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| 1 /* |
| 2 * Copyright (c) 2012 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_SYSTEM_WRAPPERS_INCLUDE_RTP_TO_NTP_ESTIMATOR_H_ |
| 12 #define WEBRTC_SYSTEM_WRAPPERS_INCLUDE_RTP_TO_NTP_ESTIMATOR_H_ |
| 13 |
| 14 #include <list> |
| 15 |
| 16 #include "webrtc/system_wrappers/include/ntp_time.h" |
| 17 #include "webrtc/typedefs.h" |
| 18 |
| 19 namespace webrtc { |
| 20 // Class for converting an RTP timestamp to the NTP domain in milliseconds. |
| 21 // The class needs to be trained with (at least 2) RTP/NTP timestamp pairs from |
| 22 // RTCP sender reports before the convertion can be done. |
| 23 class RtpToNtpEstimator { |
| 24 public: |
| 25 RtpToNtpEstimator(); |
| 26 ~RtpToNtpEstimator(); |
| 27 |
| 28 // RTP and NTP timestamp pair from a RTCP SR report. |
| 29 struct RtcpMeasurement { |
| 30 RtcpMeasurement(uint32_t ntp_secs, uint32_t ntp_frac, uint32_t timestamp); |
| 31 bool IsEqual(const RtcpMeasurement& other) const; |
| 32 |
| 33 NtpTime ntp_time; |
| 34 uint32_t rtp_timestamp; |
| 35 }; |
| 36 |
| 37 // Estimated parameters from RTP and NTP timestamp pairs in |measurements_|. |
| 38 struct Parameters { |
| 39 double frequency_khz = 0.0; |
| 40 double offset_ms = 0.0; |
| 41 bool calculated = false; |
| 42 }; |
| 43 |
| 44 // Updates measurements with RTP/NTP timestamp pair from a RTCP sender report. |
| 45 // |new_rtcp_sr| is set to true if a new report is added. |
| 46 bool UpdateMeasurements(uint32_t ntp_secs, |
| 47 uint32_t ntp_frac, |
| 48 uint32_t rtp_timestamp, |
| 49 bool* new_rtcp_sr); |
| 50 |
| 51 // Converts an RTP timestamp to the NTP domain in milliseconds. |
| 52 // Returns true on success, false otherwise. |
| 53 bool Estimate(int64_t rtp_timestamp, int64_t* rtp_timestamp_ms) const; |
| 54 |
| 55 const Parameters& params() const { return params_; } |
| 56 |
| 57 private: |
| 58 void UpdateParameters(); |
| 59 |
| 60 std::list<RtcpMeasurement> measurements_; |
| 61 Parameters params_; |
| 62 }; |
| 63 |
| 64 // Returns: |
| 65 // 1: forward wrap around. |
| 66 // 0: no wrap around. |
| 67 // -1: backwards wrap around (i.e. reordering). |
| 68 int CheckForWrapArounds(uint32_t new_timestamp, uint32_t old_timestamp); |
| 69 |
| 70 } // namespace webrtc |
| 71 |
| 72 #endif // WEBRTC_SYSTEM_WRAPPERS_INCLUDE_RTP_TO_NTP_ESTIMATOR_H_ |
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