modules/audio_processing/aec3/refined_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 "modules/audio_processing/aec3/refined_filter_update_gain.h"

#include <algorithm>
#include <functional>

#include "modules/audio_processing/aec3/adaptive_fir_filter.h"
#include "modules/audio_processing/aec3/aec3_common.h"
#include "modules/audio_processing/aec3/echo_path_variability.h"
#include "modules/audio_processing/aec3/fft_data.h"
#include "modules/audio_processing/aec3/render_signal_analyzer.h"
#include "modules/audio_processing/aec3/subtractor_output.h"
#include "modules/audio_processing/logging/apm_data_dumper.h"
#include "rtc_base/atomic_ops.h"
#include "rtc_base/checks.h"

namespace webrtc {
namespace {

constexpr float kHErrorInitial = 10000.f;
constexpr int kPoorExcitationCounterInitial = 1000;

}  // namespace

int RefinedFilterUpdateGain::instance_count_ = 0;

RefinedFilterUpdateGain::RefinedFilterUpdateGain(
    const EchoCanceller3Config::Filter::RefinedConfiguration& config,
    size_t config_change_duration_blocks)
    : data_dumper_(
          new ApmDataDumper(rtc::AtomicOps::Increment(&instance_count_))),
      config_change_duration_blocks_(
          static_cast<int>(config_change_duration_blocks)),
      poor_excitation_counter_(kPoorExcitationCounterInitial) {
  SetConfig(config, true);
  H_error_.fill(kHErrorInitial);
  RTC_DCHECK_LT(0, config_change_duration_blocks_);
  one_by_config_change_duration_blocks_ = 1.f / config_change_duration_blocks_;
}

RefinedFilterUpdateGain::~RefinedFilterUpdateGain() {}

void RefinedFilterUpdateGain::HandleEchoPathChange(
    const EchoPathVariability& echo_path_variability) {
  if (echo_path_variability.gain_change) {
    // TODO(bugs.webrtc.org/9526) Handle gain changes.
  }

  if (echo_path_variability.delay_change !=
      EchoPathVariability::DelayAdjustment::kNone) {
    H_error_.fill(kHErrorInitial);
  }

  if (!echo_path_variability.gain_change) {
    poor_excitation_counter_ = kPoorExcitationCounterInitial;
    call_counter_ = 0;
  }
}

void RefinedFilterUpdateGain::Compute(
    const std::array<float, kFftLengthBy2Plus1>& render_power,
    const RenderSignalAnalyzer& render_signal_analyzer,
    const SubtractorOutput& subtractor_output,
    rtc::ArrayView<const float> erl,
    size_t size_partitions,
    bool saturated_capture_signal,
    bool disallow_leakage_diverged,
    FftData* gain_fft) {
  RTC_DCHECK(gain_fft);
  // Introducing shorter notation to improve readability.
  const FftData& E_refined = subtractor_output.E_refined;
  const auto& E2_refined = subtractor_output.E2_refined;
  const auto& E2_coarse = subtractor_output.E2_coarse;
  FftData* G = gain_fft;
  const auto& X2 = render_power;

  ++call_counter_;

  UpdateCurrentConfig();

  if (render_signal_analyzer.PoorSignalExcitation()) {
    poor_excitation_counter_ = 0;
  }

  // Do not update the filter if the render is not sufficiently excited.
  if (++poor_excitation_counter_ < size_partitions ||
      saturated_capture_signal || call_counter_ <= size_partitions) {
    G->re.fill(0.f);
    G->im.fill(0.f);
  } else {
    // Corresponds to WGN of power -39 dBFS.
    std::array<float, kFftLengthBy2Plus1> mu;
    // mu = H_error / (0.5* H_error* X2 + n * E2).
    for (size_t k = 0; k < kFftLengthBy2Plus1; ++k) {
      if (X2[k] >= current_config_.noise_gate) {
        mu[k] = H_error_[k] /
                (0.5f * H_error_[k] * X2[k] + size_partitions * E2_refined[k]);
      } else {
        mu[k] = 0.f;
      }
    }

    // Avoid updating the filter close to narrow bands in the render signals.
    render_signal_analyzer.MaskRegionsAroundNarrowBands(&mu);

    // H_error = H_error - 0.5 * mu * X2 * H_error.
    for (size_t k = 0; k < kFftLengthBy2Plus1; ++k) {
      H_error_[k] -= 0.5f * mu[k] * X2[k] * H_error_[k];
    }

    // G = mu * E.
    for (size_t k = 0; k < kFftLengthBy2Plus1; ++k) {
      G->re[k] = mu[k] * E_refined.re[k];
      G->im[k] = mu[k] * E_refined.im[k];
    }
  }

  // H_error = H_error + factor * erl.
  for (size_t k = 0; k < kFftLengthBy2Plus1; ++k) {
    if (E2_refined[k] <= E2_coarse[k] || disallow_leakage_diverged) {
      H_error_[k] += current_config_.leakage_converged * erl[k];
    } else {
      H_error_[k] += current_config_.leakage_diverged * erl[k];
    }

    H_error_[k] = std::max(H_error_[k], current_config_.error_floor);
    H_error_[k] = std::min(H_error_[k], current_config_.error_ceil);
  }

  data_dumper_->DumpRaw("aec3_refined_gain_H_error", H_error_);
}

void RefinedFilterUpdateGain::UpdateCurrentConfig() {
  RTC_DCHECK_GE(config_change_duration_blocks_, config_change_counter_);
  if (config_change_counter_ > 0) {
    if (--config_change_counter_ > 0) {
      auto average = [](float from, float to, float from_weight) {
        return from * from_weight + to * (1.f - from_weight);
      };

      float change_factor =
          config_change_counter_ * one_by_config_change_duration_blocks_;

      current_config_.leakage_converged =
          average(old_target_config_.leakage_converged,
                  target_config_.leakage_converged, change_factor);
      current_config_.leakage_diverged =
          average(old_target_config_.leakage_diverged,
                  target_config_.leakage_diverged, change_factor);
      current_config_.error_floor =
          average(old_target_config_.error_floor, target_config_.error_floor,
                  change_factor);
      current_config_.error_ceil =
          average(old_target_config_.error_ceil, target_config_.error_ceil,
                  change_factor);
      current_config_.noise_gate =
          average(old_target_config_.noise_gate, target_config_.noise_gate,
                  change_factor);
    } else {
      current_config_ = old_target_config_ = target_config_;
    }
  }
  RTC_DCHECK_LE(0, config_change_counter_);
}

}  // namespace webrtc