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/*
* Copyright (c) 2011 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_MODULES_VIDEO_CODING_UTILITY_FRAME_DROPPER_H_
#define WEBRTC_MODULES_VIDEO_CODING_UTILITY_FRAME_DROPPER_H_
#include <cstddef>
#include "webrtc/base/exp_filter.h"
#include "webrtc/typedefs.h"
namespace webrtc {
// The Frame Dropper implements a variant of the leaky bucket algorithm
// for keeping track of when to drop frames to avoid bit rate
// over use when the encoder can't keep its bit rate.
class FrameDropper {
public:
FrameDropper();
explicit FrameDropper(float max_time_drops);
virtual ~FrameDropper() {}
// Resets the FrameDropper to its initial state.
// This means that the frameRateWeight is set to its
// default value as well.
virtual void Reset();
virtual void Enable(bool enable);
// Answers the question if it's time to drop a frame
// if we want to reach a given frame rate. Must be
// called for every frame.
//
// Return value : True if we should drop the current frame
virtual bool DropFrame();
// Updates the FrameDropper with the size of the latest encoded
// frame. The FrameDropper calculates a new drop ratio (can be
// seen as the probability to drop a frame) and updates its
// internal statistics.
//
// Input:
// - frameSizeBytes : The size of the latest frame
// returned from the encoder.
// - deltaFrame : True if the encoder returned
// a key frame.
virtual void Fill(size_t frameSizeBytes, bool deltaFrame);
virtual void Leak(uint32_t inputFrameRate);
void UpdateNack(uint32_t nackBytes);
// Sets the target bit rate and the frame rate produced by
// the camera.
//
// Input:
// - bitRate : The target bit rate
virtual void SetRates(float bitRate, float incoming_frame_rate);
// Return value : The current average frame rate produced
// if the DropFrame() function is used as
// instruction of when to drop frames.
virtual float ActualFrameRate(uint32_t inputFrameRate) const;
private:
void FillBucket(float inKbits, float outKbits);
void UpdateRatio();
void CapAccumulator();
rtc::ExpFilter _keyFrameSizeAvgKbits;
rtc::ExpFilter _keyFrameRatio;
float _keyFrameSpreadFrames;
int32_t _keyFrameCount;
float _accumulator;
float _accumulatorMax;
float _targetBitRate;
bool _dropNext;
rtc::ExpFilter _dropRatio;
int32_t _dropCount;
float _windowSize;
float _incoming_frame_rate;
bool _wasBelowMax;
bool _enabled;
bool _fastMode;
float _cap_buffer_size;
float _max_time_drops;
}; // end of VCMFrameDropper class
} // namespace webrtc
#endif // WEBRTC_MODULES_VIDEO_CODING_UTILITY_FRAME_DROPPER_H_
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