modules/video_coding/utility/quality_scaler.cc - src - Git at Google

 /*
  *  Copyright (c) 2014 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/video_coding/utility/quality_scaler.h"

 #include <memory>
 #include <utility>

 #include "rtc_base/checks.h"
 #include "rtc_base/experiments/quality_scaler_settings.h"
 #include "rtc_base/logging.h"
 #include "rtc_base/numerics/exp_filter.h"
 #include "rtc_base/task_queue.h"

 // TODO(kthelgason): Some versions of Android have issues with log2.
 // See https://code.google.com/p/android/issues/detail?id=212634 for details
 #if defined(WEBRTC_ANDROID)
 #define log2(x) (log(x) / log(2))
 #endif

 namespace webrtc {

 namespace {
 // TODO(nisse): Delete, delegate to encoders.
 // Threshold constant used until first downscale (to permit fast rampup).
 static const int kMeasureMs = 2000;
 static const float kSamplePeriodScaleFactor = 2.5;
 static const int kFramedropPercentThreshold = 60;
 static const size_t kMinFramesNeededToScale = 2 * 30;

 }  // namespace

 class QualityScaler::QpSmoother {
  public:
   explicit QpSmoother(float alpha)
       : alpha_(alpha),
         // The initial value of last_sample_ms doesn't matter since the smoother
         // will ignore the time delta for the first update.
         last_sample_ms_(0),
         smoother_(alpha) {}

   absl::optional<int> GetAvg() const {
     float value = smoother_.filtered();
     if (value == rtc::ExpFilter::kValueUndefined) {
       return absl::nullopt;
     }
     return static_cast<int>(value);
   }

   void Add(float sample, int64_t time_sent_us) {
     int64_t now_ms = time_sent_us / 1000;
     smoother_.Apply(static_cast<float>(now_ms - last_sample_ms_), sample);
     last_sample_ms_ = now_ms;
   }

   void Reset() { smoother_.Reset(alpha_); }

  private:
   const float alpha_;
   int64_t last_sample_ms_;
   rtc::ExpFilter smoother_;
 };

 QualityScaler::QualityScaler(rtc::TaskQueue* task_queue,
                              AdaptationObserverInterface* observer,
                              VideoEncoder::QpThresholds thresholds)
     : QualityScaler(task_queue, observer, thresholds, kMeasureMs) {}

 // Protected ctor, should not be called directly.
 QualityScaler::QualityScaler(rtc::TaskQueue* task_queue,
                              AdaptationObserverInterface* observer,
                              VideoEncoder::QpThresholds thresholds,
                              int64_t sampling_period_ms)
     : observer_(observer),
       thresholds_(thresholds),
       sampling_period_ms_(sampling_period_ms),
       fast_rampup_(true),
       // Arbitrarily choose size based on 30 fps for 5 seconds.
       average_qp_(5 * 30),
       framedrop_percent_media_opt_(5 * 30),
       framedrop_percent_all_(5 * 30),
       experiment_enabled_(QualityScalingExperiment::Enabled()),
       observed_enough_frames_(false),
       min_frames_needed_(
           QualityScalerSettings::ParseFromFieldTrials().MinFrames().value_or(
               kMinFramesNeededToScale)),
       initial_scale_factor_(QualityScalerSettings::ParseFromFieldTrials()
                                 .InitialScaleFactor()
                                 .value_or(kSamplePeriodScaleFactor)),
       scale_factor_(
           QualityScalerSettings::ParseFromFieldTrials().ScaleFactor()),
       last_adapted_(false) {
   RTC_DCHECK_RUN_ON(&task_checker_);
   if (experiment_enabled_) {
     config_ = QualityScalingExperiment::GetConfig();
     qp_smoother_high_.reset(new QpSmoother(config_.alpha_high));
     qp_smoother_low_.reset(new QpSmoother(config_.alpha_low));
   }
   RTC_DCHECK(observer_ != nullptr);
   check_qp_task_ = RepeatingTaskHandle::DelayedStart(
       task_queue->Get(), TimeDelta::ms(GetSamplingPeriodMs()), [this]() {
         CheckQp();
         return TimeDelta::ms(GetSamplingPeriodMs());
       });
   RTC_LOG(LS_INFO) << "QP thresholds: low: " << thresholds_.low
                    << ", high: " << thresholds_.high;
 }

