modules/audio_processing/level_controller/level_controller.cc - src/webrtc - Git at Google

 /*
  *  Copyright (c) 2016 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/level_controller/level_controller.h"

 #include <math.h>
 #include <algorithm>
 #include <numeric>

 #include "webrtc/api/array_view.h"
 #include "webrtc/modules/audio_processing/audio_buffer.h"
 #include "webrtc/modules/audio_processing/level_controller/gain_applier.h"
 #include "webrtc/modules/audio_processing/level_controller/gain_selector.h"
 #include "webrtc/modules/audio_processing/level_controller/noise_level_estimator.h"
 #include "webrtc/modules/audio_processing/level_controller/peak_level_estimator.h"
 #include "webrtc/modules/audio_processing/level_controller/saturating_gain_estimator.h"
 #include "webrtc/modules/audio_processing/level_controller/signal_classifier.h"
 #include "webrtc/modules/audio_processing/logging/apm_data_dumper.h"
 #include "webrtc/rtc_base/arraysize.h"
 #include "webrtc/rtc_base/checks.h"
 #include "webrtc/rtc_base/logging.h"
 #include "webrtc/system_wrappers/include/metrics.h"

 namespace webrtc {
 namespace {

 void UpdateAndRemoveDcLevel(float forgetting_factor,
                             float* dc_level,
                             rtc::ArrayView<float> x) {
   RTC_DCHECK(!x.empty());
   float mean =
       std::accumulate(x.begin(), x.end(), 0.0f) / static_cast<float>(x.size());
   *dc_level += forgetting_factor * (mean - *dc_level);

   for (float& v : x) {
     v -= *dc_level;
   }
 }

 float FrameEnergy(const AudioBuffer& audio) {
   float energy = 0.f;
   for (size_t k = 0; k < audio.num_channels(); ++k) {
     float channel_energy =
         std::accumulate(audio.channels_const_f()[k],
                         audio.channels_const_f()[k] + audio.num_frames(), 0,
                         [](float a, float b) -> float { return a + b * b; });
     energy = std::max(channel_energy, energy);
   }
   return energy;
 }

 float PeakLevel(const AudioBuffer& audio) {
   float peak_level = 0.f;
   for (size_t k = 0; k < audio.num_channels(); ++k) {
     auto* channel_peak_level = std::max_element(
         audio.channels_const_f()[k],
         audio.channels_const_f()[k] + audio.num_frames(),
         [](float a, float b) { return std::abs(a) < std::abs(b); });
     peak_level = std::max(*channel_peak_level, peak_level);
   }
   return peak_level;
 }

 const int kMetricsFrameInterval = 1000;

 }  // namespace

 int LevelController::instance_count_ = 0;

 void LevelController::Metrics::Initialize(int sample_rate_hz) {
   RTC_DCHECK(sample_rate_hz == AudioProcessing::kSampleRate8kHz ||
              sample_rate_hz == AudioProcessing::kSampleRate16kHz ||
              sample_rate_hz == AudioProcessing::kSampleRate32kHz ||
              sample_rate_hz == AudioProcessing::kSampleRate48kHz);

   Reset();
   frame_length_ = rtc::CheckedDivExact(sample_rate_hz, 100);
 }

 void LevelController::Metrics::Reset() {
   metrics_frame_counter_ = 0;
   gain_sum_ = 0.f;
   peak_level_sum_ = 0.f;
   noise_energy_sum_ = 0.f;
   max_gain_ = 0.f;
   max_peak_level_ = 0.f;
   max_noise_energy_ = 0.f;
 }

 void LevelController::Metrics::Update(float long_term_peak_level,
                                       float noise_energy,
                                       float gain,
                                       float frame_peak_level) {
   const float kdBFSOffset = 90.3090f;
   gain_sum_ += gain;
   peak_level_sum_ += long_term_peak_level;
   noise_energy_sum_ += noise_energy;
   max_gain_ = std::max(max_gain_, gain);
   max_peak_level_ = std::max(max_peak_level_, long_term_peak_level);
   max_noise_energy_ = std::max(max_noise_energy_, noise_energy);

