content/browser/renderer_host/media/video_capture_controller.h

   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 // VideoCaptureController is the glue between a VideoCaptureDevice and all
   6 // VideoCaptureHosts that have connected to it. A controller exists on behalf of
   7 // one (and only one) VideoCaptureDevice; both are owned by the
   8 // VideoCaptureManager.
   9 //
  10 // The VideoCaptureController is responsible for:
  11 //
  12 //   * Allocating and keeping track of shared memory buffers, and filling them
  13 //     with I420 video frames for IPC communication between VideoCaptureHost (in
  14 //     the browser process) and VideoCaptureMessageFilter (in the renderer
  15 //     process).
  16 //   * Broadcasting the events from a single VideoCaptureDevice, fanning them
  17 //     out to multiple clients.
  18 //   * Keeping track of the clients on behalf of the VideoCaptureManager, making
  19 //     it possible for the Manager to delete the Controller and its Device when
  20 //     there are no clients left.
  21 //
  22 // Interactions between VideoCaptureController and other classes:
  23 //
  24 //   * VideoCaptureController indirectly observes a VideoCaptureDevice
  25 //     by means of its proxy, VideoCaptureDeviceClient, which implements
  26 //     the VideoCaptureDevice::Client interface. The proxy forwards
  27 //     observed events to the VideoCaptureController on the IO thread.
  28 //   * A VideoCaptureController interacts with its clients (VideoCaptureHosts)
  29 //     via the VideoCaptureControllerEventHandler interface.
  30 //   * Conversely, a VideoCaptureControllerEventHandler (typically,
  31 //     VideoCaptureHost) will interact directly with VideoCaptureController to
  32 //     return leased buffers by means of the ReturnBuffer() public method of
  33 //     VCC.
  34 //   * VideoCaptureManager (which owns the VCC) interacts directly with
  35 //     VideoCaptureController through its public methods, to add and remove
  36 //     clients.
  37 //
  38 // VideoCaptureController is not thread safe and operates on the IO thread only.
  39
  40 #ifndef CONTENT_BROWSER_RENDERER_HOST_MEDIA_VIDEO_CAPTURE_CONTROLLER_H_
  41 #define CONTENT_BROWSER_RENDERER_HOST_MEDIA_VIDEO_CAPTURE_CONTROLLER_H_
  42
  43 #include <list>
  44
  45 #include "base/compiler_specific.h"
  46 #include "base/memory/ref_counted.h"
  47 #include "base/memory/scoped_ptr.h"
  48 #include "base/memory/weak_ptr.h"
  49 #include "base/process/process.h"
  50 #include "content/browser/renderer_host/media/video_capture_controller_event_handler.h"
  51 #include "content/common/content_export.h"
  52 #include "content/common/media/video_capture.h"
  53 #include "media/base/video_capture_types.h"
  54 #include "media/video/capture/video_capture_device.h"
  55
  56 namespace content {
  57 class VideoCaptureBufferPool;
  58
  59 class CONTENT_EXPORT VideoCaptureController {
  60  public:
  61   // |max_buffers| is the maximum number of video frame buffers in-flight at any
  62   // one time.  This value should be based on the logical capacity of the
  63   // capture pipeline, and not on hardware performance.  For example, tab
  64   // capture requires more buffers than webcam capture because the pipeline is
  65   // longer (it includes read-backs pending in the GPU pipeline).
  66   explicit VideoCaptureController(int max_buffers);
  67   virtual ~VideoCaptureController();
  68
  69   base::WeakPtr<VideoCaptureController> GetWeakPtrForIOThread();
  70
  71   // Return a new VideoCaptureDeviceClient to forward capture events to this
  72   // instance. Some device clients need to allocate resources for the given
  73   // capture |format| and/or work on Capture Thread (|capture_task_runner|).
  74   scoped_ptr<media::VideoCaptureDevice::Client> NewDeviceClient(
  75       const scoped_refptr<base::SingleThreadTaskRunner>& capture_task_runner,
  76       const media::VideoCaptureFormat& format);
  77
  78   // Start video capturing and try to use the resolution specified in |params|.
