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f987c78d14
Bug: b/232293787 Change-Id: I7f781ff38a23ae829447e5274ec7f6493de8195d Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/262240 Commit-Queue: Danil Chapovalov <danilchap@webrtc.org> Reviewed-by: Emil Lundmark <lndmrk@webrtc.org> Cr-Commit-Position: refs/heads/main@{#36863}
56 lines
2.2 KiB
C++
56 lines
2.2 KiB
C++
/*
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* Copyright (c) 2015 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 MODULES_RTP_RTCP_SOURCE_TIME_UTIL_H_
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#define MODULES_RTP_RTCP_SOURCE_TIME_UTIL_H_
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#include <stdint.h>
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#include "api/units/time_delta.h"
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#include "rtc_base/numerics/safe_conversions.h"
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#include "system_wrappers/include/ntp_time.h"
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namespace webrtc {
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// Helper function for compact ntp representation:
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// RFC 3550, Section 4. Time Format.
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// Wallclock time is represented using the timestamp format of
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// the Network Time Protocol (NTP).
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// ...
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// In some fields where a more compact representation is
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// appropriate, only the middle 32 bits are used; that is, the low 16
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// bits of the integer part and the high 16 bits of the fractional part.
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inline uint32_t CompactNtp(NtpTime ntp) {
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return (ntp.seconds() << 16) | (ntp.fractions() >> 16);
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}
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// Converts interval to compact ntp (1/2^16 seconds) resolution.
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// Negative values converted to 0, Overlarge values converted to max uint32_t.
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uint32_t SaturatedToCompactNtp(TimeDelta delta);
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// Convert interval to the NTP time resolution (1/2^32 seconds ~= 0.2 ns).
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// For deltas with absolute value larger than 35 minutes result is unspecified.
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inline constexpr int64_t ToNtpUnits(TimeDelta delta) {
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// For better precision `delta` is taken with best TimeDelta precision (us),
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// then multiplaction and conversion to seconds are swapped to avoid float
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// arithmetic.
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// 2^31 us ~= 35.8 minutes.
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return (rtc::saturated_cast<int32_t>(delta.us()) * (int64_t{1} << 32)) /
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1'000'000;
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}
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// Converts interval from compact ntp (1/2^16 seconds) resolution to TimeDelta.
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// This interval can be up to ~9.1 hours (2^15 seconds).
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// Values close to 2^16 seconds are considered negative and are converted to
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// minimum value of 1ms.
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TimeDelta CompactNtpRttToTimeDelta(uint32_t compact_ntp_interval);
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} // namespace webrtc
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#endif // MODULES_RTP_RTCP_SOURCE_TIME_UTIL_H_
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