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
16namespace 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.
26class 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