Major updates to the echo removal functionality in AEC3

webrtc/modules/audio_processing/aec3/output_selector.cc

 /*
  *  Copyright (c) 2017 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.
  */
 
@@ skipping 16 matching lines @@
 
   const float change_factor = (from_y_to_e ? 1.f : -1.f) / e.size();
   float averaging = from_y_to_e ? 0.f : 1.f;
   for (size_t k = 0; k < e.size(); ++k) {
     y[k] += averaging * (e[k] - y[k]);
     averaging += change_factor;
   }
   RTC_DCHECK_EQ(from_y_to_e ? 1.f : 0.f, averaging);
 }
 
-float BlockPower(rtc::ArrayView<const float> x) {
-  return std::accumulate(x.begin(), x.end(), 0.f,
-                         [](float a, float b) -> float { return a + b * b; });
-}
-
 }  // namespace
 
 OutputSelector::OutputSelector() = default;
 
 OutputSelector::~OutputSelector() = default;
 
 void OutputSelector::FormLinearOutput(
+    bool use_subtractor_output,
     rtc::ArrayView<const float> subtractor_output,
     rtc::ArrayView<float> capture) {
   RTC_DCHECK_EQ(subtractor_output.size(), capture.size());
   rtc::ArrayView<const float>& e_main = subtractor_output;
   rtc::ArrayView<float> y = capture;
 
-  const bool subtractor_output_is_best =
-      BlockPower(y) > 1.5f * BlockPower(e_main);
-  output_change_counter_ = subtractor_output_is_best != use_subtractor_output_
-                               ? output_change_counter_ + 1
-                               : 0;
-
-  if (subtractor_output_is_best != use_subtractor_output_ &&
-      ((subtractor_output_is_best && output_change_counter_ > 3) ||
-       (!subtractor_output_is_best && output_change_counter_ > 10))) {
-    use_subtractor_output_ = subtractor_output_is_best;
+  if (use_subtractor_output != use_subtractor_output_) {
+    use_subtractor_output_ = use_subtractor_output;
     SmoothFrameTransition(use_subtractor_output_, e_main, y);
-    output_change_counter_ = 0;
   } else if (use_subtractor_output_) {
     std::copy(e_main.begin(), e_main.end(), y.begin());
   }
 }
 
 }  // namespace webrtc