modules/audio_processing/aec3/echo_remover.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/echo_remover.h"

#include <algorithm>
#include <memory>
#include <numeric>
#include <string>

#include "webrtc/base/array_view.h"
#include "webrtc/base/atomicops.h"
#include "webrtc/base/constructormagic.h"
#include "webrtc/modules/audio_processing/aec3/aec3_common.h"
#include "webrtc/modules/audio_processing/aec3/aec_state.h"
#include "webrtc/modules/audio_processing/aec3/comfort_noise_generator.h"
#include "webrtc/modules/audio_processing/aec3/echo_path_variability.h"
#include "webrtc/modules/audio_processing/aec3/echo_remover_metrics.h"
#include "webrtc/modules/audio_processing/aec3/fft_buffer.h"
#include "webrtc/modules/audio_processing/aec3/fft_data.h"
#include "webrtc/modules/audio_processing/aec3/output_selector.h"
#include "webrtc/modules/audio_processing/aec3/power_echo_model.h"
#include "webrtc/modules/audio_processing/aec3/render_delay_buffer.h"
#include "webrtc/modules/audio_processing/aec3/residual_echo_estimator.h"
#include "webrtc/modules/audio_processing/aec3/subtractor.h"
#include "webrtc/modules/audio_processing/aec3/suppression_filter.h"
#include "webrtc/modules/audio_processing/aec3/suppression_gain.h"
#include "webrtc/modules/audio_processing/logging/apm_data_dumper.h"

namespace webrtc {

namespace {

void LinearEchoPower(const FftData& E,
                     const FftData& Y,
                     std::array<float, kFftLengthBy2Plus1>* S2) {
  for (size_t k = 0; k < E.re.size(); ++k) {
    (*S2)[k] = (Y.re[k] - E.re[k]) * (Y.re[k] - E.re[k]) +
               (Y.im[k] - E.im[k]) * (Y.im[k] - E.im[k]);
  }
}

float BlockPower(const std::array<float, kBlockSize> x) {
  return std::accumulate(x.begin(), x.end(), 0.f,
                         [](float a, float b) -> float { return a + b * b; });
}

// Class for removing the echo from the capture signal.
class EchoRemoverImpl final : public EchoRemover {
 public:
  explicit EchoRemoverImpl(int sample_rate_hz);
  ~EchoRemoverImpl() override;

  // Removes the echo from a block of samples from the capture signal. The
  // supplied render signal is assumed to be pre-aligned with the capture
  // signal.
  void ProcessBlock(
      const rtc::Optional<size_t>& external_echo_path_delay_estimate,
      const EchoPathVariability& echo_path_variability,
      bool capture_signal_saturation,
      const std::vector<std::vector<float>>& render,
      std::vector<std::vector<float>>* capture) override;

  // Updates the status on whether echo leakage is detected in the output of the
  // echo remover.
  void UpdateEchoLeakageStatus(bool leakage_detected) override {
    echo_leakage_detected_ = leakage_detected;
  }

 private:
  static int instance_count_;
  const Aec3Fft fft_;
  std::unique_ptr<ApmDataDumper> data_dumper_;
  const Aec3Optimization optimization_;
  const int sample_rate_hz_;
  Subtractor subtractor_;
  SuppressionGain suppression_gain_;
  ComfortNoiseGenerator cng_;
  SuppressionFilter suppression_filter_;
  PowerEchoModel power_echo_model_;
  FftBuffer X_buffer_;
  RenderSignalAnalyzer render_signal_analyzer_;
  OutputSelector output_selector_;
  ResidualEchoEstimator residual_echo_estimator_;
  bool echo_leakage_detected_ = false;
  std::array<float, kBlockSize> x_old_;
  AecState aec_state_;
  EchoRemoverMetrics metrics_;

  RTC_DISALLOW_COPY_AND_ASSIGN(EchoRemoverImpl);
};

int EchoRemoverImpl::instance_count_ = 0;

