AEC3: Introduce partial adaptive filter resets at echo path changes

With this CL, the main and shadow filters are no longer fully reset to
0 as the delay changes. This allows for more robust echo removal for
some scenarios.

Bug: webrtc:9879,chromium:895838
Change-Id: I859aa3df3ae41648bc8efde01ec2e2a5cb392279
Reviewed-on: https://webrtc-review.googlesource.com/c/106345
Reviewed-by: Gustaf Ullberg <gustaf@webrtc.org>
Commit-Queue: Per Åhgren <peah@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#25251}

modules/audio_processing/aec3/adaptive_fir_filter.cc

@@ -25,6 +25,7 @@
 #include "modules/audio_processing/aec3/fft_data.h"
 #include "rtc_base/checks.h"
 #include "rtc_base/logging.h"
+#include "system_wrappers/include/field_trial.h"
 
 namespace webrtc {
 
@@ -417,12 +418,21 @@ void ApplyFilter_SSE2(const RenderBuffer& render_buffer,
 
 }  // namespace aec3
 
+namespace {
+
+bool EnablePartialFilterReset() {
+  return !field_trial::IsEnabled("WebRTC-Aec3PartialFilterResetKillSwitch");
+}
+
+}  // namespace
+
 AdaptiveFirFilter::AdaptiveFirFilter(size_t max_size_partitions,
                                      size_t initial_size_partitions,
                                      size_t size_change_duration_blocks,
                                      Aec3Optimization optimization,
                                      ApmDataDumper* data_dumper)
     : data_dumper_(data_dumper),
+      use_partial_filter_reset_(EnablePartialFilterReset()),
       fft_(),
       optimization_(optimization),
       max_size_partitions_(max_size_partitions),
@@ -455,20 +465,22 @@ AdaptiveFirFilter::~AdaptiveFirFilter() = default;
 void AdaptiveFirFilter::HandleEchoPathChange() {
   size_t current_h_size = h_.size();
   h_.resize(GetTimeDomainLength(max_size_partitions_));
-  std::fill(h_.begin(), h_.end(), 0.f);
+  const size_t begin_coeffficient =
+      use_partial_filter_reset_ ? current_h_size : 0;
+  std::fill(h_.begin() + begin_coeffficient, h_.end(), 0.f);
   h_.resize(current_h_size);
 
   size_t current_size_partitions = H_.size();
   H_.resize(max_size_partitions_);
-  for (auto& H_j : H_) {
+  H2_.resize(max_size_partitions_);
-    H_j.Clear();
+
+  const size_t begin_partition =
+      use_partial_filter_reset_ ? current_size_partitions : 0;
+  for (size_t k = begin_partition; k < max_size_partitions_; ++k) {
+    H_[k].Clear();
+    H2_[k].fill(0.f);
   }
   H_.resize(current_size_partitions);
-
-  H2_.resize(max_size_partitions_);
-  for (auto& H2_k : H2_) {
-    H2_k.fill(0.f);
-  }
   H2_.resize(current_size_partitions);
 
   erl_.fill(0.f);

modules/audio_processing/aec3/adaptive_fir_filter.h

@@ -164,6 +164,7 @@ class AdaptiveFirFilter {
   void UpdateSize();
 
   ApmDataDumper* const data_dumper_;
+  const bool use_partial_filter_reset_;
   const Aec3Fft fft_;
   const Aec3Optimization optimization_;
   const size_t max_size_partitions_;

modules/audio_processing/aec3/subtractor_unittest.cc

@@ -210,21 +210,4 @@ TEST(Subtractor, NonConvergenceOnUncorrelatedSignals) {
   }
 }
 
-// Verifies that the subtractor is properly reset when there is an echo path
-// change.
-TEST(Subtractor, EchoPathChangeReset) {
-  std::vector<int> blocks_with_echo_path_changes;
-  blocks_with_echo_path_changes.push_back(99);
-  for (size_t filter_length_blocks : {12, 20, 30}) {
-    for (size_t delay_samples : {0, 64, 150, 200, 301}) {
-      SCOPED_TRACE(ProduceDebugText(delay_samples, filter_length_blocks));
-
-      float echo_to_nearend_power = RunSubtractorTest(
-          100, delay_samples, filter_length_blocks, filter_length_blocks, false,
-          blocks_with_echo_path_changes);
-      EXPECT_NEAR(1.f, echo_to_nearend_power, 0.0000001f);
-    }
-  }
-}
-
 }  // namespace webrtc