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      1 // Copyright 2013 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 #ifndef MEDIA_VIDEO_CAPTURE_FILE_VIDEO_CAPTURE_DEVICE_H_
      6 #define MEDIA_VIDEO_CAPTURE_FILE_VIDEO_CAPTURE_DEVICE_H_
      7 
      8 #include <string>
      9 
     10 #include "base/memory/scoped_ptr.h"
     11 #include "base/platform_file.h"
     12 #include "base/threading/thread.h"
     13 #include "base/threading/thread_checker.h"
     14 #include "media/video/capture/video_capture_device.h"
     15 
     16 namespace media {
     17 
     18 // Implementation of a VideoCaptureDevice class that reads from a file. Used for
     19 // testing the video capture pipeline when no real hardware is available. The
     20 // only supported file format is YUV4MPEG2 (a.k.a. Y4M), a minimal container
     21 // with a series of uncompressed video only frames, see the link
     22 // http://wiki.multimedia.cx/index.php?title=YUV4MPEG2 for more information
     23 // on the file format. Several restrictions and notes apply, see the
     24 // implementation file.
     25 // Example videos can be found in http://media.xiph.org/video/derf.
     26 class MEDIA_EXPORT FileVideoCaptureDevice : public VideoCaptureDevice {
     27  public:
     28   // VideoCaptureDevice implementation, static methods. Create() returns a
     29   // pointer to the object, fully owned by the caller.
     30   // TODO(mcasas): Create() should return a scoped_ptr<> http://crbug.com/321613
     31   static VideoCaptureDevice* Create(const Name& device_name);
     32   static void GetDeviceNames(Names* device_names);
     33   static void GetDeviceSupportedFormats(const Name& device,
     34                                         VideoCaptureFormats* supported_formats);
     35 
     36   // VideoCaptureDevice implementation, class methods.
     37   virtual ~FileVideoCaptureDevice();
     38   virtual void AllocateAndStart(
     39       const VideoCaptureParams& params,
     40       scoped_ptr<VideoCaptureDevice::Client> client) OVERRIDE;
     41   virtual void StopAndDeAllocate() OVERRIDE;
     42 
     43  private:
     44   // Constructor of the class, with a fully qualified file path as input, which
     45   // represents the Y4M video file to stream repeatedly.
     46   explicit FileVideoCaptureDevice(const base::FilePath& file_path);
     47   // Returns size in bytes of an I420 frame, not including possible paddings,
     48   // defined by |capture_format_|.
     49   int CalculateFrameSize();
     50 
     51   // Called on the |capture_thread_|.
     52   void OnAllocateAndStart(const VideoCaptureParams& params,
     53                           scoped_ptr<Client> client);
     54   void OnStopAndDeAllocate();
     55   void OnCaptureTask();
     56 
     57   // |thread_checker_| is used to check that destructor, AllocateAndStart() and
     58   // StopAndDeAllocate() are called in the correct thread that owns the object.
     59   base::ThreadChecker thread_checker_;
     60 
     61   // |capture_thread_| is used for internal operations via posting tasks to it.
     62   // It is active between OnAllocateAndStart() and OnStopAndDeAllocate().
     63   base::Thread capture_thread_;
     64   // The following members belong to |capture_thread_|.
     65   scoped_ptr<VideoCaptureDevice::Client> client_;
     66   const base::FilePath file_path_;
     67   base::PlatformFile file_;
     68   scoped_ptr<uint8[]> video_frame_;
     69   VideoCaptureFormat capture_format_;
     70   int frame_size_;
     71   int64 current_byte_index_;
     72   int64 first_frame_byte_index_;
     73 
     74   DISALLOW_COPY_AND_ASSIGN(FileVideoCaptureDevice);
     75 };
     76 
     77 }  // namespace media
     78 
     79 #endif  // MEDIA_VIDEO_CAPTURE_FILE_VIDEO_CAPTURE_DEVICE_H_
     80