1 // Copyright (c) 2012 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_VIDEO_SCHEDULER_H_ 6 #define REMOTING_HOST_VIDEO_SCHEDULER_H_ 7 8 #include <vector> 9 10 #include "base/basictypes.h" 11 #include "base/memory/ref_counted.h" 12 #include "base/memory/scoped_ptr.h" 13 #include "base/time/time.h" 14 #include "base/timer/timer.h" 15 #include "remoting/codec/video_encoder.h" 16 #include "remoting/host/capture_scheduler.h" 17 #include "remoting/proto/video.pb.h" 18 #include "third_party/skia/include/core/SkSize.h" 19 #include "third_party/webrtc/modules/desktop_capture/screen_capturer.h" 20 21 namespace base { 22 class SingleThreadTaskRunner; 23 } // namespace base 24 25 namespace media { 26 class ScreenCapturer; 27 } // namespace media 28 29 namespace remoting { 30 31 class CursorShapeInfo; 32 33 namespace protocol { 34 class CursorShapeInfo; 35 class CursorShapeStub; 36 class VideoStub; 37 } // namespace protocol 38 39 // Class responsible for scheduling frame captures from a 40 // webrtc::ScreenCapturer, delivering them to a VideoEncoder to encode, and 41 // finally passing the encoded video packets to the specified VideoStub to send 42 // on the network. 43 // 44 // THREADING 45 // 46 // This class is supplied TaskRunners to use for capture, encode and network 47 // operations. Capture, encode and network transmission tasks are interleaved 48 // as illustrated below: 49 // 50 // | CAPTURE ENCODE NETWORK 51 // | ............. 52 // | . Capture . 53 // | ............. 54 // | ............ 55 // | . . 56 // | ............. . . 57 // | . Capture . . Encode . 58 // | ............. . . 59 // | . . 60 // | ............ 61 // | ............. ............ .......... 62 // | . Capture . . . . Send . 63 // | ............. . . .......... 64 // | . Encode . 65 // | . . 66 // | . . 67 // | ............ 68 // | Time 69 // v 70 // 71 // VideoScheduler would ideally schedule captures so as to saturate the slowest 72 // of the capture, encode and network processes. However, it also needs to 73 // rate-limit captures to avoid overloading the host system, either by consuming 74 // too much CPU, or hogging the host's graphics subsystem. 75 76 class VideoScheduler : public base::RefCountedThreadSafe<VideoScheduler>, 77 public webrtc::DesktopCapturer::Callback, 78 public webrtc::ScreenCapturer::MouseShapeObserver { 79 public: 80 // Creates a VideoScheduler running capture, encode and network tasks on the 81 // supplied TaskRunners. Video and cursor shape updates will be pumped to 82 // |video_stub| and |client_stub|, which must remain valid until Stop() is 83 // called. |capturer| is used to capture frames. 84 VideoScheduler( 85 scoped_refptr<base::SingleThreadTaskRunner> capture_task_runner, 86 scoped_refptr<base::SingleThreadTaskRunner> encode_task_runner, 87 scoped_refptr<base::SingleThreadTaskRunner> network_task_runner, 88 scoped_ptr<webrtc::ScreenCapturer> capturer, 89 scoped_ptr<VideoEncoder> encoder, 90 protocol::CursorShapeStub* cursor_stub, 91 protocol::VideoStub* video_stub); 92 93 // webrtc::DesktopCapturer::Callback implementation. 94 virtual webrtc::SharedMemory* CreateSharedMemory(size_t size) OVERRIDE; 95 virtual void OnCaptureCompleted(webrtc::DesktopFrame* frame) OVERRIDE; 96 97 // webrtc::ScreenCapturer::MouseShapeObserver implementation. 98 virtual void OnCursorShapeChanged( 99 webrtc::MouseCursorShape* cursor_shape) OVERRIDE; 100 101 // Starts scheduling frame captures. 102 void Start(); 103 104 // Stop scheduling frame captures. This object cannot be re-used once 105 // it has been stopped. 