639494be57
Similar to CompactNtpRttToTimeDelta but can return negative values. Bug: webrtc:42225697 Change-Id: Iea97502ea73eb6240f42c2040cdc576e51298704 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/366422 Reviewed-by: Danil Chapovalov <danilchap@webrtc.org> Commit-Queue: Per Kjellander <perkj@webrtc.org> Cr-Commit-Position: refs/heads/main@{#43284}
61 lines
2.5 KiB
C++
61 lines
2.5 KiB
C++
/*
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* Copyright (c) 2016 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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#include "modules/rtp_rtcp/source/ntp_time_util.h"
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#include <algorithm>
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#include <cstdint>
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#include "api/units/time_delta.h"
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#include "rtc_base/numerics/divide_round.h"
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#include "rtc_base/time_utils.h"
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namespace webrtc {
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uint32_t SaturatedToCompactNtp(TimeDelta delta) {
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constexpr uint32_t kMaxCompactNtp = 0xFFFFFFFF;
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constexpr int kCompactNtpInSecond = 0x10000;
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if (delta <= TimeDelta::Zero())
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return 0;
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if (delta.us() >=
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kMaxCompactNtp * rtc::kNumMicrosecsPerSec / kCompactNtpInSecond)
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return kMaxCompactNtp;
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// To convert to compact ntp need to divide by 1e6 to get seconds,
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// then multiply by 0x10000 to get the final result.
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// To avoid float operations, multiplication and division swapped.
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return DivideRoundToNearest(delta.us() * kCompactNtpInSecond,
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rtc::kNumMicrosecsPerSec);
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}
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TimeDelta CompactNtpIntervalToTimeDelta(uint32_t compact_ntp_interval) {
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// Convert to 64bit value to avoid multiplication overflow.
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int64_t value = int64_t{compact_ntp_interval};
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if (compact_ntp_interval > 0x8000'0000) {
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value -= (int64_t{1} << 32);
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}
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// To convert to TimeDelta need to divide by 2^16 to get seconds,
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// then multiply by 1'000'000 to get microseconds. To avoid float operations,
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// multiplication and division are swapped.
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int64_t us = DivideRoundToNearest(value * rtc::kNumMicrosecsPerSec, 1 << 16);
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return TimeDelta::Micros(us);
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}
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TimeDelta CompactNtpRttToTimeDelta(uint32_t compact_ntp_interval) {
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static constexpr TimeDelta kMinRtt = TimeDelta::Millis(1);
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// Interval to convert expected to be positive, e.g. RTT or delay.
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// Because interval can be derived from non-monotonic ntp clock,
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// it might become negative that is indistinguishable from very large values.
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// Since very large RTT/delay is less likely than non-monotonic ntp clock,
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// such value is considered negative and converted to minimum value of 1ms.
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// Small RTT value is considered too good to be true and increased to 1ms.
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return std::max(CompactNtpIntervalToTimeDelta(compact_ntp_interval), kMinRtt);
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}
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} // namespace webrtc
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