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 #ifndef CONTENT_BROWSER_MEDIA_CAPTURE_CONTENT_VIDEO_CAPTURE_DEVICE_CORE_H_
6 #define CONTENT_BROWSER_MEDIA_CAPTURE_CONTENT_VIDEO_CAPTURE_DEVICE_CORE_H_
7
8 #include <string>
9
10 #include "base/memory/scoped_ptr.h"
11 #include "base/memory/weak_ptr.h"
12 #include "base/threading/thread.h"
13 #include "base/threading/thread_checker.h"
14 #include "content/browser/media/capture/video_capture_oracle.h"
15 #include "content/common/content_export.h"
16 #include "media/base/video_frame.h"
17 #include "media/video/capture/video_capture_device.h"
18
19 namespace media {
20 class VideoCaptureParams;
21 class VideoFrame;
22 } // namespace media
23
24 namespace content {
25
26 const int kMinFrameWidth = 2;
27 const int kMinFrameHeight = 2;
28
29 // Returns the nearest even integer closer to zero.
30 template<typename IntType>
MakeEven(IntType x)31 IntType MakeEven(IntType x) {
32 return x & static_cast<IntType>(-2);
33 }
34
35 // TODO(nick): Remove this once frame subscription is supported on Aura and
36 // Linux.
37 #if (defined(OS_WIN) || defined(OS_MACOSX)) || defined(USE_AURA)
38 const bool kAcceleratedSubscriberIsSupported = true;
39 #else
40 const bool kAcceleratedSubscriberIsSupported = false;
41 #endif
42
43 class VideoCaptureMachine;
44
45 // Thread-safe, refcounted proxy to the VideoCaptureOracle. This proxy wraps
46 // the VideoCaptureOracle, which decides which frames to capture, and a
47 // VideoCaptureDevice::Client, which allocates and receives the captured
48 // frames, in a lock to synchronize state between the two.
49 class ThreadSafeCaptureOracle
50 : public base::RefCountedThreadSafe<ThreadSafeCaptureOracle> {
51 public:
52 ThreadSafeCaptureOracle(scoped_ptr<media::VideoCaptureDevice::Client> client,
53 scoped_ptr<VideoCaptureOracle> oracle,
54 const media::VideoCaptureParams& params);
55
56 // Called when a captured frame is available or an error has occurred.
57 // If |success| is true then |frame| is valid and |timestamp| indicates when
58 // the frame was painted.
59 // If |success| is false, all other parameters are invalid.
60 typedef base::Callback<void(const scoped_refptr<media::VideoFrame>& frame,
61 base::TimeTicks timestamp,
62 bool success)> CaptureFrameCallback;
63
64 bool ObserveEventAndDecideCapture(VideoCaptureOracle::Event event,
65 base::TimeTicks event_time,
66 scoped_refptr<media::VideoFrame>* storage,
67 CaptureFrameCallback* callback);
68
capture_period()69 base::TimeDelta capture_period() const {
70 return oracle_->capture_period();
71 }
72
73 // Returns the current capture resolution.
74 gfx::Size GetCaptureSize() const;
75
76 // Updates capture resolution based on the supplied source size and the
77 // maximum frame size.
78 void UpdateCaptureSize(const gfx::Size& source_size);
79
80 // Stop new captures from happening (but doesn't forget the client).
81 void Stop();
82
83 // Signal an error to the client.
84 void ReportError(const std::string& reason);
85
86 private:
87 friend class base::RefCountedThreadSafe<ThreadSafeCaptureOracle>;
88 virtual ~ThreadSafeCaptureOracle();
89
90 // Callback invoked on completion of all captures.
91 void DidCaptureFrame(
92 int frame_number,
93 const scoped_refptr<media::VideoCaptureDevice::Client::Buffer>& buffer,
94 const scoped_refptr<media::VideoFrame>& frame,
95 base::TimeTicks timestamp,
96 bool success);
97
98 // Protects everything below it.
99 mutable base::Lock lock_;
100
101 // Recipient of our capture activity.
102 scoped_ptr<media::VideoCaptureDevice::Client> client_;
103
104 // Makes the decision to capture a frame.
