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
17namespace webrtc {
18
19// Converts NTP timestamp to RTP timestamp.
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.
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.
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).
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