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 // A helper class, VCC::VideoCaptureDeviceClient, is responsible for:
  23 //
  24 //   * Conveying events from the device thread (where VideoCaptureDevices live)
  25 //     the IO thread (where the VideoCaptureController lives).
  26 //   * Performing some image transformations on the output of the Device;
  27 //     specifically, colorspace conversion and rotation.
  28 //
  29 // Interactions between VideoCaptureController and other classes:
  30 //
  31 //   * VideoCaptureController indirectly observes a VideoCaptureDevice
  32 //     by means of its proxy, VideoCaptureDeviceClient, which implements
  33 //     the VideoCaptureDevice::Client interface. The proxy forwards
  34 //     observed events to the VideoCaptureController on the IO thread.
  35 //   * A VideoCaptureController interacts with its clients (VideoCaptureHosts)
  36 //     via the VideoCaptureControllerEventHandler interface.
  37 //   * Conversely, a VideoCaptureControllerEventHandler (typically,
  38 //     VideoCaptureHost) will interact directly with VideoCaptureController to
  39 //     return leased buffers by means of the ReturnBuffer() public method of
  40 //     VCC.
  41 //   * VideoCaptureManager (which owns the VCC) interacts directly with
  42 //     VideoCaptureController through its public methods, to add and remove
  43 //     clients.
  44 //
  45 // VideoCaptureController is not thread safe and operates on the IO thread only.
  46
  47 #ifndef CONTENT_BROWSER_RENDERER_HOST_MEDIA_VIDEO_CAPTURE_CONTROLLER_H_
  48 #define CONTENT_BROWSER_RENDERER_HOST_MEDIA_VIDEO_CAPTURE_CONTROLLER_H_
  49
  50 #include <list>
  51
  52 #include "base/compiler_specific.h"
  53 #include "base/memory/ref_counted.h"
  54 #include "base/memory/scoped_ptr.h"
  55 #include "base/memory/weak_ptr.h"
  56 #include "base/process/process.h"
  57 #include "content/browser/renderer_host/media/video_capture_buffer_pool.h"
  58 #include "content/browser/renderer_host/media/video_capture_controller_event_handler.h"
  59 #include "content/common/content_export.h"
  60 #include "content/common/media/video_capture.h"
  61 #include "media/video/capture/video_capture_device.h"
  62 #include "media/video/capture/video_capture_types.h"
  63
  64 namespace content {
  65 class VideoCaptureBufferPool;
  66
  67 class CONTENT_EXPORT VideoCaptureController {
  68  public:
  69   // |max_buffers| is the maximum number of video frame buffers in-flight at any
  70   // one time.  This value should be based on the logical capacity of the
  71   // capture pipeline, and not on hardware performance.  For example, tab
  72   // capture requires more buffers than webcam capture because the pipeline is
  73   // longer (it includes read-backs pending in the GPU pipeline).
  74   explicit VideoCaptureController(int max_buffers);
  75   virtual ~VideoCaptureController();
  76
  77   base::WeakPtr<VideoCaptureController> GetWeakPtr();
  78
  79   // Return a new VideoCaptureDeviceClient to forward capture events to this
  80   // instance.
  81   scoped_ptr<media::VideoCaptureDevice::Client> NewDeviceClient();
  82
  83   // Start video capturing and try to use the resolution specified in |params|.
  84   // Buffers will be shared to the client as necessary. The client will continue
  85   // to receive frames from the device until RemoveClient() is called.
  86   void AddClient(const VideoCaptureControllerID& id,
  87                  VideoCaptureControllerEventHandler* event_handler,
  88                  base::ProcessHandle render_process,
  89                  media::VideoCaptureSessionId session_id,
  90                  const media::VideoCaptureParams& params);
  91
  92   // Stop video capture. This will take back all buffers held by by
  93   // |event_handler|, and |event_handler| shouldn't use those buffers any more.
  94   // Returns the session_id of the stopped client, or
  95   // kInvalidMediaCaptureSessionId if the indicated client was not registered.
  96   int RemoveClient(const VideoCaptureControllerID& id,
  97                    VideoCaptureControllerEventHandler* event_handler);
  98
  99   int GetClientCount();
 100
 101   // API called directly by VideoCaptureManager in case the device is
 102   // prematurely closed.
 103   void StopSession(int session_id);
 104
 105   // Return a buffer with id |buffer_id| previously given in
 106   // VideoCaptureControllerEventHandler::OnBufferReady. In the case that the
 107   // buffer was backed by a texture, |sync_point| will be waited on before
 108   // destroying or recycling the texture, to synchronize with texture users in
 109   // the renderer process.
 110   void ReturnBuffer(const VideoCaptureControllerID& id,
 111                     VideoCaptureControllerEventHandler* event_handler,
 112                     int buffer_id,
 113                     uint32 sync_point);
 114
 115   const media::VideoCaptureFormat& GetVideoCaptureFormat() const;
 116
 117  private:
 118   class VideoCaptureDeviceClient;
 119
 120   struct ControllerClient;
 121   typedef std::list<ControllerClient*> ControllerClients;
 122
 123   // Worker functions on IO thread. Called by the VideoCaptureDeviceClient.
 124   void DoIncomingCapturedVideoFrameOnIOThread(
 125       const scoped_refptr<media::VideoCaptureDevice::Client::Buffer>& buffer,
 126       const media::VideoCaptureFormat& format,
 127       const scoped_refptr<media::VideoFrame>& frame,
 128       base::TimeTicks timestamp);
 129   void DoErrorOnIOThread();
 130   void DoDeviceStoppedOnIOThread();
 131   void DoBufferDestroyedOnIOThread(int buffer_id_to_drop);
 132
 133   // Find a client of |id| and |handler| in |clients|.
 134   ControllerClient* FindClient(
 135       const VideoCaptureControllerID& id,
 136       VideoCaptureControllerEventHandler* handler,
 137       const ControllerClients& clients);
 138
 139   // Find a client of |session_id| in |clients|.
 140   ControllerClient* FindClient(
 141       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   media::VideoCaptureFormat video_capture_format_;
 155
 156   base::WeakPtrFactory<VideoCaptureController> weak_ptr_factory_;
 157
 158   DISALLOW_COPY_AND_ASSIGN(VideoCaptureController);
 159 };
 160
 161 }  // namespace content
 162
 163 #endif  // CONTENT_BROWSER_RENDERER_HOST_MEDIA_VIDEO_CAPTURE_CONTROLLER_H_