1 /* 2 * Copyright (c) 2018 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 #ifndef CALL_RECEIVE_TIME_CALCULATOR_H_ 11 #define CALL_RECEIVE_TIME_CALCULATOR_H_ 12 13 #include <stdint.h> 14 15 #include <memory> 16 17 #include "api/units/time_delta.h" 18 #include "rtc_base/experiments/field_trial_parser.h" 19 20 namespace webrtc { 21 22 struct ReceiveTimeCalculatorConfig { 23 ReceiveTimeCalculatorConfig(); 24 ReceiveTimeCalculatorConfig(const ReceiveTimeCalculatorConfig&); 25 ReceiveTimeCalculatorConfig& operator=(const ReceiveTimeCalculatorConfig&) = 26 default; 27 ~ReceiveTimeCalculatorConfig(); 28 FieldTrialParameter<TimeDelta> max_packet_time_repair; 29 FieldTrialParameter<TimeDelta> stall_threshold; 30 FieldTrialParameter<TimeDelta> tolerance; 31 FieldTrialParameter<TimeDelta> max_stall; 32 }; 33 34 // The receive time calculator serves the purpose of combining packet time 35 // stamps with a safely incremental clock. This assumes that the packet time 36 // stamps are based on lower layer timestamps that have more accurate time 37 // increments since they are based on the exact receive time. They might 38 // however, have large jumps due to clock resets in the system. To compensate 39 // this they are combined with a safe clock source that is guaranteed to be 40 // consistent, but it will not be able to measure the exact time when a packet 41 // is received. 42 class ReceiveTimeCalculator { 43 public: 44 static std::unique_ptr<ReceiveTimeCalculator> CreateFromFieldTrial(); 45 ReceiveTimeCalculator(); 46 int64_t ReconcileReceiveTimes(int64_t packet_time_us_, 47 int64_t system_time_us_, 48 int64_t safe_time_us_); 49 50 private: 51 int64_t last_corrected_time_us_ = -1; 52 int64_t last_packet_time_us_ = -1; 53 int64_t last_system_time_us_ = -1; 54 int64_t last_safe_time_us_ = -1; 55 int64_t total_system_time_passed_us_ = 0; 56 int64_t static_clock_offset_us_ = 0; 57 int64_t small_reset_during_stall_ = false; 58 ReceiveTimeCalculatorConfig config_; 59 }; 60 } // namespace webrtc 61 #endif // CALL_RECEIVE_TIME_CALCULATOR_H_ 62