Finalization of the first version of EchoCanceller 3

webrtc/modules/audio_processing/aec3/aec_state.cc

Index: webrtc/modules/audio_processing/aec3/aec_state.cc
diff --git a/webrtc/modules/audio_processing/aec3/aec_state.cc b/webrtc/modules/audio_processing/aec3/aec_state.cc
new file mode 100644
index 0000000000000000000000000000000000000000..4d75baf7759fe45f76b8783cc9ba29a478af2231
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+++ b/webrtc/modules/audio_processing/aec3/aec_state.cc
@@ -0,0 +1,160 @@
+/*
+ *  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/atomicops.h"
+#include "webrtc/base/checks.h"
+#include "webrtc/modules/audio_processing/logging/apm_data_dumper.h"
+
+namespace webrtc {
+namespace {
+
+constexpr float kMaxFilterEstimateStrength = 1000.f;
+
+// Compute the delay of the adaptive filter as the partition with a distinct
+// peak.
+void AnalyzeFilter(
+    const std::vector<std::array<float, kFftLengthBy2Plus1>>&
+        filter_frequency_response,
+    std::array<bool, kFftLengthBy2Plus1>* bands_with_reliable_filter,
+    std::array<float, kFftLengthBy2Plus1>* filter_estimate_strength,
+    rtc::Optional<size_t>* filter_delay) {
+  const auto& H2 = filter_frequency_response;
+
+  size_t reliable_delays_sum = 0;
+  size_t num_reliable_delays = 0;
+
+  constexpr size_t kUpperBin = kFftLengthBy2 - 5;
+  for (size_t k = 1; k < kUpperBin; ++k) {
+    int peak = 0;
+    for (size_t j = 0; j < H2.size(); ++j) {
+      if (H2[j][k] > H2[peak][k]) {
+        peak = j;
+      }
+    }
+
+    if (H2[peak][k] == 0.f) {
+      (*filter_estimate_strength)[k] = 0.f;
+    } else if (H2[H2.size() - 1][k] == 0.f) {
+      (*filter_estimate_strength)[k] = kMaxFilterEstimateStrength;
+    } else {
+      (*filter_estimate_strength)[k] = std::min(
+          kMaxFilterEstimateStrength, H2[peak][k] / H2[H2.size() - 1][k]);
+    }
+
+    constexpr float kMargin = 10.f;
+    if (kMargin * H2[H2.size() - 1][k] < H2[peak][k]) {
+      (*bands_with_reliable_filter)[k] = true;
+      reliable_delays_sum += peak;
+      ++num_reliable_delays;
+    } else {
+      (*bands_with_reliable_filter)[k] = false;
+    }
+  }
+  (*bands_with_reliable_filter)[0] = (*bands_with_reliable_filter)[1];
+  std::fill(bands_with_reliable_filter->begin() + kUpperBin,
+            bands_with_reliable_filter->end(),
+            (*bands_with_reliable_filter)[kUpperBin - 1]);
+  (*filter_estimate_strength)[0] = (*filter_estimate_strength)[1];
+  std::fill(filter_estimate_strength->begin() + kUpperBin,
+            filter_estimate_strength->end(),
+            (*filter_estimate_strength)[kUpperBin - 1]);
+
+  *filter_delay =
+      num_reliable_delays > 20
+          ? rtc::Optional<size_t>(reliable_delays_sum / num_reliable_delays)
+          : rtc::Optional<size_t>();
+}
+
+constexpr int kActiveRenderCounterInitial = 50;
+constexpr int kActiveRenderCounterMax = 200;
+constexpr int kEchoPathChangeCounterInitial = 50;
+constexpr int kEchoPathChangeCounterMax = 200;
+
+}  // namespace
+
+int AecState::instance_count_ = 0;
+
+AecState::AecState()
+    : data_dumper_(
+          new ApmDataDumper(rtc::AtomicOps::Increment(&instance_count_))),
+      echo_path_change_counter_(kEchoPathChangeCounterInitial),
+      active_render_counter_(kActiveRenderCounterInitial) {
+  bands_with_reliable_filter_.fill(false);
+  filter_estimate_strength_.fill(0.f);
+}
+
+AecState::~AecState() = default;
+
+void AecState::Update(const std::vector<std::array<float, kFftLengthBy2Plus1>>&
+                          filter_frequency_response,
+                      const rtc::Optional<size_t>& external_delay_samples,
+                      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 EchoPathVariability& echo_path_variability,
+                      bool echo_leakage_detected) {
+  filter_length_ = filter_frequency_response.size();
+  AnalyzeFilter(filter_frequency_response, &bands_with_reliable_filter_,
+                &filter_estimate_strength_, &filter_delay_);
+  // Compute the externally provided delay in partitions. The truncation is
+  // intended here.
+  external_delay_ =
+      external_delay_samples
+          ? rtc::Optional<size_t>(*external_delay_samples / kBlockSize)
+          : rtc::Optional<size_t>();
+
+  const float x_energy =
+      std::accumulate(x.begin(), x.end(), 0.f,

