b34556e598
The receive time calculator combines the packet time stamps received from the socket interface with the system clock used in WebRTC. This means that the packet timestamps are set in the WebRTC clock timebase and that large jumps in the time stamps from the socket will not affect the reported receive time stamps. Bug: None Change-Id: I293925c41919829524a115bb9377027bf0a797fb Reviewed-on: https://webrtc-review.googlesource.com/61862 Reviewed-by: Niels Moller <nisse@webrtc.org> Reviewed-by: Christoffer Rodbro <crodbro@webrtc.org> Commit-Queue: Sebastian Jansson <srte@webrtc.org> Cr-Commit-Position: refs/heads/master@{#22540}
48 lines
2.0 KiB
C++
48 lines
2.0 KiB
C++
/*
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* Copyright (c) 2018 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#ifndef CALL_RECEIVE_TIME_CALCULATOR_H_
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#define CALL_RECEIVE_TIME_CALCULATOR_H_
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#include <stdint.h>
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#include <memory>
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#include "api/optional.h"
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namespace webrtc {
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// The receive time calculator serves the purpose of combining packet time
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// stamps with a safely incremental clock. This assumes that the packet time
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// stamps are based on lower layer timestamps that have more accurate time
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// increments since they are based on the exact receive time. They might
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// however, have large jumps due to clock resets in the system. To compensate
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// this they are combined with a safe clock source that is guaranteed to be
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// consistent, but it will not be able to measure the exact time when a packet
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// is received.
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class ReceiveTimeCalculator {
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public:
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static std::unique_ptr<ReceiveTimeCalculator> CreateFromFieldTrial();
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// The min delta is used to correct for jumps backwards in time, to allow some
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// packet reordering a small negative value is appropriate to use. The max
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// delta difference is used as margin when detecting when packet time
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// increases more than the safe clock. This should be larger than the largest
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// expected sysmtem induced delay in the safe clock timestamp.
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ReceiveTimeCalculator(int64_t min_delta_ms, int64_t max_delta_diff_ms);
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int64_t ReconcileReceiveTimes(int64_t packet_time_us_, int64_t safe_time_us_);
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private:
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const int64_t min_delta_us_;
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const int64_t max_delta_diff_us_;
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rtc::Optional<int64_t> receive_time_offset_us_;
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int64_t last_packet_time_us_ = 0;
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int64_t last_safe_time_us_ = 0;
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};
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} // namespace webrtc
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#endif // CALL_RECEIVE_TIME_CALCULATOR_H_
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