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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 // This class maintains a bi-directional RTCP connection with a remote
6 // peer.
7 
8 #ifndef MEDIA_CAST_RTCP_RTCP_H_
9 #define MEDIA_CAST_RTCP_RTCP_H_
10 
11 #include <map>
12 #include <queue>
13 #include <string>
14 
15 #include "base/basictypes.h"
16 #include "base/memory/scoped_ptr.h"
17 #include "base/memory/weak_ptr.h"
18 #include "base/time/tick_clock.h"
19 #include "base/time/time.h"
20 #include "media/cast/cast_config.h"
21 #include "media/cast/cast_defines.h"
22 #include "media/cast/common/clock_drift_smoother.h"
23 #include "media/cast/net/cast_transport_defines.h"
24 #include "media/cast/net/cast_transport_sender.h"
25 #include "media/cast/net/rtcp/receiver_rtcp_event_subscriber.h"
26 #include "media/cast/net/rtcp/rtcp_builder.h"
27 #include "media/cast/net/rtcp/rtcp_defines.h"
28 
29 namespace media {
30 namespace cast {
31 
32 class LocalRtcpReceiverFeedback;
33 class PacedPacketSender;
34 class RtcpReceiver;
35 class RtcpBuilder;
36 
37 typedef std::pair<uint32, base::TimeTicks> RtcpSendTimePair;
38 typedef std::map<uint32, base::TimeTicks> RtcpSendTimeMap;
39 typedef std::queue<RtcpSendTimePair> RtcpSendTimeQueue;
40 
41 class RtpReceiverStatistics {
42  public:
43   virtual void GetStatistics(uint8* fraction_lost,
44                              uint32* cumulative_lost,  // 24 bits valid.
45                              uint32* extended_high_sequence_number,
46                              uint32* jitter) = 0;
47 
~RtpReceiverStatistics()48   virtual ~RtpReceiverStatistics() {}
49 };
50 
51 // TODO(hclam): This should be renamed to RtcpSession.
52 class Rtcp {
53  public:
54   Rtcp(const RtcpCastMessageCallback& cast_callback,
55        const RtcpRttCallback& rtt_callback,
56        const RtcpLogMessageCallback& log_callback,
57        base::TickClock* clock,  // Not owned.
58        PacedPacketSender* packet_sender,  // Not owned.
59        uint32 local_ssrc,
60        uint32 remote_ssrc);
61 
62   virtual ~Rtcp();
63 
64   // Send a RTCP sender report.
65   // |current_time| is the current time reported by a tick clock.
66   // |current_time_as_rtp_timestamp| is the corresponding RTP timestamp.
67   // |send_packet_count| is the number of packets sent.
68   // |send_octet_count| is the number of octets sent.
69   void SendRtcpFromRtpSender(
70       base::TimeTicks current_time,
71       uint32 current_time_as_rtp_timestamp,
72       uint32 send_packet_count,
73       size_t send_octet_count);
74 
75   // |cast_message| and |rtcp_events| is optional; if |cast_message| is
76   // provided the RTCP receiver report will append a Cast message containing
77   // Acks and Nacks; |target_delay| is sent together with |cast_message|.
78   // If |rtcp_events| is provided the RTCP receiver report will append the
79   // log messages.
80   void SendRtcpFromRtpReceiver(
81       const RtcpCastMessage* cast_message,
82       base::TimeDelta target_delay,
83       const ReceiverRtcpEventSubscriber::RtcpEventMultiMap* rtcp_events,
84       RtpReceiverStatistics* rtp_receiver_statistics);
85 
86   // Submit a received packet to this object. The packet will be parsed
87   // and used to maintain a RTCP session.
88   // Returns false if this is not a RTCP packet or it is not directed to
89   // this session, e.g. SSRC doesn't match.
90   bool IncomingRtcpPacket(const uint8* data, size_t length);
91 
92   // If available, returns true and sets the output arguments to the latest
93   // lip-sync timestamps gleaned from the sender reports.  While the sender
94   // provides reference NTP times relative to its own wall clock, the
95   // |reference_time| returned here has been translated to the local
96   // CastEnvironment clock.
