commit 9ad845d2ab5cbc146c4afbe9cf7158a2bb710626
author Per Åhgren <peah@webrtc.org> Sun May 06 19:17:20 2018
committer Commit Bot <commit-bot@chromium.org> Mon May 07 13:52:08 2018
tree 92cfaa391d9e57375a176a4d0057ffae0d8fe74e
parent 623d28179239fa5f31fdf6c706cc5de6bcc5f3a7

Soften the AEC3 transparent mode to handle broken headsets

This CL softens the effect of the AEC3 transparent mode to also handle
headsets that leak low-level echoes in a nonlinear way.
This is handled by reintroducing the limit in the echo path gain for the
nonlinear mode. Due to recent improvements in echo suppressor behavior
this is now possible to do with a limited impact on the near-end speech.

Bug: webrtc:9246,chromium:840347
Change-Id: I0ca5157160d1884ba93b962323b56016756986d3
Reviewed-on: https://webrtc-review.googlesource.com/74703
Reviewed-by: Gustaf Ullberg <gustaf@webrtc.org>
Commit-Queue: Per Åhgren <peah@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23145}

modules/audio_processing/aec3/residual_echo_estimator.cc

diff --git a/modules/audio_processing/aec3/residual_echo_estimator.cc b/modules/audio_processing/aec3/residual_echo_estimator.cc
index 31ad319..19f65d0 100644
--- a/modules/audio_processing/aec3/residual_echo_estimator.cc
+++ b/modules/audio_processing/aec3/residual_echo_estimator.cc
@@ -15,11 +15,21 @@
 #include <vector>
 
 #include "rtc_base/checks.h"
+#include "system_wrappers/include/field_trial.h"
 
 namespace webrtc {
+namespace {
+
+bool EnableSoftTransparentMode() {
+  return !field_trial::IsEnabled("WebRTC-Aec3SoftTransparentModeKillSwitch");
+}
+
+}  // namespace
 
 ResidualEchoEstimator::ResidualEchoEstimator(const EchoCanceller3Config& config)
-    : config_(config), S2_old_(config_.filter.main.length_blocks) {
+    : config_(config),
+      S2_old_(config_.filter.main.length_blocks),
+      soft_transparent_mode_(EnableSoftTransparentMode()) {
   Reset();
 }
 
@@ -64,7 +74,10 @@
                          0.f, a - config_.echo_model.stationary_gate_slope * b);
                    });
 
-    NonLinearEstimate(aec_state.EchoPathGain(), X2, Y2, R2);
+    float echo_path_gain = aec_state.TransparentMode() && soft_transparent_mode_
+                               ? 0.01f
+                               : aec_state.EchoPathGain();
+    NonLinearEstimate(echo_path_gain, X2, Y2, R2);
 
     // If the echo is saturated, estimate the echo power as the maximum echo
     // power with a leakage factor.
@@ -87,12 +100,13 @@
       }
     }
   }
-
-  // If the echo is deemed inaudible, set the residual echo to zero.
-  if (aec_state.TransparentMode()) {
-    R2->fill(0.f);
-    R2_old_.fill(0.f);
-    R2_hold_counter_.fill(0.f);
+  if (!soft_transparent_mode_) {
+    // If the echo is deemed inaudible, set the residual echo to zero.
+    if (aec_state.TransparentMode()) {
+      R2->fill(0.f);
+      R2_old_.fill(0.f);
+      R2_hold_counter_.fill(0.f);
+    }
   }
 
   std::copy(R2->begin(), R2->end(), R2_old_.begin());

modules/audio_processing/aec3/residual_echo_estimator.h

diff --git a/modules/audio_processing/aec3/residual_echo_estimator.h b/modules/audio_processing/aec3/residual_echo_estimator.h
index b789c0c..d03b89a 100644
--- a/modules/audio_processing/aec3/residual_echo_estimator.h
+++ b/modules/audio_processing/aec3/residual_echo_estimator.h
@@ -82,6 +82,7 @@
   std::vector<std::array<float, kFftLengthBy2Plus1>> S2_old_;
   std::array<float, kFftLengthBy2Plus1> X2_noise_floor_;
   std::array<int, kFftLengthBy2Plus1> X2_noise_floor_counter_;
+  const bool soft_transparent_mode_;
 
   RTC_DISALLOW_IMPLICIT_CONSTRUCTORS(ResidualEchoEstimator);
 };