media/video/capture/file_video_capture_device.h

   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_