webrtc/video_engine/overuse_frame_detector.h

/*
 *  Copyright (c) 2013 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 WEBRTC_VIDEO_ENGINE_OVERUSE_FRAME_DETECTOR_H_
#define WEBRTC_VIDEO_ENGINE_OVERUSE_FRAME_DETECTOR_H_

#include "webrtc/modules/interface/module.h"
#include "webrtc/system_wrappers/interface/constructor_magic.h"
#include "webrtc/system_wrappers/interface/scoped_ptr.h"

namespace webrtc {

class Clock;
class CriticalSectionWrapper;
class CpuOveruseObserver;

// TODO(pbos): Move this somewhere appropriate
class Statistics {
 public:
  Statistics();

  void AddSample(double sample);
  void Reset();

  double Mean() const;
  double Variance() const;
  double StdDev() const;
  uint64_t Samples() const;

 private:
  double sum_;
  double sum_squared_;
  uint64_t count_;
};

// Use to detect system overuse based on jitter in incoming frames.
class OveruseFrameDetector : public Module {
 public:
  explicit OveruseFrameDetector(Clock* clock);
  ~OveruseFrameDetector();

  // Registers an observer receiving overuse and underuse callbacks. Set
  // 'observer' to NULL to disable callbacks.
  void SetObserver(CpuOveruseObserver* observer);

  // Called for each captured frame.
  void FrameCaptured();

  // Implements Module.
  virtual int32_t TimeUntilNextProcess() OVERRIDE;
  virtual int32_t Process() OVERRIDE;

 private:
  bool IsOverusing();
  bool IsUnderusing(int64_t time_now);

  // Protecting all members.
  scoped_ptr<CriticalSectionWrapper> crit_;

  // Observer getting overuse reports.
  CpuOveruseObserver* observer_;

  Clock* clock_;
  int64_t next_process_time_;

  Statistics capture_deltas_;
  int64_t last_capture_time_;

  int64_t last_overuse_time_;
  int checks_above_threshold_;

  int64_t last_rampup_time_;
  bool in_quick_rampup_;
  int current_rampup_delay_ms_;

  DISALLOW_COPY_AND_ASSIGN(OveruseFrameDetector);
};

}  // namespace webrtc

#endif  // WEBRTC_VIDEO_ENGINE_OVERUSE_FRAME_DETECTOR_H_