1/*
2 *  Copyright (c) 2012 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_PACING_PACED_SENDER_H_
12#define WEBRTC_MODULES_PACING_PACED_SENDER_H_
13
14#include <list>
15#include <set>
16
17#include "webrtc/base/scoped_ptr.h"
18#include "webrtc/base/thread_annotations.h"
19#include "webrtc/modules/include/module.h"
20#include "webrtc/modules/rtp_rtcp/include/rtp_rtcp_defines.h"
21#include "webrtc/typedefs.h"
22
23namespace webrtc {
24class BitrateProber;
25class Clock;
26class CriticalSectionWrapper;
27
28namespace paced_sender {
29class IntervalBudget;
30struct Packet;
31class PacketQueue;
32}  // namespace paced_sender
33
34class PacedSender : public Module, public RtpPacketSender {
35 public:
36  class Callback {
37   public:
38    // Note: packets sent as a result of a callback should not pass by this
39    // module again.
40    // Called when it's time to send a queued packet.
41    // Returns false if packet cannot be sent.
42    virtual bool TimeToSendPacket(uint32_t ssrc,
43                                  uint16_t sequence_number,
44                                  int64_t capture_time_ms,
45                                  bool retransmission) = 0;
46    // Called when it's a good time to send a padding data.
47    // Returns the number of bytes sent.
48    virtual size_t TimeToSendPadding(size_t bytes) = 0;
49
50   protected:
51    virtual ~Callback() {}
52  };
53
54  // Expected max pacer delay in ms. If ExpectedQueueTimeMs() is higher than
55  // this value, the packet producers should wait (eg drop frames rather than
56  // encoding them). Bitrate sent may temporarily exceed target set by
57  // UpdateBitrate() so that this limit will be upheld.
58  static const int64_t kMaxQueueLengthMs;
59  // Pace in kbits/s until we receive first estimate.
60  static const int kDefaultInitialPaceKbps = 2000;
61  // Pacing-rate relative to our target send rate.
62  // Multiplicative factor that is applied to the target bitrate to calculate
63  // the number of bytes that can be transmitted per interval.
64  // Increasing this factor will result in lower delays in cases of bitrate
65  // overshoots from the encoder.
66  static const float kDefaultPaceMultiplier;
67
68  static const size_t kMinProbePacketSize = 200;
69
70  PacedSender(Clock* clock,
71              Callback* callback,
72              int bitrate_kbps,
73              int max_bitrate_kbps,
74              int min_bitrate_kbps);
75
76  virtual ~PacedSender();
77
78  // Temporarily pause all sending.
79  void Pause();
80
81  // Resume sending packets.
82  void Resume();
83
84  // Enable bitrate probing. Enabled by default, mostly here to simplify
85  // testing. Must be called before any packets are being sent to have an
86  // effect.
87  void SetProbingEnabled(bool enabled);
88
89  // Set target bitrates for the pacer.
90  // We will pace out bursts of packets at a bitrate of |max_bitrate_kbps|.
91  // |bitrate_kbps| is our estimate of what we are allowed to send on average.
92  // Padding packets will be utilized to reach |min_bitrate| unless enough media
93  // packets are available.
94  void UpdateBitrate(int bitrate_kbps,
95                     int max_bitrate_kbps,
96                     int min_bitrate_kbps);
97
98  // Returns true if we send the packet now, else it will add the packet
99  // information to the queue and call TimeToSendPacket when it's time to send.
100  void InsertPacket(RtpPacketSender::Priority priority,
101                    uint32_t ssrc,
102                    uint16_t sequence_number,
103                    int64_t capture_time_ms,
104                    size_t bytes,
105                    bool retransmission) override;
106
107  // Returns the time since the oldest queued packet was enqueued.
108  virtual int64_t QueueInMs() const;
109
110  virtual size_t QueueSizePackets() const;
111
112  // Returns the number of milliseconds it will take to send the current
113  // packets in the queue, given the current size and bitrate, ignoring prio.
114  virtual int64_t ExpectedQueueTimeMs() const;
115
116  // Returns the average time since being enqueued, in milliseconds, for all
117  // packets currently in the pacer queue, or 0 if queue is empty.
118  virtual int64_t AverageQueueTimeMs();
119
120  // Returns the number of milliseconds until the module want a worker thread
121  // to call Process.
122  int64_t TimeUntilNextProcess() override;
123
124  // Process any pending packets in the queue(s).
125  int32_t Process() override;
126
127 private:
128  // Updates the number of bytes that can be sent for the next time interval.
129  void UpdateBytesPerInterval(int64_t delta_time_in_ms)
130      EXCLUSIVE_LOCKS_REQUIRED(critsect_);
131
132  bool SendPacket(const paced_sender::Packet& packet)
133      EXCLUSIVE_LOCKS_REQUIRED(critsect_);
134  void SendPadding(size_t padding_needed) EXCLUSIVE_LOCKS_REQUIRED(critsect_);
135
136  Clock* const clock_;
137  Callback* const callback_;
138
139  rtc::scoped_ptr<CriticalSectionWrapper> critsect_;
140  bool paused_ GUARDED_BY(critsect_);
141  bool probing_enabled_;
142  // This is the media budget, keeping track of how many bits of media
143  // we can pace out during the current interval.
144  rtc::scoped_ptr<paced_sender::IntervalBudget> media_budget_
145      GUARDED_BY(critsect_);
146  // This is the padding budget, keeping track of how many bits of padding we're
147  // allowed to send out during the current interval. This budget will be
148  // utilized when there's no media to send.
149  rtc::scoped_ptr<paced_sender::IntervalBudget> padding_budget_
150      GUARDED_BY(critsect_);
151
152  rtc::scoped_ptr<BitrateProber> prober_ GUARDED_BY(critsect_);
153  // Actual configured bitrates (media_budget_ may temporarily be higher in
154  // order to meet pace time constraint).
155  int bitrate_bps_ GUARDED_BY(critsect_);
156  int max_bitrate_kbps_ GUARDED_BY(critsect_);
157
158  int64_t time_last_update_us_ GUARDED_BY(critsect_);
159
160  rtc::scoped_ptr<paced_sender::PacketQueue> packets_ GUARDED_BY(critsect_);
161  uint64_t packet_counter_;
162};
163}  // namespace webrtc
164#endif  // WEBRTC_MODULES_PACING_PACED_SENDER_H_
165