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/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_