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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 MODULES_VIDEO_CODING_UTILITY_FRAME_DROPPER_H_
#define MODULES_VIDEO_CODING_UTILITY_FRAME_DROPPER_H_
#include <cstddef>
#include "rtc_base/numerics/exp_filter.h"
#include "typedefs.h" // NOLINT(build/include)
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);
// 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);
private:
void UpdateRatio();
void CapAccumulator();
rtc::ExpFilter key_frame_ratio_;
rtc::ExpFilter delta_frame_size_avg_kbits_;
// Key frames and large delta frames are not immediately accumulated in the
// bucket since they can immediately overflow the bucket leading to large
// drops on the following packets that may be much smaller. Instead these
// large frames are accumulated over several frames when the bucket leaks.
// |large_frame_accumulation_spread_| represents the number of frames over
// which a large frame is accumulated.
float large_frame_accumulation_spread_;
// |large_frame_accumulation_count_| represents the number of frames left
// to finish accumulating a large frame.
int large_frame_accumulation_count_;
// |large_frame_accumulation_chunk_size_| represents the size of a single
// chunk for large frame accumulation.
float large_frame_accumulation_chunk_size_;
float accumulator_;
float accumulator_max_;
float target_bitrate_;
bool drop_next_;
rtc::ExpFilter drop_ratio_;
int drop_count_;
float incoming_frame_rate_;
bool was_below_max_;
bool enabled_;
const float max_drop_duration_secs_;
};
} // namespace webrtc
#endif // MODULES_VIDEO_CODING_UTILITY_FRAME_DROPPER_H_