media/capture/video/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/capture/video/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   ~FileVideoCaptureDevice() override;
  39   void AllocateAndStart(const VideoCaptureParams& params,
  40                         scoped_ptr<VideoCaptureDevice::Client> client) override;
  41   void StopAndDeAllocate() override;
  42
  43  private:
  44   // Returns size in bytes of an I420 frame, not including possible paddings,
  45   // defined by |capture_format_|.
  46   int CalculateFrameSize() const;
  47
  48   // Called on the |capture_thread_|.
  49   void OnAllocateAndStart(const VideoCaptureParams& params,
  50                           scoped_ptr<Client> client);
  51   void OnStopAndDeAllocate();
  52   void OnCaptureTask();
  53
  54   // |thread_checker_| is used to check that destructor, AllocateAndStart() and
  55   // StopAndDeAllocate() are called in the correct thread that owns the object.
  56   base::ThreadChecker thread_checker_;
  57
  58   // |capture_thread_| is used for internal operations via posting tasks to it.
  59   // It is active between OnAllocateAndStart() and OnStopAndDeAllocate().
  60   base::Thread capture_thread_;
  61   // The following members belong to |capture_thread_|.
  62   scoped_ptr<VideoCaptureDevice::Client> client_;
  63   const base::FilePath file_path_;
  64   base::File file_;
  65   scoped_ptr<uint8[]> video_frame_;
  66   VideoCaptureFormat capture_format_;
  67   int frame_size_;
  68   int64 current_byte_index_;
  69   int64 first_frame_byte_index_;
  70   // Target time for the next frame.
  71   base::TimeTicks next_frame_time_;
  72
  73   DISALLOW_COPY_AND_ASSIGN(FileVideoCaptureDevice);
  74 };
  75
  76 }  // namespace media
  77
  78 #endif  // MEDIA_VIDEO_CAPTURE_FILE_VIDEO_CAPTURE_DEVICE_H_