   ++metrics_frame_counter_;
   if (metrics_frame_counter_ == kMetricsFrameInterval) {
     RTC_DCHECK_LT(0, frame_length_);
     RTC_DCHECK_LT(0, kMetricsFrameInterval);

     const int max_noise_power_dbfs = static_cast<int>(
         10 * log10(max_noise_energy_ / frame_length_ + 1e-10f) - kdBFSOffset);
     RTC_HISTOGRAM_COUNTS("WebRTC.Audio.LevelControl.MaxNoisePower",
                          max_noise_power_dbfs, -90, 0, 50);

     const int average_noise_power_dbfs = static_cast<int>(
         10 * log10(noise_energy_sum_ / (frame_length_ * kMetricsFrameInterval) +
                    1e-10f) -
         kdBFSOffset);
     RTC_HISTOGRAM_COUNTS("WebRTC.Audio.LevelControl.AverageNoisePower",
                          average_noise_power_dbfs, -90, 0, 50);

     const int max_peak_level_dbfs = static_cast<int>(
         10 * log10(max_peak_level_ * max_peak_level_ + 1e-10f) - kdBFSOffset);
     RTC_HISTOGRAM_COUNTS("WebRTC.Audio.LevelControl.MaxPeakLevel",
                          max_peak_level_dbfs, -90, 0, 50);

     const int average_peak_level_dbfs = static_cast<int>(
         10 * log10(peak_level_sum_ * peak_level_sum_ /
                        (kMetricsFrameInterval * kMetricsFrameInterval) +
                    1e-10f) -
         kdBFSOffset);
     RTC_HISTOGRAM_COUNTS("WebRTC.Audio.LevelControl.AveragePeakLevel",
                          average_peak_level_dbfs, -90, 0, 50);

     RTC_DCHECK_LE(1.f, max_gain_);
     RTC_DCHECK_LE(1.f, gain_sum_ / kMetricsFrameInterval);

     const int max_gain_db = static_cast<int>(10 * log10(max_gain_ * max_gain_));
     RTC_HISTOGRAM_COUNTS("WebRTC.Audio.LevelControl.MaxGain", max_gain_db, 0,
                          33, 30);

     const int average_gain_db = static_cast<int>(
         10 * log10(gain_sum_ * gain_sum_ /
                    (kMetricsFrameInterval * kMetricsFrameInterval)));
     RTC_HISTOGRAM_COUNTS("WebRTC.Audio.LevelControl.AverageGain",
                          average_gain_db, 0, 33, 30);

     const int long_term_peak_level_dbfs = static_cast<int>(
         10 * log10(long_term_peak_level * long_term_peak_level + 1e-10f) -
         kdBFSOffset);

     const int frame_peak_level_dbfs = static_cast<int>(
         10 * log10(frame_peak_level * frame_peak_level + 1e-10f) - kdBFSOffset);

     LOG(LS_INFO) << "Level Controller metrics: {"
                  << "Max noise power: " << max_noise_power_dbfs << " dBFS, "
                  << "Average noise power: " << average_noise_power_dbfs
                  << " dBFS, "
                  << "Max long term peak level: " << max_peak_level_dbfs
                  << " dBFS, "
                  << "Average long term peak level: " << average_peak_level_dbfs
                  << " dBFS, "
                  << "Max gain: " << max_gain_db << " dB, "
                  << "Average gain: " << average_gain_db << " dB, "
                  << "Long term peak level: " << long_term_peak_level_dbfs
                  << " dBFS, "
                  << "Last frame peak level: " << frame_peak_level_dbfs
                  << " dBFS"
                  << "}";

     Reset();
   }
 }

 LevelController::LevelController()
     : data_dumper_(new ApmDataDumper(instance_count_)),
       gain_applier_(data_dumper_.get()),
       signal_classifier_(data_dumper_.get()),
       peak_level_estimator_(kTargetLcPeakLeveldBFS) {
   Initialize(AudioProcessing::kSampleRate48kHz);
   ++instance_count_;
 }

