Finalization of the first version of EchoCanceller 3

webrtc/modules/audio_processing/aec3/aec_state.cc

+/*
+ *  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/aec_state.h"
+
+#include <math.h>
+#include <numeric>
+#include <vector>
+
+#include "webrtc/base/checks.h"
+
+namespace webrtc {
+namespace {
+
+// Updates the bands where the filter performs reliable.
+void UpdateBandsWithReliableFilter(
+    rtc::ArrayView<const float> E2_main,
+    rtc::ArrayView<const float> E2_shadow,
+    rtc::ArrayView<const float> X2,
+    rtc::ArrayView<const float> Y2,
+    rtc::ArrayView<bool> bands_with_reliable_filter) {
+  const float kX2Min = 44015068.0f / 1000.f;

[ivoc, 2017/02/10 13:52:33]

A comment about where this value comes from would be helpful.

[peah-webrtc, 2017/02/20 07:37:15]

Good point! It has now been removed though.

Done.

[ivoc, 2017/02/21 17:26:00]

Acknowledged.

[peah-webrtc, 2017/02/21 23:00:39]

Acknowledged.

+  for (size_t k = 1; k < kFftLengthBy2 - 5; ++k) {
+    if (X2[k] > kX2Min) {
+      if (E2_main[k] > Y2[k]) {
+        bands_with_reliable_filter[k] = false;
+      } else {

[ivoc, 2017/02/10 13:52:33]

this can be "else if" to avoid the nested if. One thing that worries me a bit in
this loop is the possibility for elements in |bands_with_reliable_filter| to not
be changed. if the "if" and the "else if" don't hold, the old value will remain.
Is that the intended behavior?

[peah-webrtc, 2017/02/20 07:37:15]

You definitely have a point. And in the tuning, this did not perform how I
wanted. Therefore I have removed it.

Done.

[ivoc, 2017/02/21 17:26:00]

Acknowledged.

[peah-webrtc, 2017/02/21 23:00:39]

Acknowledged.

+        if ((2 * E2_main[k] < Y2[k]) || (E2_shadow[k] < E2_main[k])) {
+          bands_with_reliable_filter[k] = true;
+        }
+      }
+    }
+  }
+
+  bands_with_reliable_filter[0] = bands_with_reliable_filter[1];
+  std::fill(bands_with_reliable_filter.begin() + kFftLengthBy2 - 5,
+            bands_with_reliable_filter.end(),
+            bands_with_reliable_filter[kFftLengthBy2 - 6]);
+}
+
+constexpr int kActiveRenderCounterInitial = 50;
+constexpr int kActiveRenderCounterMax = 200;
+constexpr int kEchoPathChangeCounterInitial = 50;
+constexpr int kEchoPathChangeCounterMax = 200;
+
+}  // namespace
+
+AecState::AecState()
+    : echo_path_change_counter_(kEchoPathChangeCounterInitial),
+      active_render_counter_(kActiveRenderCounterInitial) {
+  bands_with_reliable_filter_.fill(false);
+}
+
+AecState::~AecState() = default;
+
+void AecState::Update(const FftBuffer& X_buffer,
+                      const std::array<float, kFftLengthBy2Plus1>& E2_main,
+                      const std::array<float, kFftLengthBy2Plus1>& E2_shadow,
+                      const std::array<float, kFftLengthBy2Plus1>& Y2,
+                      rtc::ArrayView<const float> x,
+                      const DelayHandler& delay_handler,
+                      const EchoPathVariability& echo_path_variability,
+                      bool echo_leakage_detected) {
+  const rtc::Optional<size_t> linear_filter_based_delay =
+      delay_handler.FilterDelay();
+
+  const float x_energy =
+      std::accumulate(x.begin(), x.end(), 0.f,
+                      [](float a, float b) -> float { return a + b * b; });
+  echo_path_change_counter_ = echo_path_variability.AudioPathChanged()
+                                  ? kEchoPathChangeCounterMax
+                                  : echo_path_change_counter_ - 1;
+  active_render_counter_ = x_energy > 10000 * kFftLengthBy2
+                               ? kActiveRenderCounterMax
+                               : active_render_counter_ - 1;
+
+  usable_linear_estimate_ =
+      linear_filter_based_delay && echo_path_change_counter_ <= 0;
+
+  echo_leakage_detected_ = echo_leakage_detected;
+
+  model_based_aec_feasible_ =
+      usable_linear_estimate_ ||
+      (delay_handler.ExternalDelay() && echo_path_change_counter_ <= 0);
+
+  if (usable_linear_estimate_) {
+    const std::array<float, kFftLengthBy2Plus1>& X2 =
+        X_buffer.Spectrum(*linear_filter_based_delay);
+
+    UpdateBandsWithReliableFilter(E2_main, E2_shadow, X2, Y2,
+                                  bands_with_reliable_filter_);
+
+    // TODO(peah): Expose these as stats.
+    erle_estimator_.Update(X2, Y2, E2_main);
+    erl_estimator_.Update(X2, Y2);
+  }
+}
+
+}  // namespace webrtc