src/media/cast/logging/receiver_time_offset_estimator_impl.cc

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include <algorithm>
   6 #include <utility>
   7
   8 #include "base/logging.h"
   9 #include "base/time/tick_clock.h"
  10 #include "media/cast/logging/receiver_time_offset_estimator_impl.h"
  11
  12 namespace media {
  13 namespace cast {
  14
  15 ReceiverTimeOffsetEstimatorImpl::BoundCalculator::BoundCalculator()
  16     : has_bound_(false) {}
  17 ReceiverTimeOffsetEstimatorImpl::BoundCalculator::~BoundCalculator() {}
  18
  19 void ReceiverTimeOffsetEstimatorImpl::BoundCalculator::SetSent(
  20     uint32 rtp,
  21     uint32 packet_id,
  22     bool audio,
  23     base::TimeTicks t) {
  24   uint64 key = (static_cast<uint64>(rtp) << 32) | (packet_id << 1) |
  25       static_cast<uint64>(audio);
  26   events_[key].first = t;
  27   CheckUpdate(key);
  28 }
  29
  30 void ReceiverTimeOffsetEstimatorImpl::BoundCalculator::SetReceived(
  31     uint32 rtp,
  32     uint16 packet_id,
  33     bool audio,
  34     base::TimeTicks t) {
  35   uint64 key = (static_cast<uint64>(rtp) << 32) | (packet_id << 1) |
  36       static_cast<uint64>(audio);
  37   events_[key].second = t;
  38   CheckUpdate(key);
  39 }
  40
  41 void ReceiverTimeOffsetEstimatorImpl::BoundCalculator::UpdateBound(
  42     base::TimeTicks sent, base::TimeTicks received) {
  43     base::TimeDelta delta = received - sent;
  44     if (has_bound_) {
  45       if (delta < bound_) {
  46         bound_ = delta;
  47       } else {
  48         bound_ += (delta - bound_) / kClockDriftSpeed;
  49       }
  50     } else {
  51       bound_ = delta;
  52     }
  53     has_bound_ = true;
  54   }
  55
  56 void ReceiverTimeOffsetEstimatorImpl::BoundCalculator::CheckUpdate(
  57     uint64 key) {
  58   const TimeTickPair& ticks = events_[key];
  59   if (!ticks.first.is_null() && !ticks.second.is_null()) {
  60     UpdateBound(ticks.first, ticks.second);
  61     events_.erase(key);
  62     return;
  63   }
  64
  65   if (events_.size() > kMaxEventTimesMapSize) {
  66     EventMap::iterator i = ModMapOldest(&events_);
  67     if (i != events_.end()) {
  68       events_.erase(i);
  69     }
  70   }
  71 }
  72
  73 ReceiverTimeOffsetEstimatorImpl::ReceiverTimeOffsetEstimatorImpl() {
  74 }
  75
  76 ReceiverTimeOffsetEstimatorImpl::~ReceiverTimeOffsetEstimatorImpl() {
  77   DCHECK(thread_checker_.CalledOnValidThread());
  78 }
  79
  80
  81 void ReceiverTimeOffsetEstimatorImpl::OnReceiveFrameEvent(
  82     const FrameEvent& frame_event) {
  83   DCHECK(thread_checker_.CalledOnValidThread());
  84   switch (frame_event.type) {
  85     case FRAME_ACK_SENT:
  86       lower_bound_.SetSent(frame_event.rtp_timestamp,
  87                            0,
  88                            frame_event.media_type == AUDIO_EVENT,
  89                            frame_event.timestamp);
  90       break;
  91     case FRAME_ACK_RECEIVED:
  92       lower_bound_.SetReceived(frame_event.rtp_timestamp,
  93                                0,
  94                                frame_event.media_type == AUDIO_EVENT,
  95                                frame_event.timestamp);
  96       break;
  97     default:
  98       // Ignored
  99       break;
 100   }
 101 }
 102
 103 bool ReceiverTimeOffsetEstimatorImpl::GetReceiverOffsetBounds(
 104     base::TimeDelta* lower_bound,
 105     base::TimeDelta* upper_bound) {
 106   if (!lower_bound_.has_bound() || !upper_bound_.has_bound())
 107     return false;
 108
 109   *lower_bound = -lower_bound_.bound();
 110   *upper_bound = upper_bound_.bound();
 111
 112   // Sanitize the output, we don't want the upper bound to be
 113   // lower than the lower bound, make them the same.
 114   if (upper_bound < lower_bound) {
 115     lower_bound += (lower_bound - upper_bound) / 2;
 116     upper_bound = lower_bound;
 117   }
 118   return true;
 119 }
 120
 121 void ReceiverTimeOffsetEstimatorImpl::OnReceivePacketEvent(
 122     const PacketEvent& packet_event) {
 123   DCHECK(thread_checker_.CalledOnValidThread());
 124   switch (packet_event.type) {
 125     case PACKET_SENT_TO_NETWORK:
 126       upper_bound_.SetSent(packet_event.rtp_timestamp,
 127                            packet_event.packet_id,
 128                            packet_event.media_type == AUDIO_EVENT,
 129                            packet_event.timestamp);
 130       break;
 131     case PACKET_RECEIVED:
 132       upper_bound_.SetReceived(packet_event.rtp_timestamp,
 133                                packet_event.packet_id,
 134                                packet_event.media_type == AUDIO_EVENT,
 135                                packet_event.timestamp);
 136       break;
 137     default:
 138       // Ignored
 139       break;
 140   }
 141 }
 142
 143
 144 }  // namespace cast
 145 }  // namespace media