106 void Stop(); 107 108 // Pauses or resumes scheduling of frame captures. Pausing/resuming captures 109 // only affects capture scheduling and does not stop/start the capturer. 110 void Pause(bool pause); 111 112 // Updates the sequence number embedded in VideoPackets. 113 // Sequence numbers are used for performance measurements. 114 void UpdateSequenceNumber(int64 sequence_number); 115 116 private: 117 friend class base::RefCountedThreadSafe<VideoScheduler>; 118 virtual ~VideoScheduler(); 119 120 // Capturer thread ---------------------------------------------------------- 121 122 // Starts the capturer on the capture thread. 123 void StartOnCaptureThread(); 124 125 // Stops scheduling frame captures on the capture thread. 126 void StopOnCaptureThread(); 127 128 // Schedules the next call to CaptureNextFrame. 129 void ScheduleNextCapture(); 130 131 // Starts the next frame capture, unless there are already too many pending. 132 void CaptureNextFrame(); 133 134 // Called when a frame capture has been encoded & sent to the client. 135 void FrameCaptureCompleted(); 136 137 // Network thread ----------------------------------------------------------- 138 139 // Send |packet| to the client, unless we are in the process of stopping. 140 void SendVideoPacket(scoped_ptr<VideoPacket> packet); 141 142 // Callback passed to |video_stub_| for the last packet in each frame, to 143 // rate-limit frame captures to network throughput. 144 void VideoFrameSentCallback(); 145 146 // Send updated cursor shape to client. 147 void SendCursorShape(scoped_ptr<protocol::CursorShapeInfo> cursor_shape); 148 149 // Encoder thread ----------------------------------------------------------- 150 151 // Encode a frame, passing generated VideoPackets to SendVideoPacket(). 152 void EncodeFrame(scoped_ptr<webrtc::DesktopFrame> frame, 153 int64 sequence_number); 154 155 void EncodedDataAvailableCallback(int64 sequence_number, 156 scoped_ptr<VideoPacket> packet); 157 158 // Task runners used by this class. 159 scoped_refptr<base::SingleThreadTaskRunner> capture_task_runner_; 160 scoped_refptr<base::SingleThreadTaskRunner> encode_task_runner_; 161 scoped_refptr<base::SingleThreadTaskRunner> network_task_runner_; 162 163 // Used to capture frames. Always accessed on the capture thread. 164 scoped_ptr<webrtc::ScreenCapturer> capturer_; 165 166 // Used to encode captured frames. Always accessed on the encode thread. 167 scoped_ptr<VideoEncoder> encoder_; 168 169 // Interfaces through which video frames and cursor shapes are passed to the 170 // client. These members are always accessed on the network thread. 171 protocol::CursorShapeStub* cursor_stub_; 172 protocol::VideoStub* video_stub_; 173 174 // Timer used to schedule CaptureNextFrame(). 175 scoped_ptr<base::OneShotTimer<VideoScheduler> > capture_timer_; 176 177 // The number of frames being processed, i.e. frames that we are currently 178 // capturing, encoding or sending. The value is capped at 2 to minimize 179 // latency. 180 int pending_frames_; 181 182 // Set when the capturer is capturing a frame. 183 bool capture_pending_; 184 185 // True if the previous scheduled capture was skipped. 186 bool did_skip_frame_; 187 188 // True if capture of video frames is paused. 189 bool is_paused_; 190 191 // This is a number updated by client to trace performance. 192 int64 sequence_number_; 193 194 // An object to schedule capturing. 195 CaptureScheduler scheduler_; 196 197 DISALLOW_COPY_AND_ASSIGN(VideoScheduler); 198 }; 199 200 } // namespace remoting 201 202 #endif // REMOTING_HOST_VIDEO_SCHEDULER_H_ 203