[hlundin-webrtc, 2017/02/22 15:24:06]

Optional: Could also use inner_product, I suppose.

[peah-webrtc, 2017/02/22 23:51:37]

I changed to that as it makes the code more compact. I'm concerned it could be
slower, as inner_product uses 2 iterators. But I think compactness is more
important in this case, since very likely we should anyway replace this by
SSE2/NEON versions.

Done.

+                      [](float a, float b) -> float { return a + b * b; });
+  echo_path_change_counter_ = echo_path_variability.AudioPathChanged()
+                                  ? kEchoPathChangeCounterMax
+                                  : echo_path_change_counter_ - 1;

[hlundin-webrtc, 2017/02/22 15:24:06]

What happens when echo_path_change_counter_ goes negative? Is that intentional?

[peah-webrtc, 2017/02/22 23:51:37]

Yes, that is intentional, as allowing it to go below 0 avoids the need to check
to avoid that. This is reflected in the check below.

[hlundin-webrtc, 2017/02/23 07:42:09]

Acknowledged.

[peah-webrtc, 2017/02/23 11:18:32]

Acknowledged.

+  active_render_counter_ = x_energy > 10000 * kFftLengthBy2
+                               ? kActiveRenderCounterMax
+                               : active_render_counter_ - 1;

[hlundin-webrtc, 2017/02/22 15:24:06]

Same here.

[peah-webrtc, 2017/02/22 23:51:36]

That is intended as well. The check is for when it is above 0. We should,
however, probably harmonize the way counters are used within AEC3 in a followup
cleanup CL.

+
+  usable_linear_estimate_ = filter_delay_ && echo_path_change_counter_ <= 0;
+
+  echo_leakage_detected_ = echo_leakage_detected;
+
+  model_based_aec_feasible_ = usable_linear_estimate_ || external_delay_;
+
+  if (usable_linear_estimate_) {
+    const std::array<float, kFftLengthBy2Plus1>& X2 =

[hlundin-webrtc, 2017/02/22 15:24:05]

const auto&

[peah-webrtc, 2017/02/22 23:51:36]

Done.

+        X_buffer.Spectrum(*filter_delay_);
+
+    // TODO(peah): Expose these as stats.
+    erle_estimator_.Update(X2, Y2, E2_main);
+    erl_estimator_.Update(X2, Y2);
+
+    // TODO(peah): Add working functionality for headset detection.
+    const auto& erl = erl_estimator_.Erl();
+    const int low_erl_band_count = std::count_if(
+        erl.begin(), erl.end(), [](float a) { return a <= 0.1f; });
+
+    const int noisy_band_count = std::count_if(
+        filter_estimate_strength_.begin(), filter_estimate_strength_.end(),
+        [](float a) { return a <= 10.f; });
+    headset_detected_ = low_erl_band_count > 20 && noisy_band_count > 20;
+    headset_detected_ = false;

[hlundin-webrtc, 2017/02/22 15:24:06]

Is this short-circuit because the above detection does not work? If so, please
comment that explicitly.

[peah-webrtc, 2017/02/22 23:51:37]

That is correct, or rather, it does not work yet. I instead #ifdef that code
away for now.

Done.

[hlundin-webrtc, 2017/02/23 07:42:09]

Acknowledged.

[peah-webrtc, 2017/02/23 11:18:32]

Acknowledged.

+  } else {
+    headset_detected_ = false;
+  }
+}
+
+}  // namespace webrtc