  79   // Buffers will be shared to the client as necessary. The client will continue
  80   // to receive frames from the device until RemoveClient() is called.
  81   void AddClient(VideoCaptureControllerID id,
  82                  VideoCaptureControllerEventHandler* event_handler,
  83                  base::ProcessHandle render_process,
  84                  media::VideoCaptureSessionId session_id,
  85                  const media::VideoCaptureParams& params);
  86
  87   // Stop video capture. This will take back all buffers held by by
  88   // |event_handler|, and |event_handler| shouldn't use those buffers any more.
  89   // Returns the session_id of the stopped client, or
  90   // kInvalidMediaCaptureSessionId if the indicated client was not registered.
  91   int RemoveClient(VideoCaptureControllerID id,
  92                    VideoCaptureControllerEventHandler* event_handler);
  93
  94   // Pause or resume the video capture for specified client.
  95   void PauseOrResumeClient(VideoCaptureControllerID id,
  96                            VideoCaptureControllerEventHandler* event_handler,
  97                            bool pause);
  98
  99   int GetClientCount() const;
 100
 101   // Return the number of clients that aren't paused.
 102   int GetActiveClientCount() const;
 103
 104   // API called directly by VideoCaptureManager in case the device is
 105   // prematurely closed.
 106   void StopSession(int session_id);
 107
 108   // Return a buffer with id |buffer_id| previously given in
 109   // VideoCaptureControllerEventHandler::OnBufferReady. In the case that the
 110   // buffer was backed by a texture, |sync_point| will be waited on before
 111   // destroying or recycling the texture, to synchronize with texture users in
 112   // the renderer process.
 113   void ReturnBuffer(VideoCaptureControllerID id,
 114                     VideoCaptureControllerEventHandler* event_handler,
 115                     int buffer_id,
 116                     uint32 sync_point);
 117
 118   const media::VideoCaptureFormat& GetVideoCaptureFormat() const;
 119
 120   bool has_received_frames() const { return has_received_frames_; }
 121
 122   // Worker functions on IO thread. Called by the VideoCaptureDeviceClient.
 123   void DoIncomingCapturedVideoFrameOnIOThread(
 124       const scoped_refptr<media::VideoCaptureDevice::Client::Buffer>& buffer,
 125       const scoped_refptr<media::VideoFrame>& frame,
 126       const base::TimeTicks& timestamp);
 127   void DoErrorOnIOThread();
 128   void DoLogOnIOThread(const std::string& message);
 129   void DoBufferDestroyedOnIOThread(int buffer_id_to_drop);
 130
 131  private:
 132   struct ControllerClient;
 133   typedef std::list<ControllerClient*> ControllerClients;
 134
 135   // Find a client of |id| and |handler| in |clients|.
 136   ControllerClient* FindClient(VideoCaptureControllerID id,
 137                                VideoCaptureControllerEventHandler* handler,
 138                                const ControllerClients& clients);
 139
 140   // Find a client of |session_id| in |clients|.
 141   ControllerClient* FindClient(int session_id,
 142                                const ControllerClients& clients);
 143
 144   // The pool of shared-memory buffers used for capturing.
 145   const scoped_refptr<VideoCaptureBufferPool> buffer_pool_;
 146
 147   // All clients served by this controller.
 148   ControllerClients controller_clients_;
 149
 150   // Takes on only the states 'STARTED' and 'ERROR'. 'ERROR' is an absorbing
 151   // state which stops the flow of data to clients.
 152   VideoCaptureState state_;
 153
 154   // True if the controller has received a video frame from the device.
 155   bool has_received_frames_;
 156
 157   media::VideoCaptureFormat video_capture_format_;
 158
 159   base::WeakPtrFactory<VideoCaptureController> weak_ptr_factory_;
 160
 161   DISALLOW_COPY_AND_ASSIGN(VideoCaptureController);
 162 };
 163
 164 }  // namespace content
 165
 166 #endif  // CONTENT_BROWSER_RENDERER_HOST_MEDIA_VIDEO_CAPTURE_CONTROLLER_H_