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| 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. |
| 20 inline 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. |
| 26 inline 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. |
| 38 inline 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). |
| 43 inline 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_ |
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