 QualityScaler::~QualityScaler() {
   RTC_DCHECK_RUN_ON(&task_checker_);
   check_qp_task_.Stop();
 }

 int64_t QualityScaler::GetSamplingPeriodMs() const {
   RTC_DCHECK_RUN_ON(&task_checker_);
   if (fast_rampup_) {
     return sampling_period_ms_;
   }
   if (experiment_enabled_ && !observed_enough_frames_) {
     // Use half the interval while waiting for enough frames.
     return sampling_period_ms_ / 2;
   }
   if (scale_factor_ && !last_adapted_) {
     // Last check did not result in a AdaptDown/Up, possibly reduce interval.
     return sampling_period_ms_ * scale_factor_.value();
   }
   return sampling_period_ms_ * initial_scale_factor_;
 }

 void QualityScaler::SetQpThresholds(VideoEncoder::QpThresholds thresholds) {
   RTC_DCHECK_RUN_ON(&task_checker_);
   thresholds_ = thresholds;
 }

 void QualityScaler::ReportDroppedFrameByMediaOpt() {
   RTC_DCHECK_RUN_ON(&task_checker_);
   framedrop_percent_media_opt_.AddSample(100);
   framedrop_percent_all_.AddSample(100);
 }

 void QualityScaler::ReportDroppedFrameByEncoder() {
   RTC_DCHECK_RUN_ON(&task_checker_);
   framedrop_percent_all_.AddSample(100);
 }

 void QualityScaler::ReportQp(int qp, int64_t time_sent_us) {
   RTC_DCHECK_RUN_ON(&task_checker_);
   framedrop_percent_media_opt_.AddSample(0);
   framedrop_percent_all_.AddSample(0);
   average_qp_.AddSample(qp);
   if (qp_smoother_high_)
     qp_smoother_high_->Add(qp, time_sent_us);
   if (qp_smoother_low_)
     qp_smoother_low_->Add(qp, time_sent_us);
 }

 void QualityScaler::CheckQp() {
   RTC_DCHECK_RUN_ON(&task_checker_);
   // Should be set through InitEncode -> Should be set by now.
   RTC_DCHECK_GE(thresholds_.low, 0);
   last_adapted_ = false;

   // If we have not observed at least this many frames we can't make a good
   // scaling decision.
   const size_t frames = config_.use_all_drop_reasons
                             ? framedrop_percent_all_.Size()
                             : framedrop_percent_media_opt_.Size();
   if (frames < min_frames_needed_) {
     observed_enough_frames_ = false;
     return;
   }
   observed_enough_frames_ = true;

   // Check if we should scale down due to high frame drop.
   const absl::optional<int> drop_rate =
       config_.use_all_drop_reasons
           ? framedrop_percent_all_.GetAverageRoundedDown()
           : framedrop_percent_media_opt_.GetAverageRoundedDown();
   if (drop_rate && *drop_rate >= kFramedropPercentThreshold) {
     RTC_LOG(LS_INFO) << "Reporting high QP, framedrop percent " << *drop_rate;
     ReportQpHigh();
     return;
   }

   // Check if we should scale up or down based on QP.
   const absl::optional<int> avg_qp_high =
       qp_smoother_high_ ? qp_smoother_high_->GetAvg()
                         : average_qp_.GetAverageRoundedDown();
   const absl::optional<int> avg_qp_low =
       qp_smoother_low_ ? qp_smoother_low_->GetAvg()
                        : average_qp_.GetAverageRoundedDown();
   if (avg_qp_high && avg_qp_low) {
     RTC_LOG(LS_INFO) << "Checking average QP " << *avg_qp_high << " ("
                      << *avg_qp_low << ").";
     if (*avg_qp_high > thresholds_.high) {
       ReportQpHigh();
       return;
     }
     if (*avg_qp_low <= thresholds_.low) {
       // QP has been low. We want to try a higher resolution.
       ReportQpLow();
       return;
     }
   }
 }

 void QualityScaler::ReportQpLow() {
   RTC_DCHECK_RUN_ON(&task_checker_);
   ClearSamples();
   observer_->AdaptUp(AdaptationObserverInterface::AdaptReason::kQuality);
   last_adapted_ = true;
 }

 void QualityScaler::ReportQpHigh() {
   RTC_DCHECK_RUN_ON(&task_checker_);
   ClearSamples();
   observer_->AdaptDown(AdaptationObserverInterface::AdaptReason::kQuality);
   // If we've scaled down, wait longer before scaling up again.
   if (fast_rampup_) {
     fast_rampup_ = false;
   }
   last_adapted_ = true;
 }

 void QualityScaler::ClearSamples() {
   RTC_DCHECK_RUN_ON(&task_checker_);
   framedrop_percent_media_opt_.Reset();
   framedrop_percent_all_.Reset();
   average_qp_.Reset();
   if (qp_smoother_high_)
     qp_smoother_high_->Reset();
   if (qp_smoother_low_)
     qp_smoother_low_->Reset();
 }
 }  // namespace webrtc
	/*
	* Copyright (c) 2014 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/video_coding/utility/quality_scaler.h"

