Robustification of the AEC3 echo removal in the first part of the call

webrtc/modules/audio_processing/aec3/residual_echo_estimator.cc

Index: webrtc/modules/audio_processing/aec3/residual_echo_estimator.cc
diff --git a/webrtc/modules/audio_processing/aec3/residual_echo_estimator.cc b/webrtc/modules/audio_processing/aec3/residual_echo_estimator.cc
index d17afa6906d2e49ee74ca721168d7b869f64e04f..61208118c7aeacb586e00711cab6b36f82dccead 100644
--- a/webrtc/modules/audio_processing/aec3/residual_echo_estimator.cc
+++ b/webrtc/modules/audio_processing/aec3/residual_echo_estimator.cc
@@ -136,9 +136,7 @@ void ResidualEchoEstimator::Estimate(
         X2.begin(), X2.end(), X2_noise_floor_.begin(), X2.begin(),
         [](float a, float b) { return std::max(0.f, a - 10.f * b); });
 
-    NonLinearEstimate(
-        aec_state.HeadsetDetected() ? kHeadsetEchoPathGain : kFixedEchoPathGain,
-        X2, Y2, R2);
+    NonLinearEstimate(aec_state.HeadsetDetected(), X2, Y2, R2);
     AddEchoReverb(*R2, aec_state.SaturatedEcho(),
                   std::min(static_cast<size_t>(kAdaptiveFilterLength),
                            delay.value_or(kAdaptiveFilterLength)),
@@ -184,13 +182,27 @@ void ResidualEchoEstimator::LinearEstimate(
 }
 
 void ResidualEchoEstimator::NonLinearEstimate(
-    float echo_path_gain,
+    bool headset_detected,
     const std::array<float, kFftLengthBy2Plus1>& X2,
     const std::array<float, kFftLengthBy2Plus1>& Y2,
     std::array<float, kFftLengthBy2Plus1>* R2) {
+  // Choose gains.
+  const float echo_path_gain_lf = headset_detected ? kHeadsetEchoPathGain : 100;
+  const float echo_path_gain_mf =
+      headset_detected ? kHeadsetEchoPathGain : 1000;
+  const float echo_path_gain_hf =
+      headset_detected ? kHeadsetEchoPathGain : 5000;
+
   // Compute preliminary residual echo.
-  std::transform(X2.begin(), X2.end(), R2->begin(),
-                 [echo_path_gain](float a) { return a * echo_path_gain; });
+  std::transform(
+      X2.begin(), X2.begin() + 12, R2->begin(),
+      [echo_path_gain_lf](float a) { return a * echo_path_gain_lf; });
+  std::transform(
+      X2.begin() + 12, X2.begin() + 25, R2->begin() + 12,
+      [echo_path_gain_mf](float a) { return a * echo_path_gain_mf; });
+  std::transform(
+      X2.begin() + 25, X2.end(), R2->begin() + 25,
+      [echo_path_gain_hf](float a) { return a * echo_path_gain_hf; });
 
   for (size_t k = 0; k < R2->size(); ++k) {
     // Update hold counter.