1 /* 2 * Copyright (c) 2015 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 WEBRTC_MODULES_RTP_RTCP_SOURCE_TIME_UTIL_H_ 12 #define WEBRTC_MODULES_RTP_RTCP_SOURCE_TIME_UTIL_H_ 13 14 #include "webrtc/base/basictypes.h" 15 #include "webrtc/system_wrappers/include/ntp_time.h" 16 17 namespace webrtc { 18 19 // Converts NTP timestamp to RTP timestamp. NtpToRtp(NtpTime ntp,uint32_t freq)20inline uint32_t NtpToRtp(NtpTime ntp, uint32_t freq) { 21 uint32_t tmp = (static_cast<uint64_t>(ntp.fractions()) * freq) >> 32; 22 return ntp.seconds() * freq + tmp; 23 } 24 // Return the current RTP timestamp from the NTP timestamp 25 // returned by the specified clock. CurrentRtp(const Clock & clock,uint32_t freq)26inline uint32_t CurrentRtp(const Clock& clock, uint32_t freq) { 27 return NtpToRtp(NtpTime(clock), freq); 28 } 29 30 // Helper function for compact ntp representation: 31 // RFC 3550, Section 4. Time Format. 32 // Wallclock time is represented using the timestamp format of 33 // the Network Time Protocol (NTP). 34 // ... 35 // In some fields where a more compact representation is 36 // appropriate, only the middle 32 bits are used; that is, the low 16 37 // bits of the integer part and the high 16 bits of the fractional part. CompactNtp(NtpTime ntp)38inline uint32_t CompactNtp(NtpTime ntp) { 39 return (ntp.seconds() << 16) | (ntp.fractions() >> 16); 40 } 41 // Converts interval between compact ntp timestamps to milliseconds. 42 // This interval can be upto ~18.2 hours (2^16 seconds). CompactNtpIntervalToMs(uint32_t compact_ntp_interval)43inline uint32_t CompactNtpIntervalToMs(uint32_t compact_ntp_interval) { 44 return static_cast<uint64_t>(compact_ntp_interval) * 1000 / (1 << 16); 45 } 46 47 } // namespace webrtc 48 #endif // WEBRTC_MODULES_RTP_RTCP_SOURCE_TIME_UTIL_H_ 49