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
19namespace media {
20class VideoCaptureParams;
21class VideoFrame;
22}  // namespace media
23
24namespace content {
25
26const int kMinFrameWidth = 2;
27const int kMinFrameHeight = 2;
28
29// Returns the nearest even integer closer to zero.
30template<typename IntType>
31IntType 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)
38const bool kAcceleratedSubscriberIsSupported = true;
39#else
40const bool kAcceleratedSubscriberIsSupported = false;
41#endif
42
43class 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.
49class 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                                    const gfx::Rect& damage_rect,
66                                    base::TimeTicks event_time,
67                                    scoped_refptr<media::VideoFrame>* storage,
68                                    CaptureFrameCallback* callback);
69
70  base::TimeDelta min_capture_period() const {
71    return oracle_->min_capture_period();
72  }
73
74  // Returns the current capture resolution.
75  gfx::Size GetCaptureSize() const;
76
77  // Updates capture resolution based on the supplied source size and the
78  // maximum frame size.
79  void UpdateCaptureSize(const gfx::Size& source_size);
80
81  // Stop new captures from happening (but doesn't forget the client).
82  void Stop();
83
84  // Signal an error to the client.
85  void ReportError(const std::string& reason);
86
87 private:
88  friend class base::RefCountedThreadSafe<ThreadSafeCaptureOracle>;
89  virtual ~ThreadSafeCaptureOracle();
90
91  // Callback invoked on completion of all captures.
92  void DidCaptureFrame(
93      int frame_number,
94      const scoped_refptr<media::VideoCaptureDevice::Client::Buffer>& buffer,
95      const scoped_refptr<media::VideoFrame>& frame,
96      base::TimeTicks timestamp,
97      bool success);
98
99  // Protects everything below it.
100  mutable base::Lock lock_;
101
102  // Recipient of our capture activity.
103  scoped_ptr<media::VideoCaptureDevice::Client> client_;
104
105  // Makes the decision to capture a frame.
106  const scoped_ptr<VideoCaptureOracle> oracle_;
107
108  // The video capture parameters used to construct the oracle proxy.
109  media::VideoCaptureParams params_;
110
111  // Indicates if capture size has been updated after construction.
112  bool capture_size_updated_;
113
114  // The current capturing format, as a media::VideoFrame::Format.
115  media::VideoFrame::Format video_frame_format_;
116};
117
118// Keeps track of the video capture source frames and executes copying on the
119// UI BrowserThread.
120class VideoCaptureMachine {
121 public:
122  VideoCaptureMachine() {}
123  virtual ~VideoCaptureMachine() {}
124
125  // Starts capturing. Returns true if succeeded.
126  // Must be run on the UI BrowserThread.
127  virtual bool Start(const scoped_refptr<ThreadSafeCaptureOracle>& oracle_proxy,
128                     const media::VideoCaptureParams& params) = 0;
129
130  // Stops capturing. Must be run on the UI BrowserThread.
131  // |callback| is invoked after the capturing has stopped.
132  virtual void Stop(const base::Closure& callback) = 0;
133
134 private:
135  DISALLOW_COPY_AND_ASSIGN(VideoCaptureMachine);
136};
137
138// The "meat" of a content video capturer.
139//
140// Separating this from the "shell classes" WebContentsVideoCaptureDevice and
141// DesktopCaptureDeviceAura allows safe destruction without needing to block any
142// threads, as well as code sharing.
143//
144// ContentVideoCaptureDeviceCore manages a simple state machine and the pipeline
145// (see notes at top of this file).  It times the start of successive captures
146// and facilitates the processing of each through the stages of the
147// pipeline.
148class CONTENT_EXPORT ContentVideoCaptureDeviceCore
149    : public base::SupportsWeakPtr<ContentVideoCaptureDeviceCore> {
150 public:
151  ContentVideoCaptureDeviceCore(
152      scoped_ptr<VideoCaptureMachine> capture_machine);
153  virtual ~ContentVideoCaptureDeviceCore();
154
155  // Asynchronous requests to change ContentVideoCaptureDeviceCore state.
156  void AllocateAndStart(const media::VideoCaptureParams& params,
157                        scoped_ptr<media::VideoCaptureDevice::Client> client);
158  void StopAndDeAllocate();
159
160 private:
161  // Flag indicating current state.
162  enum State {
163    kIdle,
164    kCapturing,
165    kError
166  };
167
168  void TransitionStateTo(State next_state);
169
170  // Called back in response to StartCaptureMachine().  |success| is true if
171  // capture machine succeeded to start.
172  void CaptureStarted(bool success);
173
174  // Stops capturing and notifies client_ of an error state.
175  void Error(const std::string& reason);
176
177  // Tracks that all activity occurs on the media stream manager's thread.
178  base::ThreadChecker thread_checker_;
179
180  // Current lifecycle state.
181  State state_;
182
183  // Tracks the CaptureMachine that's doing work on our behalf on the UI thread.
184  // This value should never be dereferenced by this class, other than to
185  // create and destroy it on the UI thread.
186  scoped_ptr<VideoCaptureMachine> capture_machine_;
187
188  // Our thread-safe capture oracle which serves as the gateway to the video
189  // capture pipeline. Besides the VideoCaptureDevice itself, it is the only
190  // component of the system with direct access to |client_|.
191  scoped_refptr<ThreadSafeCaptureOracle> oracle_proxy_;
192
193  DISALLOW_COPY_AND_ASSIGN(ContentVideoCaptureDeviceCore);
194};
195
196
197}  // namespace content
198
199#endif  // CONTENT_BROWSER_MEDIA_CAPTURE_CONTENT_VIDEO_CAPTURE_DEVICE_CORE_H_
200