From fe4d67339339066f14d84c2c37661a6d013c9d7c Mon Sep 17 00:00:00 2001
From: Gustaf Ullberg <gustaf@webrtc.org>
Date: Thu, 16 Nov 2017 09:31:27 +0100
Subject: [PATCH] Compute ERL over all frequency bins in AEC3.
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Bug: webrtc:8533
Change-Id: I7160361b3468bb24cef9e6d390f10b23b988edd3
Reviewed-on: https://webrtc-review.googlesource.com/23242
Reviewed-by: Per Åhgren <peah@webrtc.org>
Commit-Queue: Gustaf Ullberg <gustaf@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20713}
---
 .../audio_processing/aec3/erl_estimator.cc    | 23 ++++++++++++++++++-
 modules/audio_processing/aec3/erl_estimator.h |  3 +++
 .../aec3/erl_estimator_unittest.cc            | 12 ++++++----
 3 files changed, 32 insertions(+), 6 deletions(-)

diff --git a/modules/audio_processing/aec3/erl_estimator.cc b/modules/audio_processing/aec3/erl_estimator.cc
index 7923c0da50..3f12ba41a1 100644
--- a/modules/audio_processing/aec3/erl_estimator.cc
+++ b/modules/audio_processing/aec3/erl_estimator.cc
@@ -11,6 +11,7 @@
 #include "modules/audio_processing/aec3/erl_estimator.h"
 
 #include <algorithm>
+#include <numeric>
 
 namespace webrtc {
 
@@ -24,6 +25,8 @@ constexpr float kMaxErl = 1000.f;
 ErlEstimator::ErlEstimator() {
   erl_.fill(kMaxErl);
   hold_counters_.fill(0);
+  erl_time_domain_ = kMaxErl;
+  hold_counter_time_domain_ = 0;
 }
 
 ErlEstimator::~ErlEstimator() = default;
@@ -43,7 +46,7 @@ void ErlEstimator::Update(
       const float new_erl = Y2[k] / X2[k];
       if (new_erl < erl_[k]) {
         hold_counters_[k - 1] = 1000;
-        erl_[k] += 0.1 * (new_erl - erl_[k]);
+        erl_[k] += 0.1f * (new_erl - erl_[k]);
         erl_[k] = std::max(erl_[k], kMinErl);
       }
     }
@@ -58,6 +61,24 @@ void ErlEstimator::Update(
 
   erl_[0] = erl_[1];
   erl_[kFftLengthBy2] = erl_[kFftLengthBy2 - 1];
+
+  // Compute ERL over all frequency bins.
+  const float X2_sum = std::accumulate(X2.begin(), X2.end(), 0.0f);
+
+  if (X2_sum > kX2Min * X2.size()) {
+    const float Y2_sum = std::accumulate(Y2.begin(), Y2.end(), 0.0f);
+    const float new_erl = Y2_sum / X2_sum;
+    if (new_erl < erl_time_domain_) {
+      hold_counter_time_domain_ = 1000;
+      erl_time_domain_ += 0.1f * (new_erl - erl_time_domain_);
+      erl_time_domain_ = std::max(erl_time_domain_, kMinErl);
+    }
+  }
+
+  --hold_counter_time_domain_;
+  erl_time_domain_ = (hold_counter_time_domain_ > 0)
+                         ? erl_time_domain_
+                         : std::min(kMaxErl, 2.f * erl_time_domain_);
 }
 
 }  // namespace webrtc
diff --git a/modules/audio_processing/aec3/erl_estimator.h b/modules/audio_processing/aec3/erl_estimator.h
index 1fe12fb6dd..24b3f4b104 100644
--- a/modules/audio_processing/aec3/erl_estimator.h
+++ b/modules/audio_processing/aec3/erl_estimator.h
@@ -30,10 +30,13 @@ class ErlEstimator {
 
   // Returns the most recent ERL estimate.
   const std::array<float, kFftLengthBy2Plus1>& Erl() const { return erl_; }
+  float ErlTimeDomain() const { return erl_time_domain_; }
 
  private:
   std::array<float, kFftLengthBy2Plus1> erl_;
   std::array<int, kFftLengthBy2Minus1> hold_counters_;
+  float erl_time_domain_;
+  int hold_counter_time_domain_;
 
   RTC_DISALLOW_COPY_AND_ASSIGN(ErlEstimator);
 };
diff --git a/modules/audio_processing/aec3/erl_estimator_unittest.cc b/modules/audio_processing/aec3/erl_estimator_unittest.cc
index 3fbaec0e98..a406581001 100644
--- a/modules/audio_processing/aec3/erl_estimator_unittest.cc
+++ b/modules/audio_processing/aec3/erl_estimator_unittest.cc
@@ -17,9 +17,11 @@ namespace webrtc {
 namespace {
 
 void VerifyErl(const std::array<float, kFftLengthBy2Plus1>& erl,
+               float erl_time_domain,
                float reference) {
   std::for_each(erl.begin(), erl.end(),
                 [reference](float a) { EXPECT_NEAR(reference, a, 0.001); });
+  EXPECT_NEAR(reference, erl_time_domain, 0.001);
 }
 
 }  // namespace
@@ -37,7 +39,7 @@ TEST(ErlEstimator, Estimates) {
   for (size_t k = 0; k < 200; ++k) {
     estimator.Update(X2, Y2);
   }
-  VerifyErl(estimator.Erl(), 10.f);
+  VerifyErl(estimator.Erl(), estimator.ErlTimeDomain(), 10.f);
 
   // Verifies that the ERL is not immediately increased when the ERL in the data
   // increases.
@@ -45,18 +47,18 @@ TEST(ErlEstimator, Estimates) {
   for (size_t k = 0; k < 998; ++k) {
     estimator.Update(X2, Y2);
   }
-  VerifyErl(estimator.Erl(), 10.f);
+  VerifyErl(estimator.Erl(), estimator.ErlTimeDomain(), 10.f);
 
   // Verifies that the rate of increase is 3 dB.
   estimator.Update(X2, Y2);
-  VerifyErl(estimator.Erl(), 20.f);
+  VerifyErl(estimator.Erl(), estimator.ErlTimeDomain(), 20.f);
 
   // Verifies that the maximum ERL is achieved when there are no low RLE
   // estimates.
   for (size_t k = 0; k < 1000; ++k) {
     estimator.Update(X2, Y2);
   }
-  VerifyErl(estimator.Erl(), 1000.f);
+  VerifyErl(estimator.Erl(), estimator.ErlTimeDomain(), 1000.f);
 
   // Verifies that the ERL estimate is is not updated for low-level signals
   X2.fill(1000.f * 1000.f);
@@ -64,7 +66,7 @@ TEST(ErlEstimator, Estimates) {
   for (size_t k = 0; k < 200; ++k) {
     estimator.Update(X2, Y2);
   }
-  VerifyErl(estimator.Erl(), 1000.f);
+  VerifyErl(estimator.Erl(), estimator.ErlTimeDomain(), 1000.f);
 }
 
 }  // namespace webrtc