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// Copyright (c) 2011 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.
// Linux specific implementation of VideoCaptureDevice.
// V4L2 is used for capturing. V4L2 does not provide it's own thread for
// capturing so this implementation uses a Chromium thread for fetching frames
// from V4L2.
#ifndef MEDIA_VIDEO_CAPTURE_LINUX_VIDEO_CAPTURE_DEVICE_LINUX_H_
#define MEDIA_VIDEO_CAPTURE_LINUX_VIDEO_CAPTURE_DEVICE_LINUX_H_
#include <string>
#include "base/threading/thread.h"
#include "media/video/capture/video_capture_device.h"
namespace media {
class VideoCaptureDeviceLinux : public VideoCaptureDevice {
public:
explicit VideoCaptureDeviceLinux(const Name& device_name);
virtual ~VideoCaptureDeviceLinux();
// VideoCaptureDevice implementation.
virtual void Allocate(int width,
int height,
int frame_rate,
EventHandler* observer) OVERRIDE;
virtual void Start() OVERRIDE;
virtual void Stop() OVERRIDE;
virtual void DeAllocate() OVERRIDE;
virtual const Name& device_name() OVERRIDE;
private:
enum InternalState {
kIdle, // The device driver is opened but camera is not in use.
kAllocated, // The camera has been allocated and can be started.
kCapturing, // Video is being captured.
kError // Error accessing HW functions.
// User needs to recover by destroying the object.
};
// Buffers used to receive video frames from with v4l2.
struct Buffer {
Buffer() : start(0), length(0) {}
void* start;
size_t length;
};
// Called on the v4l2_thread_.
void OnAllocate(int width,
int height,
int frame_rate,
EventHandler* observer);
void OnStart();
void OnStop();
void OnDeAllocate();
void OnCaptureTask();
bool AllocateVideoBuffers();
void DeAllocateVideoBuffers();
void SetErrorState(const std::string& reason);
InternalState state_;
VideoCaptureDevice::EventHandler* observer_;
Name device_name_;
int device_fd_; // File descriptor for the opened camera device.
base::Thread v4l2_thread_; // Thread used for reading data from the device.
Buffer* buffer_pool_;
int buffer_pool_size_; // Number of allocated buffers.
DISALLOW_IMPLICIT_CONSTRUCTORS(VideoCaptureDeviceLinux);
};
} // namespace media
DISABLE_RUNNABLE_METHOD_REFCOUNT(media::VideoCaptureDeviceLinux);
#endif // MEDIA_VIDEO_CAPTURE_LINUX_VIDEO_CAPTURE_DEVICE_LINUX_H_
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