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1 // Copyright (c) 2011 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 #ifndef REMOTING_HOST_CAPTURE_SCHEDULER_H_ | |
6 #define REMOTING_HOST_CAPTURE_SCHEDULER_H_ | |
7 | |
8 #include "base/callback.h" | |
9 #include "base/threading/thread_checker.h" | |
10 #include "base/time/tick_clock.h" | |
11 #include "base/time/time.h" | |
12 #include "base/timer/timer.h" | |
13 #include "remoting/base/running_average.h" | |
14 #include "remoting/protocol/video_feedback_stub.h" | |
15 | |
16 namespace remoting { | |
17 | |
18 class VideoPacket; | |
19 | |
20 // CaptureScheduler is used by the VideoFramePump to schedule frame capturer, | |
21 // taking into account capture delay, encoder delay, network bandwidth, etc. | |
22 // It implements VideoFeedbackStub to receive frame acknowledgments from the | |
23 // client. | |
24 // | |
25 // It attempts to achieve the following goals when scheduling frames: | |
26 // - Keep round-trip latency as low a possible. | |
27 // - Parallelize capture, encode and transmission, to achieve frame rate as | |
28 // close to the target of 30fps as possible. | |
29 // - Limit CPU usage to 50%. | |
30 class CaptureScheduler : public protocol::VideoFeedbackStub { | |
31 public: | |
32 explicit CaptureScheduler(const base::Closure& capture_closure); | |
33 ~CaptureScheduler() override; | |
34 | |
35 // Starts the scheduler. | |
36 void Start(); | |
37 | |
38 // Pauses or unpauses the stream. | |
39 void Pause(bool pause); | |
40 | |
41 // Notifies the scheduler that a capture has been completed. | |
42 void OnCaptureCompleted(); | |
43 | |
44 // Notifies the scheduler that a frame has been encoded. The scheduler can | |
45 // change |packet| if necessary, e.g. set |frame_id|. | |
46 void OnFrameEncoded(VideoPacket* packet); | |
47 | |
48 // Notifies the scheduler that a frame has been sent. | |
49 void OnFrameSent(); | |
50 | |
51 // VideoFeedbackStub interface. | |
52 void ProcessVideoAck(scoped_ptr<VideoAck> video_ack) override; | |
53 | |
54 // Sets minimum interval between frames. | |
55 void set_minimum_interval(base::TimeDelta minimum_interval) { | |
56 minimum_interval_ = minimum_interval; | |
57 } | |
58 | |
59 // Helper functions for tests. | |
60 void SetTickClockForTest(scoped_ptr<base::TickClock> tick_clock); | |
61 void SetTimerForTest(scoped_ptr<base::Timer> timer); | |
62 void SetNumOfProcessorsForTest(int num_of_processors); | |
63 | |
64 private: | |
65 // Schedules |capture_timer_| to call CaptureNextFrame() at appropriate time. | |
66 // Doesn't do anything if next frame cannot be captured yet (e.g. because | |
67 // there are too many frames being processed). | |
68 void ScheduleNextCapture(); | |
69 | |
70 // Called by |capture_timer_|. Calls |capture_closure_| to start capturing a | |
71 // new frame. | |
72 void CaptureNextFrame(); | |
73 | |
74 base::Closure capture_closure_; | |
75 | |
76 scoped_ptr<base::TickClock> tick_clock_; | |
77 | |
78 // Timer used to schedule CaptureNextFrame(). | |
79 scoped_ptr<base::Timer> capture_timer_; | |
80 | |
81 // Minimum interval between frames that determines maximum possible framerate. | |
82 base::TimeDelta minimum_interval_; | |
83 | |
84 int num_of_processors_; | |
85 | |
86 RunningAverage capture_time_; | |
87 RunningAverage encode_time_; | |
88 | |
89 // Number of frames pending encoding. | |
90 int num_encoding_frames_; | |
91 | |
92 // Number of outgoing frames for which we haven't received an acknowledgment. | |
93 int num_unacknowledged_frames_; | |
94 | |
95 // Set to true when capture is pending. | |
96 bool capture_pending_; | |
97 | |
98 // Time at which the last capture started. Used to schedule |capture_timer_|. | |
99 base::TimeTicks last_capture_started_time_; | |
100 | |
101 bool is_paused_; | |
102 | |
103 // Frame ID to be assigned to the next outgoing video frame. | |
104 uint32_t next_frame_id_; | |
105 | |
106 base::ThreadChecker thread_checker_; | |
107 | |
108 DISALLOW_COPY_AND_ASSIGN(CaptureScheduler); | |
109 }; | |
110 | |
111 } // namespace remoting | |
112 | |
113 #endif // REMOTING_HOST_CAPTURE_SCHEDULER_H_ | |
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