1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
|
// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef REMOTING_HOST_VIDEO_SCHEDULER_H_
#define REMOTING_HOST_VIDEO_SCHEDULER_H_
#include <vector>
#include "base/basictypes.h"
#include "base/memory/ref_counted.h"
#include "base/memory/scoped_ptr.h"
#include "base/time/time.h"
#include "base/timer/timer.h"
#include "remoting/codec/video_encoder.h"
#include "remoting/host/capture_scheduler.h"
#include "remoting/proto/video.pb.h"
#include "third_party/skia/include/core/SkSize.h"
#include "third_party/webrtc/modules/desktop_capture/screen_capturer.h"
namespace base {
class SingleThreadTaskRunner;
} // namespace base
namespace media {
class ScreenCapturer;
} // namespace media
namespace remoting {
class CursorShapeInfo;
namespace protocol {
class CursorShapeInfo;
class CursorShapeStub;
class VideoStub;
} // namespace protocol
// Class responsible for scheduling frame captures from a
// webrtc::ScreenCapturer, delivering them to a VideoEncoder to encode, and
// finally passing the encoded video packets to the specified VideoStub to send
// on the network.
//
// THREADING
//
// This class is supplied TaskRunners to use for capture, encode and network
// operations. Capture, encode and network transmission tasks are interleaved
// as illustrated below:
//
// | CAPTURE ENCODE NETWORK
// | .............
// | . Capture .
// | .............
// | ............
// | . .
// | ............. . .
// | . Capture . . Encode .
// | ............. . .
// | . .
// | ............
// | ............. ............ ..........
// | . Capture . . . . Send .
// | ............. . . ..........
// | . Encode .
// | . .
// | . .
// | ............
// | Time
// v
//
// VideoScheduler would ideally schedule captures so as to saturate the slowest
// of the capture, encode and network processes. However, it also needs to
// rate-limit captures to avoid overloading the host system, either by consuming
// too much CPU, or hogging the host's graphics subsystem.
class VideoScheduler : public base::RefCountedThreadSafe<VideoScheduler>,
public webrtc::DesktopCapturer::Callback,
public webrtc::ScreenCapturer::MouseShapeObserver {
public:
// Creates a VideoScheduler running capture, encode and network tasks on the
// supplied TaskRunners. Video and cursor shape updates will be pumped to
// |video_stub| and |client_stub|, which must remain valid until Stop() is
// called. |capturer| is used to capture frames.
VideoScheduler(
scoped_refptr<base::SingleThreadTaskRunner> capture_task_runner,
scoped_refptr<base::SingleThreadTaskRunner> encode_task_runner,
scoped_refptr<base::SingleThreadTaskRunner> network_task_runner,
scoped_ptr<webrtc::ScreenCapturer> capturer,
scoped_ptr<VideoEncoder> encoder,
protocol::CursorShapeStub* cursor_stub,
protocol::VideoStub* video_stub);
// webrtc::DesktopCapturer::Callback implementation.
virtual webrtc::SharedMemory* CreateSharedMemory(size_t size) OVERRIDE;
virtual void OnCaptureCompleted(webrtc::DesktopFrame* frame) OVERRIDE;
// webrtc::ScreenCapturer::MouseShapeObserver implementation.
virtual void OnCursorShapeChanged(
webrtc::MouseCursorShape* cursor_shape) OVERRIDE;
// Starts scheduling frame captures.
void Start();
// Stop scheduling frame captures. This object cannot be re-used once
// it has been stopped.
void Stop();
// Pauses or resumes scheduling of frame captures. Pausing/resuming captures
// only affects capture scheduling and does not stop/start the capturer.
void Pause(bool pause);
// Updates the sequence number embedded in VideoPackets.
// Sequence numbers are used for performance measurements.
void UpdateSequenceNumber(int64 sequence_number);
private:
friend class base::RefCountedThreadSafe<VideoScheduler>;
virtual ~VideoScheduler();
// Capturer thread ----------------------------------------------------------
// Starts the capturer on the capture thread.
void StartOnCaptureThread();
// Stops scheduling frame captures on the capture thread.
void StopOnCaptureThread();
// Schedules the next call to CaptureNextFrame.
void ScheduleNextCapture();
// Starts the next frame capture, unless there are already too many pending.
void CaptureNextFrame();
// Called when a frame capture has been encoded & sent to the client.
void FrameCaptureCompleted();
// Network thread -----------------------------------------------------------
// Send |packet| to the client, unless we are in the process of stopping.
void SendVideoPacket(scoped_ptr<VideoPacket> packet);
// Callback passed to |video_stub_| for the last packet in each frame, to
// rate-limit frame captures to network throughput.
void VideoFrameSentCallback();
// Send updated cursor shape to client.
void SendCursorShape(scoped_ptr<protocol::CursorShapeInfo> cursor_shape);
// Encoder thread -----------------------------------------------------------
// Encode a frame, passing generated VideoPackets to SendVideoPacket().
void EncodeFrame(scoped_ptr<webrtc::DesktopFrame> frame,
int64 sequence_number);
void EncodedDataAvailableCallback(int64 sequence_number,
scoped_ptr<VideoPacket> packet);
// Task runners used by this class.
scoped_refptr<base::SingleThreadTaskRunner> capture_task_runner_;
scoped_refptr<base::SingleThreadTaskRunner> encode_task_runner_;
scoped_refptr<base::SingleThreadTaskRunner> network_task_runner_;
// Used to capture frames. Always accessed on the capture thread.
scoped_ptr<webrtc::ScreenCapturer> capturer_;
// Used to encode captured frames. Always accessed on the encode thread.
scoped_ptr<VideoEncoder> encoder_;
// Interfaces through which video frames and cursor shapes are passed to the
// client. These members are always accessed on the network thread.
protocol::CursorShapeStub* cursor_stub_;
protocol::VideoStub* video_stub_;
// Timer used to schedule CaptureNextFrame().
scoped_ptr<base::OneShotTimer<VideoScheduler> > capture_timer_;
// The number of frames being processed, i.e. frames that we are currently
// capturing, encoding or sending. The value is capped at 2 to minimize
// latency.
int pending_frames_;
// Set when the capturer is capturing a frame.
bool capture_pending_;
// True if the previous scheduled capture was skipped.
bool did_skip_frame_;
// True if capture of video frames is paused.
bool is_paused_;
// This is a number updated by client to trace performance.
int64 sequence_number_;
// An object to schedule capturing.
CaptureScheduler scheduler_;
DISALLOW_COPY_AND_ASSIGN(VideoScheduler);
};
} // namespace remoting
#endif // REMOTING_HOST_VIDEO_SCHEDULER_H_
|
