Line data    Source code

       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 <stdint.h>
      15             : 
      16             : #include "webrtc/system_wrappers/include/ntp_time.h"
      17             : 
      18             : namespace webrtc {
      19             : 
      20             : // Converts NTP timestamp to RTP timestamp.
      21           0 : inline uint32_t NtpToRtp(NtpTime ntp, uint32_t freq) {
      22           0 :   uint32_t tmp = (static_cast<uint64_t>(ntp.fractions()) * freq) >> 32;
      23           0 :   return ntp.seconds() * freq + tmp;
      24             : }
      25             : // Return the current RTP timestamp from the NTP timestamp
      26             : // returned by the specified clock.
      27             : inline uint32_t CurrentRtp(const Clock& clock, uint32_t freq) {
      28             :   return NtpToRtp(NtpTime(clock), freq);
      29             : }
      30             : 
      31             : // Helper function for compact ntp representation:
      32             : // RFC 3550, Section 4. Time Format.
      33             : // Wallclock time is represented using the timestamp format of
      34             : // the Network Time Protocol (NTP).
      35             : // ...
      36             : // In some fields where a more compact representation is
      37             : // appropriate, only the middle 32 bits are used; that is, the low 16
      38             : // bits of the integer part and the high 16 bits of the fractional part.
      39           0 : inline uint32_t CompactNtp(NtpTime ntp) {
      40           0 :   return (ntp.seconds() << 16) | (ntp.fractions() >> 16);
      41             : }
      42             : // Converts interval between compact ntp timestamps to milliseconds.
      43             : // This interval can be up to ~9.1 hours (2^15 seconds).
      44             : // Values close to 2^16 seconds consider negative and result in minimum rtt = 1.
      45             : int64_t CompactNtpRttToMs(uint32_t compact_ntp_interval);
      46             : 
      47             : }  // namespace webrtc
      48             : #endif  // WEBRTC_MODULES_RTP_RTCP_SOURCE_TIME_UTIL_H_