From 5bb98971ce890be83add3282c7c421ff4f613599 Mon Sep 17 00:00:00 2001
From: Gustaf Ullberg <gustaf@webrtc.org>
Date: Wed, 25 Apr 2018 12:54:59 +0200
Subject: [PATCH] Remove attenuation of narrow banded peaks
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The code that attenuates narrow banded echo peaks in low frequencies
is removed as it affects transparency negatively.

Bug: webrtc:9192,chromium:836729
Change-Id: Ib90ce6a3db0a75e8d69bdca432e1f8f8bfbbd988
Reviewed-on: https://webrtc-review.googlesource.com/72380
Reviewed-by: Per Åhgren <peah@webrtc.org>
Commit-Queue: Gustaf Ullberg <gustaf@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23022}
---
 .../audio_processing/aec3/suppression_gain.cc | 23 ++-----------------
 .../audio_processing/aec3/suppression_gain.h  |  1 -
 2 files changed, 2 insertions(+), 22 deletions(-)

diff --git a/modules/audio_processing/aec3/suppression_gain.cc b/modules/audio_processing/aec3/suppression_gain.cc
index 110c23279d..fbd2e405d9 100644
--- a/modules/audio_processing/aec3/suppression_gain.cc
+++ b/modules/audio_processing/aec3/suppression_gain.cc
@@ -26,21 +26,6 @@
 namespace webrtc {
 namespace {
 
-// Reduce gain to avoid narrow band echo leakage.
-void NarrowBandAttenuation(int narrow_bin,
-                           const std::array<float, kFftLengthBy2Plus1>& nearend,
-                           const std::array<float, kFftLengthBy2Plus1>& echo,
-                           std::array<float, kFftLengthBy2Plus1>* gain) {
-  // TODO(peah): Verify that the condition below is not too conservative.
-  if (10.f * echo[narrow_bin] > nearend[narrow_bin]) {
-    const int upper_bin =
-        std::min(narrow_bin + 6, static_cast<int>(kFftLengthBy2Plus1 - 1));
-    for (int k = std::max(0, narrow_bin - 6); k <= upper_bin; ++k) {
-      (*gain)[k] = std::min((*gain)[k], 0.001f);
-    }
-  }
-}
-
 // Adjust the gains according to the presence of known external filters.
 void AdjustForExternalFilters(std::array<float, kFftLengthBy2Plus1>* gain) {
   // Limit the low frequency gains to avoid the impact of the high-pass filter
@@ -271,7 +256,6 @@ void AdjustNonConvergedFrequencies(
 // TODO(peah): Add further optimizations, in particular for the divisions.
 void SuppressionGain::LowerBandGain(
     bool low_noise_render,
-    const rtc::Optional<int>& narrow_peak_band,
     const AecState& aec_state,
     const std::array<float, kFftLengthBy2Plus1>& nearend,
     const std::array<float, kFftLengthBy2Plus1>& echo,
@@ -321,9 +305,6 @@ void SuppressionGain::LowerBandGain(
                         linear_echo_estimate, nearend, weighted_echo, masker,
                         min_gain, max_gain, one_by_weighted_echo, gain);
     AdjustForExternalFilters(gain);
-    if (narrow_peak_band) {
-      NarrowBandAttenuation(*narrow_peak_band, nearend, weighted_echo, gain);
-    }
   }
 
   // Adjust the gain for frequencies which have not yet converged.
@@ -379,8 +360,8 @@ void SuppressionGain::GetGain(
   bool low_noise_render = low_render_detector_.Detect(render);
   const rtc::Optional<int> narrow_peak_band =
       render_signal_analyzer.NarrowPeakBand();
-  LowerBandGain(low_noise_render, narrow_peak_band, aec_state, nearend_spectrum,
-                echo_spectrum, comfort_noise_spectrum, low_band_gain);
+  LowerBandGain(low_noise_render, aec_state, nearend_spectrum, echo_spectrum,
+                comfort_noise_spectrum, low_band_gain);
 
   const float gain_upper_bound = aec_state.SuppressionGainLimit();
   if (gain_upper_bound < 1.f) {
diff --git a/modules/audio_processing/aec3/suppression_gain.h b/modules/audio_processing/aec3/suppression_gain.h
index 59eeb35857..23121a2324 100644
--- a/modules/audio_processing/aec3/suppression_gain.h
+++ b/modules/audio_processing/aec3/suppression_gain.h
@@ -47,7 +47,6 @@ class SuppressionGain {
 
  private:
   void LowerBandGain(bool stationary_with_low_power,
-                     const rtc::Optional<int>& narrow_peak_band,
                      const AecState& aec_state,
                      const std::array<float, kFftLengthBy2Plus1>& nearend,
                      const std::array<float, kFftLengthBy2Plus1>& echo,