1 /* 2 * Copyright (c) 2011 The WebRTC project authors. All Rights Reserved. 3 * 4 * Use of this source code is governed by a BSD-style license 5 * that can be found in the LICENSE file in the root of the source 6 * tree. An additional intellectual property rights grant can be found 7 * in the file PATENTS. All contributing project authors may 8 * be found in the AUTHORS file in the root of the source tree. 9 */ 10 11 #ifndef WEBRTC_MODULES_VIDEO_CODING_UTILITY_FRAME_DROPPER_H_ 12 #define WEBRTC_MODULES_VIDEO_CODING_UTILITY_FRAME_DROPPER_H_ 13 14 #include <cstddef> 15 16 #include "webrtc/base/exp_filter.h" 17 #include "webrtc/typedefs.h" 18 19 namespace webrtc { 20 21 // The Frame Dropper implements a variant of the leaky bucket algorithm 22 // for keeping track of when to drop frames to avoid bit rate 23 // over use when the encoder can't keep its bit rate. 24 class FrameDropper { 25 public: 26 FrameDropper(); 27 explicit FrameDropper(float max_time_drops); ~FrameDropper()28 virtual ~FrameDropper() {} 29 30 // Resets the FrameDropper to its initial state. 31 // This means that the frameRateWeight is set to its 32 // default value as well. 33 virtual void Reset(); 34 35 virtual void Enable(bool enable); 36 // Answers the question if it's time to drop a frame 37 // if we want to reach a given frame rate. Must be 38 // called for every frame. 39 // 40 // Return value : True if we should drop the current frame 41 virtual bool DropFrame(); 42 // Updates the FrameDropper with the size of the latest encoded 43 // frame. The FrameDropper calculates a new drop ratio (can be 44 // seen as the probability to drop a frame) and updates its 45 // internal statistics. 46 // 47 // Input: 48 // - frameSizeBytes : The size of the latest frame 49 // returned from the encoder. 50 // - deltaFrame : True if the encoder returned 51 // a key frame. 52 virtual void Fill(size_t frameSizeBytes, bool deltaFrame); 53 54 virtual void Leak(uint32_t inputFrameRate); 55 56 void UpdateNack(uint32_t nackBytes); 57 58 // Sets the target bit rate and the frame rate produced by 59 // the camera. 60 // 61 // Input: 62 // - bitRate : The target bit rate 63 virtual void SetRates(float bitRate, float incoming_frame_rate); 64 65 // Return value : The current average frame rate produced 66 // if the DropFrame() function is used as 67 // instruction of when to drop frames. 68 virtual float ActualFrameRate(uint32_t inputFrameRate) const; 69 70 private: 71 void FillBucket(float inKbits, float outKbits); 72 void UpdateRatio(); 73 void CapAccumulator(); 74 75 rtc::ExpFilter _keyFrameSizeAvgKbits; 76 rtc::ExpFilter _keyFrameRatio; 77 float _keyFrameSpreadFrames; 78 int32_t _keyFrameCount; 79 float _accumulator; 80 float _accumulatorMax; 81 float _targetBitRate; 82 bool _dropNext; 83 rtc::ExpFilter _dropRatio; 84 int32_t _dropCount; 85 float _windowSize; 86 float _incoming_frame_rate; 87 bool _wasBelowMax; 88 bool _enabled; 89 bool _fastMode; 90 float _cap_buffer_size; 91 float _max_time_drops; 92 }; // end of VCMFrameDropper class 93 94 } // namespace webrtc 95 96 #endif // WEBRTC_MODULES_VIDEO_CODING_UTILITY_FRAME_DROPPER_H_ 97