97   bool GetLatestLipSyncTimes(uint32* rtp_timestamp,
98                              base::TimeTicks* reference_time) const;
99 
100   void OnReceivedReceiverLog(const RtcpReceiverLogMessage& receiver_log);
101 
102   // If greater than zero, this is the last measured network round trip time.
current_round_trip_time()103   base::TimeDelta current_round_trip_time() const {
104     return current_round_trip_time_;
105   }
106 
107   static bool IsRtcpPacket(const uint8* packet, size_t length);
108   static uint32 GetSsrcOfSender(const uint8* rtcp_buffer, size_t length);
109 
110  protected:
111   void OnReceivedNtp(uint32 ntp_seconds, uint32 ntp_fraction);
112   void OnReceivedLipSyncInfo(uint32 rtp_timestamp,
113                              uint32 ntp_seconds,
114                              uint32 ntp_fraction);
115 
116  private:
117   void OnReceivedDelaySinceLastReport(uint32 last_report,
118                                       uint32 delay_since_last_report);
119 
120   void OnReceivedCastFeedback(const RtcpCastMessage& cast_message);
121 
122   void SaveLastSentNtpTime(const base::TimeTicks& now,
123                            uint32 last_ntp_seconds,
124                            uint32 last_ntp_fraction);
125 
126   // Remove duplicate events in |receiver_log|.
127   // Returns true if any events remain.
128   bool DedupeReceiverLog(RtcpReceiverLogMessage* receiver_log);
129 
130   const RtcpCastMessageCallback cast_callback_;
131   const RtcpRttCallback rtt_callback_;
132   const RtcpLogMessageCallback log_callback_;
133   base::TickClock* const clock_;  // Not owned by this class.
134   RtcpBuilder rtcp_builder_;
135   PacedPacketSender* packet_sender_;  // Not owned.
136   const uint32 local_ssrc_;
137   const uint32 remote_ssrc_;
138 
139   RtcpSendTimeMap last_reports_sent_map_;
140   RtcpSendTimeQueue last_reports_sent_queue_;
141 
142   // The truncated (i.e., 64-->32-bit) NTP timestamp provided in the last report
143   // from the remote peer, along with the local time at which the report was
144   // received.  These values are used for ping-pong'ing NTP timestamps between
145   // the peers so that they can estimate the network's round-trip time.
146   uint32 last_report_truncated_ntp_;
147   base::TimeTicks time_last_report_received_;
148 
149   // Maintains a smoothed offset between the local clock and the remote clock.
150   // Calling this member's Current() method is only valid if
151   // |time_last_report_received_| is not "null."
152   ClockDriftSmoother local_clock_ahead_by_;
153 
154   // Latest "lip sync" info from the sender.  The sender provides the RTP
155   // timestamp of some frame of its choosing and also a corresponding reference
156   // NTP timestamp sampled from a clock common to all media streams.  It is
157   // expected that the sender will update this data regularly and in a timely
158   // manner (e.g., about once per second).
159   uint32 lip_sync_rtp_timestamp_;
160   uint64 lip_sync_ntp_timestamp_;
161 
162   // The last measured network round trip time.  This is updated with each
163   // sender report --> receiver report round trip.  If this is zero, then the
164   // round trip time has not been measured yet.
165   base::TimeDelta current_round_trip_time_;
166 
167   base::TimeTicks largest_seen_timestamp_;
168 
169   // For extending received ACK frame IDs from 8-bit to 32-bit.
170   FrameIdWrapHelper ack_frame_id_wrap_helper_;
171 
172   // Maintains a history of receiver events.
173   typedef std::pair<uint64, uint64> ReceiverEventKey;
174   base::hash_set<ReceiverEventKey> receiver_event_key_set_;
175   std::queue<ReceiverEventKey> receiver_event_key_queue_;
176 
177   DISALLOW_COPY_AND_ASSIGN(Rtcp);
178 };
179 
180 }  // namespace cast
181 }  // namespace media
182 
183 #endif  // MEDIA_CAST_RTCP_RTCP_H_
184