EchoRemoverImpl::EchoRemoverImpl(int sample_rate_hz)
    : fft_(),
      data_dumper_(
          new ApmDataDumper(rtc::AtomicOps::Increment(&instance_count_))),
      optimization_(DetectOptimization()),
      sample_rate_hz_(sample_rate_hz),
      subtractor_(data_dumper_.get(), optimization_),
      suppression_gain_(optimization_),
      cng_(optimization_),
      suppression_filter_(sample_rate_hz_),
      X_buffer_(optimization_,
                std::max(subtractor_.MinFarendBufferLength(),
                         power_echo_model_.MinFarendBufferLength()),
                subtractor_.NumBlocksInRenderSums()) {
  RTC_DCHECK(ValidFullBandRate(sample_rate_hz));
  x_old_.fill(0.f);
}

EchoRemoverImpl::~EchoRemoverImpl() = default;

void EchoRemoverImpl::ProcessBlock(
    const rtc::Optional<size_t>& echo_path_delay_samples,
    const EchoPathVariability& echo_path_variability,
    bool capture_signal_saturation,
    const std::vector<std::vector<float>>& render,
    std::vector<std::vector<float>>* capture) {
  const std::vector<std::vector<float>>& x = render;
  std::vector<std::vector<float>>* y = capture;

  RTC_DCHECK(y);
  RTC_DCHECK_EQ(x.size(), NumBandsForRate(sample_rate_hz_));
  RTC_DCHECK_EQ(y->size(), NumBandsForRate(sample_rate_hz_));
  RTC_DCHECK_EQ(x[0].size(), kBlockSize);
  RTC_DCHECK_EQ((*y)[0].size(), kBlockSize);
  const std::vector<float>& x0 = x[0];
  std::vector<float>& y0 = (*y)[0];

  data_dumper_->DumpWav("aec3_processblock_capture_input", kBlockSize, &y0[0],
                        LowestBandRate(sample_rate_hz_), 1);
  data_dumper_->DumpWav("aec3_processblock_render_input", kBlockSize, &x0[0],
                        LowestBandRate(sample_rate_hz_), 1);

  aec_state_.UpdateCaptureSaturation(capture_signal_saturation);

  if (echo_path_variability.AudioPathChanged()) {
    subtractor_.HandleEchoPathChange(echo_path_variability);
    power_echo_model_.HandleEchoPathChange(echo_path_variability);
    residual_echo_estimator_.HandleEchoPathChange(echo_path_variability);
  }

  std::array<float, kFftLengthBy2Plus1> Y2;
  std::array<float, kFftLengthBy2Plus1> S2_power;
  std::array<float, kFftLengthBy2Plus1> R2;
  std::array<float, kFftLengthBy2Plus1> S2_linear;
  std::array<float, kFftLengthBy2Plus1> G;
  FftData X;
  FftData Y;
  FftData comfort_noise;
  FftData high_band_comfort_noise;
  SubtractorOutput subtractor_output;
  FftData& E_main = subtractor_output.E_main;
  auto& E2_main = subtractor_output.E2_main;
  auto& E2_shadow = subtractor_output.E2_shadow;
  auto& e_main = subtractor_output.e_main;
  auto& e_shadow = subtractor_output.e_shadow;

  // Update the render signal buffer.
  fft_.PaddedFft(x0, x_old_, &X);
  X_buffer_.Insert(X);

  // Analyze the render signal.
  render_signal_analyzer_.Update(X_buffer_, aec_state_.FilterDelay());

  // Perform linear echo cancellation.
  subtractor_.Process(X_buffer_, y0, render_signal_analyzer_,
                      aec_state_.SaturatedCapture(), &subtractor_output);

  // Compute spectra.
  fft_.ZeroPaddedFft(y0, &Y);
  LinearEchoPower(E_main, Y, &S2_linear);
  Y.Spectrum(optimization_, &Y2);

  // Update the AEC state information.
  aec_state_.Update(subtractor_.FilterFrequencyResponse(),
                    echo_path_delay_samples, X_buffer_, E2_main, E2_shadow, Y2,
                    x0, echo_path_variability, echo_leakage_detected_);

