Line data    Source code

       1             : /*
       2             :  *  Copyright (c) 2014 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             : #include "webrtc/modules/rtp_rtcp/include/remote_ntp_time_estimator.h"
      12             : 
      13             : #include "webrtc/base/logging.h"
      14             : #include "webrtc/system_wrappers/include/clock.h"
      15             : #include "webrtc/system_wrappers/include/timestamp_extrapolator.h"
      16             : 
      17             : namespace webrtc {
      18             : 
      19             : static const int kTimingLogIntervalMs = 10000;
      20             : 
      21             : // TODO(wu): Refactor this class so that it can be shared with
      22             : // vie_sync_module.cc.
      23           0 : RemoteNtpTimeEstimator::RemoteNtpTimeEstimator(Clock* clock)
      24             :     : clock_(clock),
      25           0 :       ts_extrapolator_(new TimestampExtrapolator(clock_->TimeInMilliseconds())),
      26           0 :       last_timing_log_ms_(-1) {
      27           0 : }
      28             : 
      29           0 : RemoteNtpTimeEstimator::~RemoteNtpTimeEstimator() {}
      30             : 
      31           0 : bool RemoteNtpTimeEstimator::UpdateRtcpTimestamp(int64_t rtt,
      32             :                                                  uint32_t ntp_secs,
      33             :                                                  uint32_t ntp_frac,
      34             :                                                  uint32_t rtcp_timestamp) {
      35           0 :   bool new_rtcp_sr = false;
      36           0 :   if (!rtp_to_ntp_.UpdateMeasurements(ntp_secs, ntp_frac, rtcp_timestamp,
      37             :                                       &new_rtcp_sr)) {
      38           0 :     return false;
      39             :   }
      40           0 :   if (!new_rtcp_sr) {
      41             :     // No new RTCP SR since last time this function was called.
      42           0 :     return true;
      43             :   }
      44             :   // Update extrapolator with the new arrival time.
      45             :   // The extrapolator assumes the TimeInMilliseconds time.
      46           0 :   int64_t receiver_arrival_time_ms = clock_->TimeInMilliseconds();
      47           0 :   int64_t sender_send_time_ms = Clock::NtpToMs(ntp_secs, ntp_frac);
      48           0 :   int64_t sender_arrival_time_90k = (sender_send_time_ms + rtt / 2) * 90;
      49           0 :   ts_extrapolator_->Update(receiver_arrival_time_ms, sender_arrival_time_90k);
      50           0 :   return true;
      51             : }
      52             : 
      53           0 : int64_t RemoteNtpTimeEstimator::Estimate(uint32_t rtp_timestamp) {
      54           0 :   int64_t sender_capture_ntp_ms = 0;
      55           0 :   if (!rtp_to_ntp_.Estimate(rtp_timestamp, &sender_capture_ntp_ms)) {
      56           0 :     return -1;
      57             :   }
      58           0 :   uint32_t timestamp = sender_capture_ntp_ms * 90;
      59             :   int64_t receiver_capture_ms =
      60           0 :       ts_extrapolator_->ExtrapolateLocalTime(timestamp);
      61             :   int64_t ntp_offset =
      62           0 :       clock_->CurrentNtpInMilliseconds() - clock_->TimeInMilliseconds();
      63           0 :   int64_t receiver_capture_ntp_ms = receiver_capture_ms + ntp_offset;
      64           0 :   int64_t now_ms = clock_->TimeInMilliseconds();
      65           0 :   if (now_ms - last_timing_log_ms_ > kTimingLogIntervalMs) {
      66           0 :     LOG(LS_INFO) << "RTP timestamp: " << rtp_timestamp
      67           0 :                  << " in NTP clock: " << sender_capture_ntp_ms
      68           0 :                  << " estimated time in receiver clock: " << receiver_capture_ms
      69           0 :                  << " converted to NTP clock: " << receiver_capture_ntp_ms;
      70           0 :     last_timing_log_ms_ = now_ms;
      71             :   }
      72           0 :   return receiver_capture_ntp_ms;
      73             : }
      74             : 
      75             : }  // namespace webrtc