	#include <memory>
	#include <utility>

	#include "rtc_base/checks.h"
	#include "rtc_base/experiments/quality_scaler_settings.h"
	#include "rtc_base/logging.h"
	#include "rtc_base/numerics/exp_filter.h"
	#include "rtc_base/task_queue.h"

	// TODO(kthelgason): Some versions of Android have issues with log2.
	// See https://code.google.com/p/android/issues/detail?id=212634 for details
	#if defined(WEBRTC_ANDROID)
	#define log2(x) (log(x) / log(2))
	#endif

	namespace webrtc {

	namespace {
	// TODO(nisse): Delete, delegate to encoders.
	// Threshold constant used until first downscale (to permit fast rampup).
	static const int kMeasureMs = 2000;
	static const float kSamplePeriodScaleFactor = 2.5;
	static const int kFramedropPercentThreshold = 60;
	static const size_t kMinFramesNeededToScale = 2 * 30;

	} // namespace

	class QualityScaler::QpSmoother {
	public:
	explicit QpSmoother(float alpha)
	: alpha_(alpha),
	// The initial value of last_sample_ms doesn't matter since the smoother
	// will ignore the time delta for the first update.
	last_sample_ms_(0),
	smoother_(alpha) {}

	absl::optional<int> GetAvg() const {
	float value = smoother_.filtered();
	if (value == rtc::ExpFilter::kValueUndefined) {
	return absl::nullopt;
	}
	return static_cast<int>(value);
	}

	void Add(float sample, int64_t time_sent_us) {
	int64_t now_ms = time_sent_us / 1000;
	smoother_.Apply(static_cast<float>(now_ms - last_sample_ms_), sample);
	last_sample_ms_ = now_ms;
	}

	void Reset() { smoother_.Reset(alpha_); }

	private:
	const float alpha_;
	int64_t last_sample_ms_;
	rtc::ExpFilter smoother_;
	};

	QualityScaler::QualityScaler(rtc::TaskQueue* task_queue,
	AdaptationObserverInterface* observer,
	VideoEncoder::QpThresholds thresholds)
	: QualityScaler(task_queue, observer, thresholds, kMeasureMs) {}

	// Protected ctor, should not be called directly.
	QualityScaler::QualityScaler(rtc::TaskQueue* task_queue,
	AdaptationObserverInterface* observer,
	VideoEncoder::QpThresholds thresholds,
	int64_t sampling_period_ms)
	: observer_(observer),
	thresholds_(thresholds),
	sampling_period_ms_(sampling_period_ms),
	fast_rampup_(true),
	// Arbitrarily choose size based on 30 fps for 5 seconds.
	average_qp_(5 * 30),
	framedrop_percent_media_opt_(5 * 30),
	framedrop_percent_all_(5 * 30),
	experiment_enabled_(QualityScalingExperiment::Enabled()),
	observed_enough_frames_(false),
	min_frames_needed_(
	QualityScalerSettings::ParseFromFieldTrials().MinFrames().value_or(
	kMinFramesNeededToScale)),
	initial_scale_factor_(QualityScalerSettings::ParseFromFieldTrials()
	.InitialScaleFactor()
	.value_or(kSamplePeriodScaleFactor)),
	scale_factor_(
	QualityScalerSettings::ParseFromFieldTrials().ScaleFactor()),
	last_adapted_(false) {
	RTC_DCHECK_RUN_ON(&task_checker_);
	if (experiment_enabled_) {
	config_ = QualityScalingExperiment::GetConfig();
	qp_smoother_high_.reset(new QpSmoother(config_.alpha_high));
	qp_smoother_low_.reset(new QpSmoother(config_.alpha_low));
	}
	RTC_DCHECK(observer_ != nullptr);
	check_qp_task_ = RepeatingTaskHandle::DelayedStart(
	task_queue->Get(), TimeDelta::ms(GetSamplingPeriodMs()), [this]() {
	CheckQp();
	return TimeDelta::ms(GetSamplingPeriodMs());
	});
	RTC_LOG(LS_INFO) << "QP thresholds: low: " << thresholds_.low
	<< ", high: " << thresholds_.high;
	}