 LevelController::~LevelController() {}

 void LevelController::Initialize(int sample_rate_hz) {
   RTC_DCHECK(sample_rate_hz == AudioProcessing::kSampleRate8kHz ||
              sample_rate_hz == AudioProcessing::kSampleRate16kHz ||
              sample_rate_hz == AudioProcessing::kSampleRate32kHz ||
              sample_rate_hz == AudioProcessing::kSampleRate48kHz);
   data_dumper_->InitiateNewSetOfRecordings();
   gain_selector_.Initialize(sample_rate_hz);
   gain_applier_.Initialize(sample_rate_hz);
   signal_classifier_.Initialize(sample_rate_hz);
   noise_level_estimator_.Initialize(sample_rate_hz);
   peak_level_estimator_.Initialize(config_.initial_peak_level_dbfs);
   saturating_gain_estimator_.Initialize();
   metrics_.Initialize(sample_rate_hz);

   last_gain_ = 1.0f;
   sample_rate_hz_ = rtc::Optional<int>(sample_rate_hz);
   dc_forgetting_factor_ = 0.01f * sample_rate_hz / 48000.f;
   std::fill(dc_level_, dc_level_ + arraysize(dc_level_), 0.f);
 }

 void LevelController::Process(AudioBuffer* audio) {
   RTC_DCHECK_LT(0, audio->num_channels());
   RTC_DCHECK_GE(2, audio->num_channels());
   RTC_DCHECK_NE(0.f, dc_forgetting_factor_);
   RTC_DCHECK(sample_rate_hz_);
   data_dumper_->DumpWav("lc_input", audio->num_frames(),
                         audio->channels_const_f()[0], *sample_rate_hz_, 1);

   // Remove DC level.
   for (size_t k = 0; k < audio->num_channels(); ++k) {
     UpdateAndRemoveDcLevel(
         dc_forgetting_factor_, &dc_level_[k],
         rtc::ArrayView<float>(audio->channels_f()[k], audio->num_frames()));
   }

   SignalClassifier::SignalType signal_type;
   signal_classifier_.Analyze(*audio, &signal_type);
   int tmp = static_cast<int>(signal_type);
   data_dumper_->DumpRaw("lc_signal_type", 1, &tmp);

   // Estimate the noise energy.
   float noise_energy =
       noise_level_estimator_.Analyze(signal_type, FrameEnergy(*audio));

   // Estimate the overall signal peak level.
   const float frame_peak_level = PeakLevel(*audio);
   const float long_term_peak_level =
       peak_level_estimator_.Analyze(signal_type, frame_peak_level);

   float saturating_gain = saturating_gain_estimator_.GetGain();

   // Compute the new gain to apply.
   last_gain_ =
       gain_selector_.GetNewGain(long_term_peak_level, noise_energy,
                                 saturating_gain, gain_jumpstart_, signal_type);

   // Unflag the jumpstart of the gain as it should only happen once.
   gain_jumpstart_ = false;

   // Apply the gain to the signal.
   int num_saturations = gain_applier_.Process(last_gain_, audio);

   // Estimate the gain that saturates the overall signal.
   saturating_gain_estimator_.Update(last_gain_, num_saturations);

   // Update the metrics.
   metrics_.Update(long_term_peak_level, noise_energy, last_gain_,
                   frame_peak_level);

   data_dumper_->DumpRaw("lc_selected_gain", 1, &last_gain_);
   data_dumper_->DumpRaw("lc_noise_energy", 1, &noise_energy);
   data_dumper_->DumpRaw("lc_peak_level", 1, &long_term_peak_level);
   data_dumper_->DumpRaw("lc_saturating_gain", 1, &saturating_gain);

   data_dumper_->DumpWav("lc_output", audio->num_frames(),
                         audio->channels_f()[0], *sample_rate_hz_, 1);
 }

 void LevelController::ApplyConfig(
     const AudioProcessing::Config::LevelController& config) {
   RTC_DCHECK(Validate(config));
   config_ = config;
   peak_level_estimator_.Initialize(config_.initial_peak_level_dbfs);
   gain_jumpstart_ = true;
 }

 std::string LevelController::ToString(
     const AudioProcessing::Config::LevelController& config) {
   std::stringstream ss;
   ss << "{"
      << "enabled: " << (config.enabled ? "true" : "false") << ", "
      << "initial_peak_level_dbfs: " << config.initial_peak_level_dbfs << "}";
   return ss.str();
 }

 bool LevelController::Validate(
     const AudioProcessing::Config::LevelController& config) {
   return (config.initial_peak_level_dbfs <
               std::numeric_limits<float>::epsilon() &&
           config.initial_peak_level_dbfs >
               -(100.f + std::numeric_limits<float>::epsilon()));
 }

