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_JITTER_ESTIMATOR_H_ 12 #define WEBRTC_MODULES_VIDEO_CODING_JITTER_ESTIMATOR_H_ 13 14 #include "webrtc/base/rollingaccumulator.h" 15 #include "webrtc/modules/video_coding/main/source/rtt_filter.h" 16 #include "webrtc/typedefs.h" 17 18 namespace webrtc 19 { 20 21 class Clock; 22 23 class VCMJitterEstimator 24 { 25 public: 26 VCMJitterEstimator(const Clock* clock, 27 int32_t vcmId = 0, 28 int32_t receiverId = 0); 29 virtual ~VCMJitterEstimator(); 30 VCMJitterEstimator& operator=(const VCMJitterEstimator& rhs); 31 32 // Resets the estimate to the initial state 33 void Reset(); 34 void ResetNackCount(); 35 36 // Updates the jitter estimate with the new data. 37 // 38 // Input: 39 // - frameDelay : Delay-delta calculated by UTILDelayEstimate in milliseconds 40 // - frameSize : Frame size of the current frame. 41 // - incompleteFrame : Flags if the frame is used to update the estimate before it 42 // was complete. Default is false. 43 void UpdateEstimate(int64_t frameDelayMS, 44 uint32_t frameSizeBytes, 45 bool incompleteFrame = false); 46 47 // Returns the current jitter estimate in milliseconds and adds 48 // also adds an RTT dependent term in cases of retransmission. 49 // Input: 50 // - rttMultiplier : RTT param multiplier (when applicable). 51 // 52 // Return value : Jitter estimate in milliseconds 53 int GetJitterEstimate(double rttMultiplier); 54 55 // Updates the nack counter. 56 void FrameNacked(); 57 58 // Updates the RTT filter. 59 // 60 // Input: 61 // - rttMs : RTT in ms 62 void UpdateRtt(uint32_t rttMs); 63 64 void UpdateMaxFrameSize(uint32_t frameSizeBytes); 65 66 // A constant describing the delay from the jitter buffer 67 // to the delay on the receiving side which is not accounted 68 // for by the jitter buffer nor the decoding delay estimate. 69 static const uint32_t OPERATING_SYSTEM_JITTER = 10; 70 71 protected: 72 // These are protected for better testing possibilities 73 double _theta[2]; // Estimated line parameters (slope, offset) 74 double _varNoise; // Variance of the time-deviation from the line 75 76 virtual bool LowRateExperimentEnabled(); 77 78 private: 79 // Updates the Kalman filter for the line describing 80 // the frame size dependent jitter. 81 // 82 // Input: 83 // - frameDelayMS : Delay-delta calculated by UTILDelayEstimate in milliseconds 84 // - deltaFSBytes : Frame size delta, i.e. 85 // : frame size at time T minus frame size at time T-1 86 void KalmanEstimateChannel(int64_t frameDelayMS, int32_t deltaFSBytes); 87 88 // Updates the random jitter estimate, i.e. the variance 89 // of the time deviations from the line given by the Kalman filter. 90 // 91 // Input: 92 // - d_dT : The deviation from the kalman estimate 93 // - incompleteFrame : True if the frame used to update the estimate 94 // with was incomplete 95 void EstimateRandomJitter(double d_dT, bool incompleteFrame); 96 97 double NoiseThreshold() const; 98 99 // Calculates the current jitter estimate. 100 // 101 // Return value : The current jitter estimate in milliseconds 102 double CalculateEstimate(); 103 104 // Post process the calculated estimate 105 void PostProcessEstimate(); 106 107 // Calculates the difference in delay between a sample and the 108 // expected delay estimated by the Kalman filter. 109 // 110 // Input: 111 // - frameDelayMS : Delay-delta calculated by UTILDelayEstimate in milliseconds 112 // - deltaFS : Frame size delta, i.e. frame size at time 113 // T minus frame size at time T-1 114 // 115 // Return value : The difference in milliseconds 116 double DeviationFromExpectedDelay(int64_t frameDelayMS, 117 int32_t deltaFSBytes) const; 118 119 double GetFrameRate() const; 120 121 // Constants, filter parameters 122 int32_t _vcmId; 123 int32_t _receiverId; 124 const double _phi; 125 const double _psi; 126 const uint32_t _alphaCountMax; 127 const double _thetaLow; 128 const uint32_t _nackLimit; 129 const int32_t _numStdDevDelayOutlier; 130 const int32_t _numStdDevFrameSizeOutlier; 131 const double _noiseStdDevs; 132 const double _noiseStdDevOffset; 133 134 double _thetaCov[2][2]; // Estimate covariance 135 double _Qcov[2][2]; // Process noise covariance 136 double _avgFrameSize; // Average frame size 137 double _varFrameSize; // Frame size variance 138 double _maxFrameSize; // Largest frame size received (descending 139 // with a factor _psi) 140 uint32_t _fsSum; 141 uint32_t _fsCount; 142 143 int64_t _lastUpdateT; 144 double _prevEstimate; // The previously returned jitter estimate 145 uint32_t _prevFrameSize; // Frame size of the previous frame 146 double _avgNoise; // Average of the random jitter 147 uint32_t _alphaCount; 148 double _filterJitterEstimate; // The filtered sum of jitter estimates 149 150 uint32_t _startupCount; 151 152 int64_t _latestNackTimestamp; // Timestamp in ms when the latest nack was seen 153 uint32_t _nackCount; // Keeps track of the number of nacks received, 154 // but never goes above _nackLimit 155 VCMRttFilter _rttFilter; 156 157 rtc::RollingAccumulator<uint64_t> fps_counter_; 158 enum ExperimentFlag { kInit, kEnabled, kDisabled }; 159 ExperimentFlag low_rate_experiment_; 160 const Clock* clock_; 161 }; 162 163 } // namespace webrtc 164 165 #endif // WEBRTC_MODULES_VIDEO_CODING_JITTER_ESTIMATOR_H_ 166
