1 /*
2  *  Copyright (c) 2014 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 MODULES_RTP_RTCP_INCLUDE_REMOTE_NTP_TIME_ESTIMATOR_H_
12 #define MODULES_RTP_RTCP_INCLUDE_REMOTE_NTP_TIME_ESTIMATOR_H_
13 
14 #include <memory>
15 
16 #include "rtc_base/constructormagic.h"
17 #include "rtc_base/numerics/moving_median_filter.h"
18 #include "system_wrappers/include/rtp_to_ntp_estimator.h"
19 
20 namespace webrtc {
21 
22 class Clock;
23 
24 // RemoteNtpTimeEstimator can be used to estimate a given RTP timestamp's NTP
25 // time in local timebase.
26 // Note that it needs to be trained with at least 2 RTCP SR (by calling
27 // |UpdateRtcpTimestamp|) before it can be used.
28 class RemoteNtpTimeEstimator {
29  public:
30   explicit RemoteNtpTimeEstimator(Clock* clock);
31 
32   ~RemoteNtpTimeEstimator();
33 
34   // Updates the estimator with round trip time |rtt|, NTP seconds |ntp_secs|,
35   // NTP fraction |ntp_frac| and RTP timestamp |rtcp_timestamp|.
36   bool UpdateRtcpTimestamp(int64_t rtt, uint32_t ntp_secs, uint32_t ntp_frac,
37                            uint32_t rtp_timestamp);
38 
39   // Estimates the NTP timestamp in local timebase from |rtp_timestamp|.
40   // Returns the NTP timestamp in ms when success. -1 if failed.
41   int64_t Estimate(uint32_t rtp_timestamp);
42 
43  private:
44   Clock* clock_;
45   MovingMedianFilter<int64_t> ntp_clocks_offset_estimator_;
46   RtpToNtpEstimator rtp_to_ntp_;
47   int64_t last_timing_log_ms_;
48   RTC_DISALLOW_COPY_AND_ASSIGN(RemoteNtpTimeEstimator);
49 };
50 
51 }  // namespace webrtc
52 
53 #endif  // MODULES_RTP_RTCP_INCLUDE_REMOTE_NTP_TIME_ESTIMATOR_H_
54