Major updates to the echo removal functionality in AEC3

webrtc/modules/audio_processing/aec3/power_echo_model.cc

Index: webrtc/modules/audio_processing/aec3/power_echo_model.cc
diff --git a/webrtc/modules/audio_processing/aec3/power_echo_model.cc b/webrtc/modules/audio_processing/aec3/power_echo_model.cc
deleted file mode 100644
index dee03d8d09b1f872b55d0906e9aa02eef9714ab2..0000000000000000000000000000000000000000
--- a/webrtc/modules/audio_processing/aec3/power_echo_model.cc
+++ /dev/null
@@ -1,111 +0,0 @@
-/*
- *  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.
- */
-#include "webrtc/modules/audio_processing/aec3/power_echo_model.h"
-
-#include <string.h>
-#include <algorithm>
-
-#include "webrtc/base/optional.h"
-
-namespace webrtc {
-namespace {
-
-// Computes the spectral power over that last 20 frames.
-void RecentMaximum(const RenderBuffer& X_buffer,
-                   std::array<float, kFftLengthBy2Plus1>* R2) {
-  R2->fill(0.f);
-  for (size_t j = 0; j < 20; ++j) {
-    std::transform(R2->begin(), R2->end(), X_buffer.Spectrum(j).begin(),
-                   R2->begin(),
-                   [](float a, float b) { return std::max(a, b); });
-  }
-}
-
-constexpr float kHInitial = 10.f;
-constexpr int kUpdateCounterInitial = 300;
-
-}  // namespace
-
-PowerEchoModel::PowerEchoModel() {
-  H2_.fill(CountedFloat(kHInitial, kUpdateCounterInitial));
-}
-
-PowerEchoModel::~PowerEchoModel() = default;
-
-void PowerEchoModel::HandleEchoPathChange(
-    const EchoPathVariability& variability) {
-  if (variability.gain_change) {
-    H2_.fill(CountedFloat(kHInitial, kUpdateCounterInitial));
-  }
-}
-
-void PowerEchoModel::EstimateEcho(
-    const RenderBuffer& render_buffer,
-    const std::array<float, kFftLengthBy2Plus1>& capture_spectrum,
-    const AecState& aec_state,
-    std::array<float, kFftLengthBy2Plus1>* echo_spectrum) {
-  RTC_DCHECK(echo_spectrum);
-
-  const RenderBuffer& X_buffer = render_buffer;
-  const auto& Y2 = capture_spectrum;
-  std::array<float, kFftLengthBy2Plus1>* S2 = echo_spectrum;
-
-  // Choose delay to use.
-  const rtc::Optional<size_t> delay =
-      aec_state.FilterDelay()
-          ? aec_state.FilterDelay()
-          : (aec_state.ExternalDelay() ? rtc::Optional<size_t>(std::min<size_t>(
-                                             *aec_state.ExternalDelay(),
-                                             X_buffer.Buffer().size() - 1))
-                                       : rtc::Optional<size_t>());
-
-  // Compute R2.
-  std::array<float, kFftLengthBy2Plus1> render_max;
-  if (!delay) {
-    RecentMaximum(render_buffer, &render_max);
-  }
-  const std::array<float, kFftLengthBy2Plus1>& X2_active =
-      delay ? render_buffer.Spectrum(*delay) : render_max;
-
-  if (!aec_state.SaturatedCapture()) {
-    // Corresponds of WGN of power -46dBFS.
-    constexpr float kX2Min = 44015068.0f;
-    const int max_update_counter_value = delay ? 300 : 500;
-
-    std::array<float, kFftLengthBy2Plus1> new_H2;
-
-    // new_H2 = Y2 / X2.
-    std::transform(X2_active.begin(), X2_active.end(), Y2.begin(),
-                   new_H2.begin(),
-                   [&](float a, float b) { return a > kX2Min ? b / a : -1.f; });
-
-    // Lambda for updating H2 in a maximum statistics manner.
-    auto H2_updater = [&](float a, CountedFloat b) {
-      if (a > 0) {
-        if (a > b.value) {
-          b.counter = max_update_counter_value;
-          b.value = a;
-        } else if (--b.counter <= 0) {
-          b.value = std::max(b.value * 0.9f, 1.f);
-        }
-      }
-      return b;
-    };
-
-    std::transform(new_H2.begin(), new_H2.end(), H2_.begin(), H2_.begin(),
-                   H2_updater);
-  }
-
-  // S2 = H2*X2_active.
-  std::transform(H2_.begin(), H2_.end(), X2_active.begin(), S2->begin(),
-                 [](CountedFloat a, float b) { return a.value * b; });
-}
-
-}  // namespace webrtc