105 const scoped_ptr<VideoCaptureOracle> oracle_;
106
107 // The video capture parameters used to construct the oracle proxy.
108 media::VideoCaptureParams params_;
109
110 // Indicates if capture size has been updated after construction.
111 bool capture_size_updated_;
112
113 // The current capturing format, as a media::VideoFrame::Format.
114 media::VideoFrame::Format video_frame_format_;
115 };
116
117 // Keeps track of the video capture source frames and executes copying on the
118 // UI BrowserThread.
119 class VideoCaptureMachine {
120 public:
VideoCaptureMachine()121 VideoCaptureMachine() : started_(false) {}
~VideoCaptureMachine()122 virtual ~VideoCaptureMachine() {}
123
124 // This should only be checked on the UI thread.
started()125 bool started() const { return started_; }
126
127 // Starts capturing. Returns true if succeeded.
128 // Must be run on the UI BrowserThread.
129 virtual bool Start(const scoped_refptr<ThreadSafeCaptureOracle>& oracle_proxy,
130 const media::VideoCaptureParams& params) = 0;
131
132 // Stops capturing. Must be run on the UI BrowserThread.
133 // |callback| is invoked after the capturing has stopped.
134 virtual void Stop(const base::Closure& callback) = 0;
135
136 protected:
137 bool started_;
138
139 private:
140 DISALLOW_COPY_AND_ASSIGN(VideoCaptureMachine);
141 };
142
143 // The "meat" of a content video capturer.
144 //
145 // Separating this from the "shell classes" WebContentsVideoCaptureDevice and
146 // DesktopCaptureDeviceAura allows safe destruction without needing to block any
147 // threads (e.g., the IO BrowserThread), as well as code sharing.
148 //
149 // ContentVideoCaptureDeviceCore manages a simple state machine and the pipeline
150 // (see notes at top of this file). It times the start of successive captures
151 // and facilitates the processing of each through the stages of the
152 // pipeline.
153 class CONTENT_EXPORT ContentVideoCaptureDeviceCore
154 : public base::SupportsWeakPtr<ContentVideoCaptureDeviceCore> {
155 public:
156 ContentVideoCaptureDeviceCore(
157 scoped_ptr<VideoCaptureMachine> capture_machine);
158 virtual ~ContentVideoCaptureDeviceCore();
159
160 // Asynchronous requests to change ContentVideoCaptureDeviceCore state.
161 void AllocateAndStart(const media::VideoCaptureParams& params,
162 scoped_ptr<media::VideoCaptureDevice::Client> client);
163 void StopAndDeAllocate();
164
165 private:
166 // Flag indicating current state.
167 enum State {
168 kIdle,
169 kCapturing,
170 kError
171 };
172
173 void TransitionStateTo(State next_state);
174
175 // Called on the IO thread in response to StartCaptureMachine().
176 // |success| is true if capture machine succeeded to start.
177 void CaptureStarted(bool success);
178
179 // Stops capturing and notifies client_ of an error state.
180 void Error(const std::string& reason);
181
182 // Tracks that all activity occurs on the media stream manager's thread.
183 base::ThreadChecker thread_checker_;
184
185 // Current lifecycle state.
186 State state_;
187
188 // Tracks the CaptureMachine that's doing work on our behalf on the UI thread.
189 // This value should never be dereferenced by this class, other than to
190 // create and destroy it on the UI thread.
191 scoped_ptr<VideoCaptureMachine> capture_machine_;
192
193 // Our thread-safe capture oracle which serves as the gateway to the video
194 // capture pipeline. Besides the VideoCaptureDevice itself, it is the only
195 // component of the/ system with direct access to |client_|.
196 scoped_refptr<ThreadSafeCaptureOracle> oracle_proxy_;
197
198 DISALLOW_COPY_AND_ASSIGN(ContentVideoCaptureDeviceCore);
199 };
200
201
202 } // namespace content
203
204 #endif // CONTENT_BROWSER_MEDIA_CAPTURE_CONTENT_VIDEO_CAPTURE_DEVICE_CORE_H_
205