Finalization of the first version of EchoCanceller 3

webrtc/modules/audio_processing/aec3/shadow_filter_update_gain.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/shadow_filter_update_gain.h"
+
+#include <algorithm>
+#include <functional>
+
+#include "webrtc/base/checks.h"
+
+namespace webrtc {
+
+void ShadowFilterUpdateGain::Compute(
+    const FftBuffer& X_buffer,
+    const RenderSignalAnalyzer& render_signal_analyzer,
+    const FftData& E_shadow,
+    size_t size_partitions,
+    bool saturated_capture_signal,
+    FftData* G) {
+  RTC_DCHECK(G);
+  ++call_counter_;
+
+  if (render_signal_analyzer.PoorSignalExcitation()) {
+    poor_signal_excitation_counter_ = 0;
+  }
+
+  // Do not update the filter if the render is not sufficiently excited.
+  if (++poor_signal_excitation_counter_ < size_partitions ||
+      saturated_capture_signal || call_counter_ <= size_partitions) {
+    G->re.fill(0.f);
+    G->im.fill(0.f);
+    return;
+  }
+
+  // Compute mu.
+  constexpr float kX2Min = 44015068.0f;
+  constexpr float kMuFixed = .5f;
+  std::array<float, kFftLengthBy2Plus1> mu;
+  const auto& X2 = X_buffer.SpectralSum(size_partitions);
+  std::transform(X2.begin(), X2.end(), mu.begin(),
+                 [&](float a) { return a > kX2Min ? kMuFixed / a : 0.f; });
+
+  // Avoid updating the filter close to narrow bands in the render signals.
+  render_signal_analyzer.MaskRegionsAroundNarrowBands(&mu);
+
+  // G = mu * E * X2.
+  std::transform(mu.begin(), mu.end(), E_shadow.re.begin(), G->re.begin(),
+                 std::multiplies<float>());
+  std::transform(mu.begin(), mu.end(), E_shadow.im.begin(), G->im.begin(),
+                 std::multiplies<float>());
+}
+
+}  // namespace webrtc