Improved tuning of the adaptive level controller.

webrtc/modules/audio_processing/level_controller/peak_level_estimator.cc

Index: webrtc/modules/audio_processing/level_controller/peak_level_estimator.cc
diff --git a/webrtc/modules/audio_processing/level_controller/peak_level_estimator.cc b/webrtc/modules/audio_processing/level_controller/peak_level_estimator.cc
index 9175717ab7c77271732b8398c60bef13694f1825..e65ae5bc80d609fc701b415ca3377b6ad2a7306c 100644
--- a/webrtc/modules/audio_processing/level_controller/peak_level_estimator.cc
+++ b/webrtc/modules/audio_processing/level_controller/peak_level_estimator.cc
@@ -13,6 +13,7 @@
 #include <algorithm>
 
 #include "webrtc/modules/audio_processing/audio_buffer.h"
+#include "webrtc/modules/audio_processing/level_controller/lc_constants.h"
 #include "webrtc/modules/audio_processing/logging/apm_data_dumper.h"
 
 namespace webrtc {
@@ -24,29 +25,34 @@ PeakLevelEstimator::PeakLevelEstimator() {
 PeakLevelEstimator::~PeakLevelEstimator() {}
 
 void PeakLevelEstimator::Initialize() {
-  peak_level_ = 1000.f;
+  peak_level_ = kTargetLcPeakLevel;
   hold_counter_ = 0;
+  initialization_phase_ = true;
 }
 
 float PeakLevelEstimator::Analyze(SignalClassifier::SignalType signal_type,
                                   float frame_peak_level) {
-  if (frame_peak_level > 0) {
-    if (peak_level_ < frame_peak_level) {
-      // Smoothly update the estimate upwards when the frame peak level is
-      // higher than the estimate.
-      peak_level_ += 0.1f * (frame_peak_level - peak_level_);
-      hold_counter_ = 100;
-    } else {
-      hold_counter_ = std::max(0, hold_counter_ - 1);
-
-      // When the signal is highly non-stationary, update the estimate slowly
-      // downwards if the estimate is lower than the frame peak level.
-      if (signal_type == SignalClassifier::SignalType::kHighlyNonStationary &&
-          hold_counter_ == 0) {
-        peak_level_ =
-            std::max(peak_level_ + 0.01f * (frame_peak_level - peak_level_),
-                     peak_level_ * 0.995f);
-      }
+  if (frame_peak_level == 0) {
+    return peak_level_;

[hlundin-webrtc, 2016/06/30 07:36:23]

I'm all in favor of early returns, but you are no longer running
std::max(peak_level_, 30.f) for this case. I guess it is not needed, but
consider documenting this with RTC_DCHECK_LE(peak_level_, 30.f).

[peah-webrtc, 2016/06/30 14:38:18]

Good point! Added a DCHECK.

Done.

+  }
+
+  if (peak_level_ < frame_peak_level) {
+    // Smoothly update the estimate upwards when the frame peak level is
+    // higher than the estimate.
+    peak_level_ += 0.1f * (frame_peak_level - peak_level_);
+    hold_counter_ = 100;
+    initialization_phase_ = false;
+  } else {
+    hold_counter_ = std::max(0, hold_counter_ - 1);
+
+    // When the signal is highly non-stationary, update the estimate slowly
+    // downwards if the estimate is lower than the frame peak level.
+    if ((signal_type == SignalClassifier::SignalType::kHighlyNonStationary &&
+         hold_counter_ == 0) ||
+        initialization_phase_) {
+      peak_level_ =
+          std::max(peak_level_ + 0.01f * (frame_peak_level - peak_level_),
+                   peak_level_ * 0.995f);
     }
   }