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// 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.
//
// VideoCaptureDevice is the abstract base class for realizing video capture
// device support in Chromium. It provides the interface for OS dependent
// implementations.
// The class is created and functions are invoked on a thread owned by
// VideoCaptureManager. Capturing is done on other threads depended on the OS
// specific implementation.
#ifndef MEDIA_VIDEO_CAPTURE_VIDEO_CAPTURE_DEVICE_H_
#define MEDIA_VIDEO_CAPTURE_VIDEO_CAPTURE_DEVICE_H_
#include <list>
#include <string>
#include "base/time.h"
#include "media/base/media_export.h"
#include "media/video/capture/video_capture_types.h"
namespace media {
class MEDIA_EXPORT VideoCaptureDevice {
public:
struct Name {
// Friendly name of a device
std::string device_name;
// Unique name of a device. Even if there are multiple devices with the same
// friendly name connected to the computer this will be unique.
std::string unique_id;
};
typedef std::list<Name> Names;
class MEDIA_EXPORT EventHandler {
public:
// Captured a new video frame as a raw buffer. The size, color format, and
// layout are taken from the parameters specified by an earlier call to
// OnFrameInfo(). |data| must be packed, with no padding between rows and/or
// color planes.
virtual void OnIncomingCapturedFrame(const uint8* data,
int length,
base::Time timestamp) = 0;
// Captured a new video frame, held in a VideoFrame container. |frame| must
// be allocated as RGB32, YV12 or I420, and the size must match that
// specified by an earlier call to OnFrameInfo().
virtual void OnIncomingCapturedVideoFrame(media::VideoFrame* frame,
base::Time timestamp) = 0;
// An error has occurred that cannot be handled and VideoCaptureDevice must
// be DeAllocate()-ed.
virtual void OnError() = 0;
// Called when VideoCaptureDevice::Allocate() has been called to inform of
// the resulting frame size.
virtual void OnFrameInfo(const VideoCaptureCapability& info) = 0;
protected:
virtual ~EventHandler() {}
};
// Creates a VideoCaptureDevice object.
// Return NULL if the hardware is not available.
static VideoCaptureDevice* Create(const Name& device_name);
virtual ~VideoCaptureDevice() {}
// Gets the names of all video capture devices connected to this computer.
static void GetDeviceNames(Names* device_names);
// Prepare the camera for use. After this function has been called no other
// applications can use the camera. On completion EventHandler::OnFrameInfo()
// is called informing of the resulting resolution and frame rate.
// DeAllocate() must be called before this function can be called again and
// before the object is deleted.
virtual void Allocate(int width,
int height,
int frame_rate,
EventHandler* observer) = 0;
// Start capturing video frames. Allocate must be called before this function.
virtual void Start() = 0;
// Stop capturing video frames.
virtual void Stop() = 0;
// Deallocates the camera. This means other applications can use it. After
// this function has been called the capture device is reset to the state it
// was when created.
virtual void DeAllocate() = 0;
// Get the name of the capture device.
virtual const Name& device_name() = 0;
};
} // namespace media
#endif // MEDIA_VIDEO_CAPTURE_VIDEO_CAPTURE_DEVICE_H_
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