content/browser/renderer_host/media/video_capture_device_impl.h

   1 // Copyright 2013 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_RENDERER_HOST_VIDEO_CAPTURE_DEVICE_IMPL_H_
   6 #define CONTENT_BROWSER_RENDERER_HOST_VIDEO_CAPTURE_DEVICE_IMPL_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/renderer_host/media/video_capture_oracle.h"
  15 #include "content/common/content_export.h"
  16 #include "media/video/capture/video_capture_device.h"
  17
  18 namespace content {
  19
  20 const int kMinFrameWidth = 2;
  21 const int kMinFrameHeight = 2;
  22
  23 // Returns the nearest even integer closer to zero.
  24 template<typename IntType>
  25 IntType MakeEven(IntType x) {
  26   return x & static_cast<IntType>(-2);
  27 }
  28
  29 // TODO(nick): Remove this once frame subscription is supported on Aura and
  30 // Linux.
  31 #if (defined(OS_WIN) || defined(OS_MACOSX)) || defined(USE_AURA)
  32 const bool kAcceleratedSubscriberIsSupported = true;
  33 #else
  34 const bool kAcceleratedSubscriberIsSupported = false;
  35 #endif
  36
  37 class VideoCaptureMachine;
  38
  39 // Thread-safe, refcounted proxy to the VideoCaptureOracle.  This proxy wraps
  40 // the VideoCaptureOracle, which decides which frames to capture, and a
  41 // VideoCaptureDevice::Client, which allocates and receives the captured
  42 // frames, in a lock to synchronize state between the two.
  43 class ThreadSafeCaptureOracle
  44     : public base::RefCountedThreadSafe<ThreadSafeCaptureOracle> {
  45  public:
  46   ThreadSafeCaptureOracle(scoped_ptr<media::VideoCaptureDevice::Client> client,
  47                           scoped_ptr<VideoCaptureOracle> oracle,
  48                           const media::VideoCaptureParams& params);
  49
  50   // Called when a captured frame is available or an error has occurred.
  51   // If |success| is true then the frame provided is valid and |timestamp|
  52   // indicates when the frame was painted.
  53   // If |success| is false, both the frame provided and |timestamp| are invalid.
  54   typedef base::Callback<void(base::Time timestamp, bool success)>
  55       CaptureFrameCallback;
  56
  57   bool ObserveEventAndDecideCapture(VideoCaptureOracle::Event event,
  58                                     base::Time event_time,
  59                                     scoped_refptr<media::VideoFrame>* storage,
  60                                     CaptureFrameCallback* callback);
  61
  62   base::TimeDelta capture_period() const {
  63     return oracle_->capture_period();
  64   }
  65
  66   // Updates capture resolution based on the supplied source size and the
  67   // maximum frame size.
  68   void UpdateCaptureSize(const gfx::Size& source_size);
  69
  70   // Stop new captures from happening (but doesn't forget the client).
  71   void Stop();
  72
  73   // Signal an error to the client.
  74   void ReportError();
  75
  76  private:
  77   friend class base::RefCountedThreadSafe<ThreadSafeCaptureOracle>;
  78   virtual ~ThreadSafeCaptureOracle();
  79
  80   // Callback invoked on completion of all captures.
  81   void DidCaptureFrame(
  82       scoped_refptr<media::VideoCaptureDevice::Client::Buffer> buffer,
  83       int frame_number,
  84       base::Time timestamp,
  85       bool success);
  86   // Protects everything below it.
  87   base::Lock lock_;
  88
  89   // Recipient of our capture activity.
  90   scoped_ptr<media::VideoCaptureDevice::Client> client_;
  91
  92   // Makes the decision to capture a frame.
  93   const scoped_ptr<VideoCaptureOracle> oracle_;
  94
  95   // The video capture parameters used to construct the oracle proxy.
  96   const media::VideoCaptureParams params_;
  97
  98   // Indicates if capture size has been updated after construction.
  99   bool capture_size_updated_;
 100
 101   // The current capturing resolution and frame rate.
 102   gfx::Size capture_size_;
 103   int frame_rate_;
 104 };
 105
 106 // Keeps track of the video capture source frames and executes copying on the
 107 // UI BrowserThread.
 108 class VideoCaptureMachine {
 109  public:
 110   VideoCaptureMachine() : started_(false) {}
 111   virtual ~VideoCaptureMachine() {}
 112
 113   // This should only be checked on the UI thread.
 114   bool started() const { return started_; }
 115
 116   // Starts capturing. Returns true if succeeded.
 117   // Must be run on the UI BrowserThread.
 118   virtual bool Start(
 119       const scoped_refptr<ThreadSafeCaptureOracle>& oracle_proxy) = 0;
 120
 121   // Stops capturing. Must be run on the UI BrowserThread.
 122   virtual void Stop() = 0;
 123
 124  protected:
 125   bool started_;
 126
 127  private:
 128   DISALLOW_COPY_AND_ASSIGN(VideoCaptureMachine);
 129 };
 130
 131 // The "meat" of the video capture implementation.
 132 //
 133 // Separating this from the "shell classes" WebContentsVideoCaptureDevice and
 134 // BrowserCompositorCaptureDevice allows safe destruction without needing to
 135 // block any threads (e.g., the IO BrowserThread), as well as code sharing.
 136 //
 137 // VideoCaptureDeviceImpl manages a simple state machine and the pipeline (see
 138 // notes at top of this file).  It times the start of successive
 139 // captures and facilitates the processing of each through the stages of the
 140 // pipeline.
 141 class CONTENT_EXPORT VideoCaptureDeviceImpl
 142     : public base::SupportsWeakPtr<VideoCaptureDeviceImpl> {
 143  public:
 144   VideoCaptureDeviceImpl(scoped_ptr<VideoCaptureMachine> capture_machine);
 145   virtual ~VideoCaptureDeviceImpl();
 146
 147   // Asynchronous requests to change VideoCaptureDeviceImpl state.
 148   void AllocateAndStart(const media::VideoCaptureParams& params,
 149                         scoped_ptr<media::VideoCaptureDevice::Client> client);
 150   void StopAndDeAllocate();
 151
 152  private:
 153   // Flag indicating current state.
 154   enum State {
 155     kIdle,
 156     kCapturing,
 157     kError
 158   };
 159
 160   void TransitionStateTo(State next_state);
 161
 162   // Called on the IO thread in response to StartCaptureMachine().
 163   // |success| is true if capture machine succeeded to start.
 164   void CaptureStarted(bool success);
 165
 166   // Stops capturing and notifies client_ of an error state.
 167   void Error();
 168
 169   // Tracks that all activity occurs on the media stream manager's thread.
 170   base::ThreadChecker thread_checker_;
 171
 172   // Current lifecycle state.
 173   State state_;
 174
 175   // Tracks the CaptureMachine that's doing work on our behalf on the UI thread.
 176   // This value should never be dereferenced by this class, other than to
 177   // create and destroy it on the UI thread.
 178   scoped_ptr<VideoCaptureMachine> capture_machine_;
 179
 180   // Our thread-safe capture oracle which serves as the gateway to the video
 181   // capture pipeline. Besides the WCVCD itself, it is the only component of the
 182   // system with direct access to |client_|.
 183   scoped_refptr<ThreadSafeCaptureOracle> oracle_proxy_;
 184
 185   DISALLOW_COPY_AND_ASSIGN(VideoCaptureDeviceImpl);
 186 };
 187
 188
 189 }  // namespace content
 190
 191 #endif  // CONTENT_BROWSER_RENDERER_HOST_VIDEO_CAPTURE_DEVICE_IMPL_H_