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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/files/file.h"
     11 #include "base/memory/scoped_ptr.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   static int64 ParseFileAndExtractVideoFormat(
     29       base::File* file,
     30       media::VideoCaptureFormat* video_format);
     31   static base::File OpenFileForRead(const base::FilePath& file_path);
     32 
     33   // Constructor of the class, with a fully qualified file path as input, which
     34   // represents the Y4M video file to stream repeatedly.
     35   explicit FileVideoCaptureDevice(const base::FilePath& file_path);
     36 
     37   // VideoCaptureDevice implementation, class methods.
     38   virtual ~FileVideoCaptureDevice();
     39   virtual void AllocateAndStart(
     40       const VideoCaptureParams& params,
     41       scoped_ptr<VideoCaptureDevice::Client> client) OVERRIDE;
     42   virtual void StopAndDeAllocate() OVERRIDE;
     43 
     44  private:
     45   // Returns size in bytes of an I420 frame, not including possible paddings,
     46   // defined by |capture_format_|.
     47   int CalculateFrameSize();
     48 
     49   // Called on the |capture_thread_|.
     50   void OnAllocateAndStart(const VideoCaptureParams& params,
     51                           scoped_ptr<Client> client);
     52   void OnStopAndDeAllocate();
     53   void OnCaptureTask();
     54 
     55   // |thread_checker_| is used to check that destructor, AllocateAndStart() and
     56   // StopAndDeAllocate() are called in the correct thread that owns the object.
     57   base::ThreadChecker thread_checker_;
     58 
     59   // |capture_thread_| is used for internal operations via posting tasks to it.
     60   // It is active between OnAllocateAndStart() and OnStopAndDeAllocate().
     61   base::Thread capture_thread_;
     62   // The following members belong to |capture_thread_|.
     63   scoped_ptr<VideoCaptureDevice::Client> client_;
     64   const base::FilePath file_path_;
     65   base::File file_;
     66   scoped_ptr<uint8[]> video_frame_;
     67   VideoCaptureFormat capture_format_;
     68   int frame_size_;
     69   int64 current_byte_index_;
     70   int64 first_frame_byte_index_;
     71 
     72   DISALLOW_COPY_AND_ASSIGN(FileVideoCaptureDevice);
     73 };
     74 
     75 }  // namespace media
     76 
     77 #endif  // MEDIA_VIDEO_CAPTURE_FILE_VIDEO_CAPTURE_DEVICE_H_
     78