 }  // namespace webrtc
	/*
	* Copyright (c) 2016 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/level_controller/level_controller.h"

	#include <math.h>
	#include <algorithm>
	#include <numeric>

	#include "webrtc/api/array_view.h"
	#include "webrtc/modules/audio_processing/audio_buffer.h"
	#include "webrtc/modules/audio_processing/level_controller/gain_applier.h"
	#include "webrtc/modules/audio_processing/level_controller/gain_selector.h"
	#include "webrtc/modules/audio_processing/level_controller/noise_level_estimator.h"
	#include "webrtc/modules/audio_processing/level_controller/peak_level_estimator.h"
	#include "webrtc/modules/audio_processing/level_controller/saturating_gain_estimator.h"
	#include "webrtc/modules/audio_processing/level_controller/signal_classifier.h"
	#include "webrtc/modules/audio_processing/logging/apm_data_dumper.h"
	#include "webrtc/rtc_base/arraysize.h"
	#include "webrtc/rtc_base/checks.h"
	#include "webrtc/rtc_base/logging.h"
	#include "webrtc/system_wrappers/include/metrics.h"

	namespace webrtc {
	namespace {

	void UpdateAndRemoveDcLevel(float forgetting_factor,
	float* dc_level,
	rtc::ArrayView<float> x) {
	RTC_DCHECK(!x.empty());
	float mean =
	std::accumulate(x.begin(), x.end(), 0.0f) / static_cast<float>(x.size());
	dc_level += forgetting_factor (mean - *dc_level);

	for (float& v : x) {
	v -= *dc_level;
	}
	}

	float FrameEnergy(const AudioBuffer& audio) {
	float energy = 0.f;
	for (size_t k = 0; k < audio.num_channels(); ++k) {
	float channel_energy =
	std::accumulate(audio.channels_const_f()[k],
	audio.channels_const_f()[k] + audio.num_frames(), 0,
	[](float a, float b) -> float { return a + b * b; });
	energy = std::max(channel_energy, energy);
	}
	return energy;
	}

	float PeakLevel(const AudioBuffer& audio) {
	float peak_level = 0.f;
	for (size_t k = 0; k < audio.num_channels(); ++k) {
	auto* channel_peak_level = std::max_element(
	audio.channels_const_f()[k],
	audio.channels_const_f()[k] + audio.num_frames(),
	[](float a, float b) { return std::abs(a) < std::abs(b); });
	peak_level = std::max(*channel_peak_level, peak_level);
	}
	return peak_level;
	}

	const int kMetricsFrameInterval = 1000;

	} // namespace

	int LevelController::instance_count_ = 0;

	void LevelController::Metrics::Initialize(int sample_rate_hz) {
	RTC_DCHECK(sample_rate_hz == AudioProcessing::kSampleRate8kHz \|\|
	sample_rate_hz == AudioProcessing::kSampleRate16kHz \|\|
	sample_rate_hz == AudioProcessing::kSampleRate32kHz \|\|
	sample_rate_hz == AudioProcessing::kSampleRate48kHz);

	Reset();
	frame_length_ = rtc::CheckedDivExact(sample_rate_hz, 100);
	}

	void LevelController::Metrics::Reset() {
	metrics_frame_counter_ = 0;
	gain_sum_ = 0.f;
	peak_level_sum_ = 0.f;
	noise_energy_sum_ = 0.f;
	max_gain_ = 0.f;
	max_peak_level_ = 0.f;
	max_noise_energy_ = 0.f;
	}

	void LevelController::Metrics::Update(float long_term_peak_level,
	float noise_energy,
	float gain,
	float frame_peak_level) {
	const float kdBFSOffset = 90.3090f;
	gain_sum_ += gain;
	peak_level_sum_ += long_term_peak_level;
	noise_energy_sum_ += noise_energy;
	max_gain_ = std::max(max_gain_, gain);
	max_peak_level_ = std::max(max_peak_level_, long_term_peak_level);
	max_noise_energy_ = std::max(max_noise_energy_, noise_energy);