	QualityScaler::~QualityScaler() {
	RTC_DCHECK_RUN_ON(&task_checker_);
	check_qp_task_.Stop();
	}

	int64_t QualityScaler::GetSamplingPeriodMs() const {
	RTC_DCHECK_RUN_ON(&task_checker_);
	if (fast_rampup_) {
	return sampling_period_ms_;
	}
	if (experiment_enabled_ && !observed_enough_frames_) {
	// Use half the interval while waiting for enough frames.
	return sampling_period_ms_ / 2;
	}
	if (scale_factor_ && !last_adapted_) {
	// Last check did not result in a AdaptDown/Up, possibly reduce interval.
	return sampling_period_ms_ * scale_factor_.value();
	}
	return sampling_period_ms_ * initial_scale_factor_;
	}

	void QualityScaler::SetQpThresholds(VideoEncoder::QpThresholds thresholds) {
	RTC_DCHECK_RUN_ON(&task_checker_);
	thresholds_ = thresholds;
	}

	void QualityScaler::ReportDroppedFrameByMediaOpt() {
	RTC_DCHECK_RUN_ON(&task_checker_);
	framedrop_percent_media_opt_.AddSample(100);
	framedrop_percent_all_.AddSample(100);
	}

	void QualityScaler::ReportDroppedFrameByEncoder() {
	RTC_DCHECK_RUN_ON(&task_checker_);
	framedrop_percent_all_.AddSample(100);
	}

	void QualityScaler::ReportQp(int qp, int64_t time_sent_us) {
	RTC_DCHECK_RUN_ON(&task_checker_);
	framedrop_percent_media_opt_.AddSample(0);
	framedrop_percent_all_.AddSample(0);
	average_qp_.AddSample(qp);
	if (qp_smoother_high_)
	qp_smoother_high_->Add(qp, time_sent_us);
	if (qp_smoother_low_)
	qp_smoother_low_->Add(qp, time_sent_us);
	}

	void QualityScaler::CheckQp() {
	RTC_DCHECK_RUN_ON(&task_checker_);
	// Should be set through InitEncode -> Should be set by now.
	RTC_DCHECK_GE(thresholds_.low, 0);
	last_adapted_ = false;

	// If we have not observed at least this many frames we can't make a good
	// scaling decision.
	const size_t frames = config_.use_all_drop_reasons
	? framedrop_percent_all_.Size()
	: framedrop_percent_media_opt_.Size();
	if (frames < min_frames_needed_) {
	observed_enough_frames_ = false;
	return;
	}
	observed_enough_frames_ = true;

	// Check if we should scale down due to high frame drop.
	const absl::optional<int> drop_rate =
	config_.use_all_drop_reasons
	? framedrop_percent_all_.GetAverageRoundedDown()
	: framedrop_percent_media_opt_.GetAverageRoundedDown();
	if (drop_rate && *drop_rate >= kFramedropPercentThreshold) {
	RTC_LOG(LS_INFO) << "Reporting high QP, framedrop percent " << *drop_rate;
	ReportQpHigh();
	return;
	}

	// Check if we should scale up or down based on QP.
	const absl::optional<int> avg_qp_high =
	qp_smoother_high_ ? qp_smoother_high_->GetAvg()
	: average_qp_.GetAverageRoundedDown();
	const absl::optional<int> avg_qp_low =
	qp_smoother_low_ ? qp_smoother_low_->GetAvg()
	: average_qp_.GetAverageRoundedDown();
	if (avg_qp_high && avg_qp_low) {
	RTC_LOG(LS_INFO) << "Checking average QP " << *avg_qp_high << " ("
	<< *avg_qp_low << ").";
	if (*avg_qp_high > thresholds_.high) {
	ReportQpHigh();
	return;
	}
	if (*avg_qp_low <= thresholds_.low) {
	// QP has been low. We want to try a higher resolution.
	ReportQpLow();
	return;
	}
	}
	}

	void QualityScaler::ReportQpLow() {
	RTC_DCHECK_RUN_ON(&task_checker_);
	ClearSamples();
	observer_->AdaptUp(AdaptationObserverInterface::AdaptReason::kQuality);
	last_adapted_ = true;
	}

	void QualityScaler::ReportQpHigh() {
	RTC_DCHECK_RUN_ON(&task_checker_);
	ClearSamples();
	observer_->AdaptDown(AdaptationObserverInterface::AdaptReason::kQuality);
	// If we've scaled down, wait longer before scaling up again.
	if (fast_rampup_) {
	fast_rampup_ = false;
	}
	last_adapted_ = true;
	}

	void QualityScaler::ClearSamples() {
	RTC_DCHECK_RUN_ON(&task_checker_);
	framedrop_percent_media_opt_.Reset();
	framedrop_percent_all_.Reset();
	average_qp_.Reset();
	if (qp_smoother_high_)
	qp_smoother_high_->Reset();
	if (qp_smoother_low_)
	qp_smoother_low_->Reset();
	}
	} // namespace webrtc