// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//
// VideoCaptureController is the glue between a VideoCaptureDevice and all
// VideoCaptureHosts that have connected to it. A controller exists on behalf of
// one (and only one) VideoCaptureDevice; both are owned by the
// VideoCaptureManager.
//
// The VideoCaptureController is responsible for:
//
// * Allocating and keeping track of shared memory buffers, and filling them
// with I420 video frames for IPC communication between VideoCaptureHost (in
// the browser process) and VideoCaptureMessageFilter (in the renderer
// process).
// * Broadcasting the events from a single VideoCaptureDevice, fanning them
// out to multiple clients.
// * Keeping track of the clients on behalf of the VideoCaptureManager, making
// it possible for the Manager to delete the Controller and its Device when
// there are no clients left.
//
// A helper class, VCC::VideoCaptureDeviceClient, is responsible for:
//
// * Conveying events from the device thread (where VideoCaptureDevices live)
// the IO thread (where the VideoCaptureController lives).
// * Performing some image transformations on the output of the Device;
// specifically, colorspace conversion and rotation.
//
// Interactions between VideoCaptureController and other classes:
//
// * VideoCaptureController indirectly observes a VideoCaptureDevice
// by means of its proxy, VideoCaptureDeviceClient, which implements
// the VideoCaptureDevice::Client interface. The proxy forwards
// observed events to the VideoCaptureController on the IO thread.
// * A VideoCaptureController interacts with its clients (VideoCaptureHosts)
// via the VideoCaptureControllerEventHandler interface.
// * Conversely, a VideoCaptureControllerEventHandler (typically,
// VideoCaptureHost) will interact directly with VideoCaptureController to
// return leased buffers by means of the ReturnBuffer() public method of
// VCC.
// * VideoCaptureManager (which owns the VCC) interacts directly with
// VideoCaptureController through its public methods, to add and remove
// clients.
//
// VideoCaptureController is not thread safe and operates on the IO thread only.
#ifndef CONTENT_BROWSER_RENDERER_HOST_MEDIA_VIDEO_CAPTURE_CONTROLLER_H_
#define CONTENT_BROWSER_RENDERER_HOST_MEDIA_VIDEO_CAPTURE_CONTROLLER_H_
#include <list>
#include "base/compiler_specific.h"
#include "base/memory/ref_counted.h"
#include "base/memory/scoped_ptr.h"
#include "base/memory/weak_ptr.h"
#include "base/process/process.h"
#include "content/browser/renderer_host/media/video_capture_buffer_pool.h"
#include "content/browser/renderer_host/media/video_capture_controller_event_handler.h"
#include "content/common/content_export.h"
#include "content/common/media/video_capture.h"
#include "media/video/capture/video_capture.h"
#include "media/video/capture/video_capture_device.h"
#include "media/video/capture/video_capture_types.h"
namespace content {
class VideoCaptureBufferPool;
class CONTENT_EXPORT VideoCaptureController {
public:
VideoCaptureController();
virtual ~VideoCaptureController();
base::WeakPtr<VideoCaptureController> GetWeakPtr();
// Return a new VideoCaptureDeviceClient to forward capture events to this
// instance.
scoped_ptr<media::VideoCaptureDevice::Client> NewDeviceClient();
// Start video capturing and try to use the resolution specified in |params|.
// Buffers will be shared to the client as necessary. The client will continue
// to receive frames from the device until RemoveClient() is called.
void AddClient(const VideoCaptureControllerID& id,
VideoCaptureControllerEventHandler* event_handler,
base::ProcessHandle render_process,
media::VideoCaptureSessionId session_id,
const media::VideoCaptureParams& params);
// Stop video capture. This will take back all buffers held by by
// |event_handler|, and |event_handler| shouldn't use those buffers any more.
// Returns the session_id of the stopped client, or
// kInvalidMediaCaptureSessionId if the indicated client was not registered.
int RemoveClient(const VideoCaptureControllerID& id,
VideoCaptureControllerEventHandler* event_handler);
int GetClientCount();
// API called directly by VideoCaptureManager in case the device is
// prematurely closed.
void StopSession(int session_id);
// Return a buffer with id |buffer_id| previously given in
// VideoCaptureControllerEventHandler::OnBufferReady. In the case that the
// buffer was backed by a texture, |sync_point| will be waited on before
// destroying or recycling the texture, to synchronize with texture users in
// the renderer process.
void ReturnBuffer(const VideoCaptureControllerID& id,
VideoCaptureControllerEventHandler* event_handler,
int buffer_id,
uint32 sync_point);
const media::VideoCaptureFormat& GetVideoCaptureFormat() const;
private:
class VideoCaptureDeviceClient;
struct ControllerClient;
typedef std::list<ControllerClient*> ControllerClients;
// Worker functions on IO thread. Called by the VideoCaptureDeviceClient.
void DoIncomingCapturedVideoFrameOnIOThread(
const scoped_refptr<media::VideoCaptureDevice::Client::Buffer>& buffer,
const media::VideoCaptureFormat& format,
const scoped_refptr<media::VideoFrame>& frame,
base::TimeTicks timestamp);
void DoErrorOnIOThread();
void DoDeviceStoppedOnIOThread();
void DoBufferDestroyedOnIOThread(int buffer_id_to_drop);
// Find a client of |id| and |handler| in |clients|.
ControllerClient* FindClient(
const VideoCaptureControllerID& id,
VideoCaptureControllerEventHandler* handler,
const ControllerClients& clients);
// Find a client of |session_id| in |clients|.
ControllerClient* FindClient(
int session_id,
const ControllerClients& clients);
// The pool of shared-memory buffers used for capturing.
const scoped_refptr<VideoCaptureBufferPool> buffer_pool_;
// All clients served by this controller.
ControllerClients controller_clients_;
// Takes on only the states 'STARTED' and 'ERROR'. 'ERROR' is an absorbing
// state which stops the flow of data to clients.
VideoCaptureState state_;
media::VideoCaptureFormat video_capture_format_;
base::WeakPtrFactory<VideoCaptureController> weak_ptr_factory_;
DISALLOW_COPY_AND_ASSIGN(VideoCaptureController);
};
} // namespace content
#endif // CONTENT_BROWSER_RENDERER_HOST_MEDIA_VIDEO_CAPTURE_CONTROLLER_H_