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.
5 #ifndef MEDIA_CAST_LOGGING_RECEIVER_TIME_OFFSET_ESTIMATOR_IMPL_H_
6 #define MEDIA_CAST_LOGGING_RECEIVER_TIME_OFFSET_ESTIMATOR_IMPL_H_
8 #include "base/time/time.h"
9 #include "base/threading/thread_checker.h"
10 #include "media/cast/logging/logging_defines.h"
11 #include "media/cast/logging/receiver_time_offset_estimator.h"
16 // This implementation listens to three types of events:
17 // 1. kVideoFrameEncoded (sender side)
18 // 2. kVideoAckSent (receiver side)
19 // 3. kVideoAckReceived (sender side)
20 // There is a causal relationship between these events in that these events
21 // must happen in order. This class obtains the lower and upper bounds for
22 // the offset by taking the difference of timestamps (2) - (1) and (2) - (3),
24 // The bound will become better as the latency between the events decreases.
25 class ReceiverTimeOffsetEstimatorImpl : public ReceiverTimeOffsetEstimator {
27 ReceiverTimeOffsetEstimatorImpl();
29 virtual ~ReceiverTimeOffsetEstimatorImpl();
31 // RawEventSubscriber implementations.
32 virtual void OnReceiveFrameEvent(const FrameEvent& frame_event) OVERRIDE;
33 virtual void OnReceivePacketEvent(const PacketEvent& packet_event) OVERRIDE;
35 // ReceiverTimeOffsetEstimator implementation.
36 virtual bool GetReceiverOffsetBounds(base::TimeDelta* lower_bound,
37 base::TimeDelta* upper_bound) OVERRIDE;
41 base::TimeTicks event_a_time;
42 base::TimeTicks event_b_time;
43 base::TimeTicks event_c_time;
46 typedef std::map<RtpTimestamp, EventTimes> EventTimesMap;
48 void UpdateOffsetBounds(const EventTimes& event);
50 // Fixed size storage to store event times for recent frames.
51 EventTimesMap event_times_map_;
54 base::TimeDelta offset_lower_bound_;
55 base::TimeDelta offset_upper_bound_;
57 base::ThreadChecker thread_checker_;
58 DISALLOW_COPY_AND_ASSIGN(ReceiverTimeOffsetEstimatorImpl);
64 #endif // MEDIA_CAST_LOGGING_RECEIVER_TIME_OFFSET_ESTIMATOR_IMPL_H_