Transparency improvements in the echo canceller 3

webrtc/modules/audio_processing/aec3/subtractor.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/subtractor.h"
 
 #include <algorithm>
 
 #include "webrtc/modules/audio_processing/logging/apm_data_dumper.h"
 #include "webrtc/rtc_base/array_view.h"
 #include "webrtc/rtc_base/checks.h"
 #include "webrtc/rtc_base/safe_minmax.h"
 
 namespace webrtc {
 
 namespace {
 
 void PredictionError(const Aec3Fft& fft,
                      const FftData& S,
                      rtc::ArrayView<const float> y,
                      std::array<float, kBlockSize>* e,
-                     FftData* E) {
-  std::array<float, kFftLength> s;
-  fft.Ifft(S, &s);
+                     FftData* E,
+                     std::array<float, kBlockSize>* s) {
+  std::array<float, kFftLength> s_scratch;
+  fft.Ifft(S, &s_scratch);
   constexpr float kScale = 1.0f / kFftLengthBy2;
-  std::transform(y.begin(), y.end(), s.begin() + kFftLengthBy2, e->begin(),
-                 [&](float a, float b) { return a - b * kScale; });
+  std::transform(y.begin(), y.end(), s_scratch.begin() + kFftLengthBy2,
+                 e->begin(), [&](float a, float b) { return a - b * kScale; });
   std::for_each(e->begin(), e->end(),
                 [](float& a) { a = rtc::SafeClamp(a, -32768.f, 32767.f); });
   fft.ZeroPaddedFft(*e, E);
+
+  if (s) {
+    for (size_t k = 0; k < s->size(); ++k) {
+      (*s)[k] = kScale * s_scratch[k + kFftLengthBy2];
+    }
+  }
 }
 }  // namespace
 
 Subtractor::Subtractor(ApmDataDumper* data_dumper,
                        Aec3Optimization optimization)
     : fft_(),
       data_dumper_(data_dumper),
       optimization_(optimization),
       main_filter_(kAdaptiveFilterLength, optimization, data_dumper_),
       shadow_filter_(kAdaptiveFilterLength, optimization, data_dumper_) {
   RTC_DCHECK(data_dumper_);
 }
 
-Subtractor::~Subtractor() {}
+Subtractor::~Subtractor() = default;
 
 void Subtractor::HandleEchoPathChange(
     const EchoPathVariability& echo_path_variability) {
   if (echo_path_variability.delay_change) {
     main_filter_.HandleEchoPathChange();
     shadow_filter_.HandleEchoPathChange();
     G_main_.HandleEchoPathChange();
     G_shadow_.HandleEchoPathChange();
   }
 }
 
 void Subtractor::Process(const RenderBuffer& render_buffer,
                          const rtc::ArrayView<const float> capture,
                          const RenderSignalAnalyzer& render_signal_analyzer,
                          const AecState& aec_state,
                          SubtractorOutput* output) {
   RTC_DCHECK_EQ(kBlockSize, capture.size());
   rtc::ArrayView<const float> y = capture;
   FftData& E_main = output->E_main;
   FftData E_shadow;
   std::array<float, kBlockSize>& e_main = output->e_main;
   std::array<float, kBlockSize>& e_shadow = output->e_shadow;
 
   FftData S;
   FftData& G = S;
 
   // Form the output of the main filter.
   main_filter_.Filter(render_buffer, &S);
-  PredictionError(fft_, S, y, &e_main, &E_main);
+  PredictionError(fft_, S, y, &e_main, &E_main, &output->s_main);
 
   // Form the output of the shadow filter.
   shadow_filter_.Filter(render_buffer, &S);
-  PredictionError(fft_, S, y, &e_shadow, &E_shadow);
+  PredictionError(fft_, S, y, &e_shadow, &E_shadow, nullptr);
 
   // Compute spectra for future use.
   E_main.Spectrum(optimization_, &output->E2_main);
   E_shadow.Spectrum(optimization_, &output->E2_shadow);
 
   // Update the main filter.
   G_main_.Compute(render_buffer, render_signal_analyzer, *output, main_filter_,
                   aec_state.SaturatedCapture(), &G);
   main_filter_.Adapt(render_buffer, G);
   data_dumper_->DumpRaw("aec3_subtractor_G_main", G.re);
   data_dumper_->DumpRaw("aec3_subtractor_G_main", G.im);
 
   // Update the shadow filter.
   G_shadow_.Compute(render_buffer, render_signal_analyzer, E_shadow,
                     shadow_filter_.SizePartitions(),
                     aec_state.SaturatedCapture(), &G);
   shadow_filter_.Adapt(render_buffer, G);
 
   data_dumper_->DumpRaw("aec3_subtractor_G_shadow", G.re);
   data_dumper_->DumpRaw("aec3_subtractor_G_shadow", G.im);
 
   main_filter_.DumpFilter("aec3_subtractor_H_main");
   shadow_filter_.DumpFilter("aec3_subtractor_H_shadow");
 }
 
 }  // namespace webrtc