);
   EXPECT_EQ(update_stats.num_increases, 0);
   EXPECT_EQ(update_stats.sum_increases, 0);
 }
 
-TEST_F(InputVolumeStatsReporterTest,
-       CheckVolumeUpdateStatsAfterVolumeIncrease) {
-  constexpr int kInputVolume = 10;
-  InputVolumeStatsReporter stats_reporter;
-  stats_reporter.UpdateStatistics(kInputVolume);
-  stats_reporter.UpdateStatistics(kInputVolume + 4);
-  stats_reporter.UpdateStatistics(kInputVolume + 5);
-  const auto& update_stats = stats_reporter.volume_update_stats();
+TEST_F(AnalogGainStatsReporterTest, CheckLevelUpdateStatsAfterGainIncrease) {
+  constexpr int kMicLevel = 10;
+  AnalogGainStatsReporter stats_reporter;
+  stats_reporter.UpdateStatistics(kMicLevel);
+  stats_reporter.UpdateStatistics(kMicLevel + 4);
+  stats_reporter.UpdateStatistics(kMicLevel + 5);
+  const auto& update_stats = stats_reporter.level_update_stats();
   EXPECT_EQ(update_stats.num_decreases, 0);
   EXPECT_EQ(update_stats.sum_decreases, 0);
   EXPECT_EQ(update_stats.num_increases, 2);
   EXPECT_EQ(update_stats.sum_increases, 5);
 }
 
-TEST_F(InputVolumeStatsReporterTest,
-       CheckVolumeUpdateStatsAfterVolumeDecrease) {
-  constexpr int kInputVolume = 10;
-  InputVolumeStatsReporter stats_reporter;
-  stats_reporter.UpdateStatistics(kInputVolume);
-  stats_reporter.UpdateStatistics(kInputVolume - 4);
-  stats_reporter.UpdateStatistics(kInputVolume - 5);
-  const auto& stats_update = stats_reporter.volume_update_stats();
+TEST_F(AnalogGainStatsReporterTest, CheckLevelUpdateStatsAfterGainDecrease) {
+  constexpr int kMicLevel = 10;
+  AnalogGainStatsReporter stats_reporter;
+  stats_reporter.UpdateStatistics(kMicLevel);
+  stats_reporter.UpdateStatistics(kMicLevel - 4);
+  stats_reporter.UpdateStatistics(kMicLevel - 5);
+  const auto& stats_update = stats_reporter.level_update_stats();
   EXPECT_EQ(stats_update.num_decreases, 2);
   EXPECT_EQ(stats_update.sum_decreases, 5);
   EXPECT_EQ(stats_update.num_increases, 0);
   EXPECT_EQ(stats_update.sum_increases, 0);
 }
 
-TEST_F(InputVolumeStatsReporterTest, CheckVolumeUpdateStatsAfterReset) {
-  InputVolumeStatsReporter stats_reporter;
-  constexpr int kInputVolume = 10;
-  stats_reporter.UpdateStatistics(kInputVolume);
+TEST_F(AnalogGainStatsReporterTest, CheckLevelUpdateStatsAfterReset) {
+  AnalogGainStatsReporter stats_reporter;
+  constexpr int kMicLevel = 10;
+  stats_reporter.UpdateStatistics(kMicLevel);
   // Update until the periodic reset.
   for (int i = 0; i < kFramesIn60Seconds - 2; i += 2) {
-    stats_reporter.UpdateStatistics(kInputVolume + 2);
-    stats_reporter.UpdateStatistics(kInputVolume);
+    stats_reporter.UpdateStatistics(kMicLevel + 2);
+    stats_reporter.UpdateStatistics(kMicLevel);
   }
-  const auto& stats_before_reset = stats_reporter.volume_update_stats();
+  const auto& stats_before_reset = stats_reporter.level_update_stats();
   EXPECT_EQ(stats_before_reset.num_decreases, kFramesIn60Seconds / 2 - 1);
   EXPECT_EQ(stats_before_reset.sum_decreases, kFramesIn60Seconds - 2);
   EXPECT_EQ(stats_before_reset.num_increases, kFramesIn60Seconds / 2 - 1);
   EXPECT_EQ(stats_before_reset.sum_increases, kFramesIn60Seconds - 2);
-  stats_reporter.UpdateStatistics(kInputVolume + 2);
-  const auto& stats_during_reset = stats_reporter.volume_update_stats();
+  stats_reporter.UpdateStatistics(kMicLevel + 2);
+  const auto& stats_during_reset = stats_reporter.level_update_stats();
   EXPECT_EQ(stats_during_reset.num_decreases, 0);
   EXPECT_EQ(stats_during_reset.sum_decreases, 0);
   EXPECT_EQ(stats_during_reset.num_increases, 0);
   EXPECT_EQ(stats_during_reset.sum_increases, 0);
-  stats_reporter.UpdateStatistics(kInputVolume);
-  stats_reporter.UpdateStatistics(kInputVolume + 3);
-  const auto& stats_after_reset = stats_reporter.volume_update_stats();
+  stats_reporter.UpdateStatistics(kMicLevel);
+  stats_reporter.UpdateStatistics(kMicLevel + 3);
+  const auto& stats_after_reset = stats_reporter.level_update_stats();
   EXPECT_EQ(stats_after_reset.num_decreases, 1);
   EXPECT_EQ(stats_after_reset.sum_decreases, 2);
   EXPECT_EQ(stats_after_reset.num_increases, 1);
diff --git a/modules/audio_processing/audio_processing_impl.cc b/modules/audio_processing/audio_processing_impl.cc
index 76e3804..1d588fe 100644
--- a/modules/audio_processing/audio_processing_impl.cc
+++ b/modules/audio_processing/audio_processing_impl.cc
@@ -1131,7 +1131,8 @@
   }
 
   if (capture_.applied_input_volume.has_value()) {
-    applied_input_volume_stats_reporter_.UpdateStatistics(
+    // Log the applied input volume only when available.
+    input_volume_stats_reporter_.UpdateStatistics(
         *capture_.applied_input_volume);
   }
 
diff --git a/modules/audio_processing/audio_processing_impl.h b/modules/audio_processing/audio_processing_impl.h
index bc582b5..3dfa8ce 100644
--- a/modules/audio_processing/audio_processing_impl.h
+++ b/modules/audio_processing/audio_processing_impl.h
@@ -539,7 +539,7 @@
   RmsLevel capture_output_rms_ RTC_GUARDED_BY(mutex_capture_);
   int capture_rms_interval_counter_ RTC_GUARDED_BY(mutex_capture_) = 0;
 
-  InputVolumeStatsReporter applied_input_volume_stats_reporter_
+  AnalogGainStatsReporter input_volume_stats_reporter_
       RTC_GUARDED_BY(mutex_capture_);
 
   // Lock protection not needed.