/* * Copyright (c) 2015 The WebRTC project authors. All Rights Reserved. * * Use of this source code is governed by a BSD-style license * that can be found in the LICENSE file in the root of the source * tree. An additional intellectual property rights grant can be found * in the file PATENTS. All contributing project authors may * be found in the AUTHORS file in the root of the source tree. */ #ifndef MODULES_RTP_RTCP_SOURCE_NTP_TIME_UTIL_H_ #define MODULES_RTP_RTCP_SOURCE_NTP_TIME_UTIL_H_ #include <stdint.h> #include "api/units/time_delta.h" #include "rtc_base/numerics/safe_conversions.h" #include "system_wrappers/include/ntp_time.h" namespace webrtc { // Helper function for compact ntp representation: // RFC 3550, Section 4. Time Format. // Wallclock time is represented using the timestamp format of // the Network Time Protocol (NTP). // ... // In some fields where a more compact representation is // appropriate, only the middle 32 bits are used; that is, the low 16 // bits of the integer part and the high 16 bits of the fractional part. inline uint32_t CompactNtp(NtpTime ntp) { … } // Converts interval to compact ntp (1/2^16 seconds) resolution. // Negative values converted to 0, Overlarge values converted to max uint32_t. uint32_t SaturatedToCompactNtp(TimeDelta delta); // Convert interval to the NTP time resolution (1/2^32 seconds ~= 0.2 ns). // For deltas with absolute value larger than 35 minutes result is unspecified. inline constexpr int64_t ToNtpUnits(TimeDelta delta) { … } // Converts interval from compact ntp (1/2^16 seconds) resolution to TimeDelta. // This interval can be up to ~9.1 hours (2^15 seconds). // Values close to 2^16 seconds are considered negative and are converted to // minimum value of 1ms. TimeDelta CompactNtpRttToTimeDelta(uint32_t compact_ntp_interval); } // namespace webrtc #endif // MODULES_RTP_RTCP_SOURCE_NTP_TIME_UTIL_H_