	++metrics_frame_counter_;
	if (metrics_frame_counter_ == kMetricsFrameInterval) {
	RTC_DCHECK_LT(0, frame_length_);
	RTC_DCHECK_LT(0, kMetricsFrameInterval);

	const int max_noise_power_dbfs = static_cast<int>(
	10 * log10(max_noise_energy_ / frame_length_ + 1e-10f) - kdBFSOffset);
	RTC_HISTOGRAM_COUNTS("WebRTC.Audio.LevelControl.MaxNoisePower",
	max_noise_power_dbfs, -90, 0, 50);

	const int average_noise_power_dbfs = static_cast<int>(
	10 * log10(noise_energy_sum_ / (frame_length_ * kMetricsFrameInterval) +
	1e-10f) -
	kdBFSOffset);
	RTC_HISTOGRAM_COUNTS("WebRTC.Audio.LevelControl.AverageNoisePower",
	average_noise_power_dbfs, -90, 0, 50);

	const int max_peak_level_dbfs = static_cast<int>(
	10 * log10(max_peak_level_ * max_peak_level_ + 1e-10f) - kdBFSOffset);
	RTC_HISTOGRAM_COUNTS("WebRTC.Audio.LevelControl.MaxPeakLevel",
	max_peak_level_dbfs, -90, 0, 50);

	const int average_peak_level_dbfs = static_cast<int>(
	10 * log10(peak_level_sum_ * peak_level_sum_ /
	(kMetricsFrameInterval * kMetricsFrameInterval) +
	1e-10f) -
	kdBFSOffset);
	RTC_HISTOGRAM_COUNTS("WebRTC.Audio.LevelControl.AveragePeakLevel",
	average_peak_level_dbfs, -90, 0, 50);

	RTC_DCHECK_LE(1.f, max_gain_);
	RTC_DCHECK_LE(1.f, gain_sum_ / kMetricsFrameInterval);

	const int max_gain_db = static_cast<int>(10 * log10(max_gain_ * max_gain_));
	RTC_HISTOGRAM_COUNTS("WebRTC.Audio.LevelControl.MaxGain", max_gain_db, 0,
	33, 30);

	const int average_gain_db = static_cast<int>(
	10 * log10(gain_sum_ * gain_sum_ /
	(kMetricsFrameInterval * kMetricsFrameInterval)));
	RTC_HISTOGRAM_COUNTS("WebRTC.Audio.LevelControl.AverageGain",
	average_gain_db, 0, 33, 30);

	const int long_term_peak_level_dbfs = static_cast<int>(
	10 * log10(long_term_peak_level * long_term_peak_level + 1e-10f) -
	kdBFSOffset);

	const int frame_peak_level_dbfs = static_cast<int>(
	10 * log10(frame_peak_level * frame_peak_level + 1e-10f) - kdBFSOffset);

	LOG(LS_INFO) << "Level Controller metrics: {"
	<< "Max noise power: " << max_noise_power_dbfs << " dBFS, "
	<< "Average noise power: " << average_noise_power_dbfs
	<< " dBFS, "
	<< "Max long term peak level: " << max_peak_level_dbfs
	<< " dBFS, "
	<< "Average long term peak level: " << average_peak_level_dbfs
	<< " dBFS, "
	<< "Max gain: " << max_gain_db << " dB, "
	<< "Average gain: " << average_gain_db << " dB, "
	<< "Long term peak level: " << long_term_peak_level_dbfs
	<< " dBFS, "
	<< "Last frame peak level: " << frame_peak_level_dbfs
	<< " dBFS"
	<< "}";

	Reset();
	}
	}

	LevelController::LevelController()
	: data_dumper_(new ApmDataDumper(instance_count_)),
	gain_applier_(data_dumper_.get()),
	signal_classifier_(data_dumper_.get()),
	peak_level_estimator_(kTargetLcPeakLeveldBFS) {
	Initialize(AudioProcessing::kSampleRate48kHz);
	++instance_count_;
	}

