quality_scaler.h - mozsearch

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/*

 *  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.

*/

#ifndef MODULES_VIDEO_CODING_UTILITY_QUALITY_SCALER_H_

#define MODULES_VIDEO_CODING_UTILITY_QUALITY_SCALER_H_

#include <stddef.h>

#include <stdint.h>

#include <memory>

#include <optional>

#include "api/field_trials_view.h"

#include "api/scoped_refptr.h"

#include "api/sequence_checker.h"

#include "api/video_codecs/video_encoder.h"

#include "rtc_base/experiments/quality_scaling_experiment.h"

#include "rtc_base/numerics/moving_average.h"

#include "rtc_base/ref_count.h"

#include "rtc_base/system/no_unique_address.h"

namespace webrtc {

class QualityScalerQpUsageHandlerCallbackInterface;

class QualityScalerQpUsageHandlerInterface;

// QualityScaler runs asynchronously and monitors QP values of encoded frames.

// It holds a reference to a QualityScalerQpUsageHandlerInterface implementation

// to signal an overuse or underuse of QP (which indicate a desire to scale the

// video stream down or up).

class QualityScaler {

 public:

  // Construct a QualityScaler with given `thresholds` and `handler`.

  // This starts the quality scaler periodically checking what the average QP

  // has been recently.

  QualityScaler(QualityScalerQpUsageHandlerInterface* handler,

                VideoEncoder::QpThresholds thresholds,

                const FieldTrialsView& field_trials);

  virtual ~QualityScaler();

  // Should be called each time a frame is dropped at encoding.

  void ReportDroppedFrameByMediaOpt();

  void ReportDroppedFrameByEncoder();

  // Inform the QualityScaler of the last seen QP.

  void ReportQp(int qp, int64_t time_sent_us);

  void SetQpThresholds(VideoEncoder::QpThresholds thresholds);

  // The following members declared protected for testing purposes.

 protected:

  QualityScaler(QualityScalerQpUsageHandlerInterface* handler,

                VideoEncoder::QpThresholds thresholds,

                const FieldTrialsView& field_trials,

                int64_t sampling_period_ms);

 private:

  class QpSmoother;

  class CheckQpTask;

  class CheckQpTaskHandlerCallback;

  enum class CheckQpResult {

    kInsufficientSamples,

    kNormalQp,

    kHighQp,

    kLowQp,

};

  // Starts checking for QP in a delayed task. When the resulting CheckQpTask

  // completes, it will invoke this method again, ensuring that we always

  // periodically check for QP. See CheckQpTask for more details. We never run

  // more than one CheckQpTask at a time.

  void StartNextCheckQpTask();

  CheckQpResult CheckQp() const;

  void ClearSamples();

  std::unique_ptr<CheckQpTask> pending_qp_task_ RTC_GUARDED_BY(&task_checker_);

  QualityScalerQpUsageHandlerInterface* const handler_

      RTC_GUARDED_BY(&task_checker_);

  RTC_NO_UNIQUE_ADDRESS SequenceChecker task_checker_;

  VideoEncoder::QpThresholds thresholds_ RTC_GUARDED_BY(&task_checker_);

  const int64_t sampling_period_ms_;

  bool fast_rampup_ RTC_GUARDED_BY(&task_checker_);

  rtc::MovingAverage average_qp_ RTC_GUARDED_BY(&task_checker_);

  rtc::MovingAverage framedrop_percent_media_opt_

      RTC_GUARDED_BY(&task_checker_);

  rtc::MovingAverage framedrop_percent_all_ RTC_GUARDED_BY(&task_checker_);

  // Used by QualityScalingExperiment.

  const bool experiment_enabled_;

  QualityScalingExperiment::Config config_ RTC_GUARDED_BY(&task_checker_);

  std::unique_ptr<QpSmoother> qp_smoother_high_ RTC_GUARDED_BY(&task_checker_);

  std::unique_ptr<QpSmoother> qp_smoother_low_ RTC_GUARDED_BY(&task_checker_);

  const size_t min_frames_needed_;

  const double initial_scale_factor_;

  const std::optional<double> scale_factor_;

};

// Reacts to QP being too high or too low. For best quality, when QP is high it

// is desired to decrease the resolution or frame rate of the stream and when QP

// is low it is desired to increase the resolution or frame rate of the stream.

// Whether to reconfigure the stream is ultimately up to the handler, which is

// able to respond asynchronously.

class QualityScalerQpUsageHandlerInterface {

 public:

  virtual ~QualityScalerQpUsageHandlerInterface();

  virtual void OnReportQpUsageHigh() = 0;

  virtual void OnReportQpUsageLow() = 0;

};

}  // namespace webrtc

#endif  // MODULES_VIDEO_CODING_UTILITY_QUALITY_SCALER_H_