capture_clock_offset_updater.h (2154B)
1 /* 2 * Copyright (c) 2021 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_SOURCE_CAPTURE_CLOCK_OFFSET_UPDATER_H_ 12 #define MODULES_RTP_RTCP_SOURCE_CAPTURE_CLOCK_OFFSET_UPDATER_H_ 13 14 #include <stdint.h> 15 16 #include <optional> 17 18 #include "api/units/time_delta.h" 19 20 namespace webrtc { 21 22 // 23 // Helper class for calculating the clock offset against the capturer's clock. 24 // 25 // This is achieved by adjusting the estimated capture clock offset in received 26 // Absolute Capture Time RTP header extension (see 27 // https://webrtc.org/experiments/rtp-hdrext/abs-capture-time/), which 28 // represents the clock offset between a remote sender and the capturer, by 29 // adding local-to-remote clock offset. 30 31 class CaptureClockOffsetUpdater { 32 public: 33 // Adjusts remote_capture_clock_offset, which originates from Absolute Capture 34 // Time RTP header extension, to get the local clock offset against the 35 // capturer's clock. 36 std::optional<int64_t> AdjustEstimatedCaptureClockOffset( 37 std::optional<int64_t> remote_capture_clock_offset) const; 38 39 // Sets the NTP clock offset between the sender system (which may be different 40 // from the capture system) and the local system. This information is normally 41 // provided by passing half the value of the Round-Trip Time estimation given 42 // by RTCP sender reports (see DLSR/DLRR). 43 // 44 // Note that the value must be in Q32.32-formatted fixed-point seconds. 45 void SetRemoteToLocalClockOffset(std::optional<int64_t> offset_q32x32); 46 47 // Converts a signed Q32.32-formatted fixed-point to a TimeDelta. 48 static std::optional<TimeDelta> ConvertToTimeDelta( 49 std::optional<int64_t> q32x32); 50 51 private: 52 std::optional<int64_t> remote_to_local_clock_offset_; 53 }; 54 55 } // namespace webrtc 56 57 #endif // MODULES_RTP_RTCP_SOURCE_CAPTURE_CLOCK_OFFSET_UPDATER_H_