	LevelController::~LevelController() {}

	void LevelController::Initialize(int sample_rate_hz) {
	RTC_DCHECK(sample_rate_hz == AudioProcessing::kSampleRate8kHz \|\|
	sample_rate_hz == AudioProcessing::kSampleRate16kHz \|\|
	sample_rate_hz == AudioProcessing::kSampleRate32kHz \|\|
	sample_rate_hz == AudioProcessing::kSampleRate48kHz);
	data_dumper_->InitiateNewSetOfRecordings();
	gain_selector_.Initialize(sample_rate_hz);
	gain_applier_.Initialize(sample_rate_hz);
	signal_classifier_.Initialize(sample_rate_hz);
	noise_level_estimator_.Initialize(sample_rate_hz);
	peak_level_estimator_.Initialize(config_.initial_peak_level_dbfs);
	saturating_gain_estimator_.Initialize();
	metrics_.Initialize(sample_rate_hz);

	last_gain_ = 1.0f;
	sample_rate_hz_ = rtc::Optional<int>(sample_rate_hz);
	dc_forgetting_factor_ = 0.01f * sample_rate_hz / 48000.f;
	std::fill(dc_level_, dc_level_ + arraysize(dc_level_), 0.f);
	}

	void LevelController::Process(AudioBuffer* audio) {
	RTC_DCHECK_LT(0, audio->num_channels());
	RTC_DCHECK_GE(2, audio->num_channels());
	RTC_DCHECK_NE(0.f, dc_forgetting_factor_);
	RTC_DCHECK(sample_rate_hz_);
	data_dumper_->DumpWav("lc_input", audio->num_frames(),
	audio->channels_const_f()[0], *sample_rate_hz_, 1);

	// Remove DC level.
	for (size_t k = 0; k < audio->num_channels(); ++k) {
	UpdateAndRemoveDcLevel(
	dc_forgetting_factor_, &dc_level_[k],
	rtc::ArrayView<float>(audio->channels_f()[k], audio->num_frames()));
	}

	SignalClassifier::SignalType signal_type;
	signal_classifier_.Analyze(*audio, &signal_type);
	int tmp = static_cast<int>(signal_type);
	data_dumper_->DumpRaw("lc_signal_type", 1, &tmp);

	// Estimate the noise energy.
	float noise_energy =
	noise_level_estimator_.Analyze(signal_type, FrameEnergy(*audio));

	// Estimate the overall signal peak level.
	const float frame_peak_level = PeakLevel(*audio);
	const float long_term_peak_level =
	peak_level_estimator_.Analyze(signal_type, frame_peak_level);

	float saturating_gain = saturating_gain_estimator_.GetGain();

	// Compute the new gain to apply.
	last_gain_ =
	gain_selector_.GetNewGain(long_term_peak_level, noise_energy,
	saturating_gain, gain_jumpstart_, signal_type);

	// Unflag the jumpstart of the gain as it should only happen once.
	gain_jumpstart_ = false;

	// Apply the gain to the signal.
	int num_saturations = gain_applier_.Process(last_gain_, audio);

	// Estimate the gain that saturates the overall signal.
	saturating_gain_estimator_.Update(last_gain_, num_saturations);

	// Update the metrics.
	metrics_.Update(long_term_peak_level, noise_energy, last_gain_,
	frame_peak_level);

	data_dumper_->DumpRaw("lc_selected_gain", 1, &last_gain_);
	data_dumper_->DumpRaw("lc_noise_energy", 1, &noise_energy);
	data_dumper_->DumpRaw("lc_peak_level", 1, &long_term_peak_level);
	data_dumper_->DumpRaw("lc_saturating_gain", 1, &saturating_gain);

	data_dumper_->DumpWav("lc_output", audio->num_frames(),
	audio->channels_f()[0], *sample_rate_hz_, 1);
	}

	void LevelController::ApplyConfig(
	const AudioProcessing::Config::LevelController& config) {
	RTC_DCHECK(Validate(config));
	config_ = config;
	peak_level_estimator_.Initialize(config_.initial_peak_level_dbfs);
	gain_jumpstart_ = true;
	}

	std::string LevelController::ToString(
	const AudioProcessing::Config::LevelController& config) {
	std::stringstream ss;
	ss << "{"
	<< "enabled: " << (config.enabled ? "true" : "false") << ", "
	<< "initial_peak_level_dbfs: " << config.initial_peak_level_dbfs << "}";
	return ss.str();
	}

	bool LevelController::Validate(
	const AudioProcessing::Config::LevelController& config) {
	return (config.initial_peak_level_dbfs <
	std::numeric_limits<float>::epsilon() &&
	config.initial_peak_level_dbfs >
	-(100.f + std::numeric_limits<float>::epsilon()));
	}

	} // namespace webrtc