  // Use the power model to estimate the echo.
  power_echo_model_.EstimateEcho(X_buffer_, Y2, aec_state_, &S2_power);

  // Choose the linear output.
  output_selector_.FormLinearOutput(e_main, y0);
  data_dumper_->DumpWav("aec3_output_linear", kBlockSize, &y0[0],
                        LowestBandRate(sample_rate_hz_), 1);
  const auto& E2 = output_selector_.UseSubtractorOutput() ? E2_main : Y2;

  // Estimate the residual echo power.
  residual_echo_estimator_.Estimate(
      output_selector_.UseSubtractorOutput(), aec_state_, X_buffer_,
      subtractor_.FilterFrequencyResponse(), E2_main, E2_shadow, S2_linear,
      S2_power, Y2, &R2);

  // Estimate the comfort noise.
  cng_.Compute(aec_state_, Y2, &comfort_noise, &high_band_comfort_noise);

  // Detect basic doubletalk.
  const bool doubletalk = BlockPower(e_shadow) < BlockPower(e_main);

  // A choose and apply echo suppression gain.
  suppression_gain_.GetGain(E2, R2, cng_.NoiseSpectrum(),
                            doubletalk ? 0.001f : 0.0001f, &G);
  suppression_filter_.ApplyGain(comfort_noise, high_band_comfort_noise, G, y);

  // Update the metrics.
  metrics_.Update(aec_state_, cng_.NoiseSpectrum(), G);

  // Debug outputs for the purpose of development and analysis.
  data_dumper_->DumpRaw("aec3_N2", cng_.NoiseSpectrum());
  data_dumper_->DumpRaw("aec3_suppressor_gain", G);
  data_dumper_->DumpWav("aec3_output",
                        rtc::ArrayView<const float>(&y0[0], kBlockSize),
                        LowestBandRate(sample_rate_hz_), 1);
  data_dumper_->DumpRaw("aec3_using_subtractor_output",
                        output_selector_.UseSubtractorOutput() ? 1 : 0);
  data_dumper_->DumpRaw("aec3_doubletalk", doubletalk ? 1 : 0);
  data_dumper_->DumpRaw("aec3_E2", E2);
  data_dumper_->DumpRaw("aec3_E2_main", E2_main);
  data_dumper_->DumpRaw("aec3_E2_shadow", E2_shadow);
  data_dumper_->DumpRaw("aec3_S2_linear", S2_linear);
  data_dumper_->DumpRaw("aec3_S2_power", S2_power);
  data_dumper_->DumpRaw("aec3_Y2", Y2);
  data_dumper_->DumpRaw("aec3_R2", R2);
  data_dumper_->DumpRaw("aec3_erle", aec_state_.Erle());
  data_dumper_->DumpRaw("aec3_erl", aec_state_.Erl());
  data_dumper_->DumpRaw("aec3_reliable_filter_bands",
                        aec_state_.BandsWithReliableFilter());
  data_dumper_->DumpRaw("aec3_active_render", aec_state_.ActiveRender());
  data_dumper_->DumpRaw("aec3_model_based_aec_feasible",
                        aec_state_.ModelBasedAecFeasible());
  data_dumper_->DumpRaw("aec3_usable_linear_estimate",
                        aec_state_.UsableLinearEstimate());
  data_dumper_->DumpRaw(
      "aec3_filter_delay",
      aec_state_.FilterDelay() ? *aec_state_.FilterDelay() : -1);
  data_dumper_->DumpRaw(
      "aec3_external_delay",
      aec_state_.ExternalDelay() ? *aec_state_.ExternalDelay() : -1);
  data_dumper_->DumpRaw("aec3_capture_saturation",
                        aec_state_.SaturatedCapture() ? 1 : 0);
}

}  // namespace

EchoRemover* EchoRemover::Create(int sample_rate_hz) {
  return new EchoRemoverImpl(sample_rate_hz);
}

}  // namespace webrtc