1// Copyright (c) 2012 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// This file contains an implementation of an H.264 Decoded Picture Buffer
6// used in H264 decoders.
7
8#ifndef CONTENT_COMMON_GPU_MEDIA_H264_DPB_H_
9#define CONTENT_COMMON_GPU_MEDIA_H264_DPB_H_
10
11#include <vector>
12
13#include "base/basictypes.h"
14#include "base/memory/scoped_vector.h"
15#include "media/filters/h264_parser.h"
16
17namespace content {
18
19// A picture (a frame or a field) in the H.264 spec sense.
20// See spec at http://www.itu.int/rec/T-REC-H.264
21struct H264Picture {
22  enum Field {
23    FIELD_NONE,
24    FIELD_TOP,
25    FIELD_BOTTOM,
26  };
27
28  // Values calculated per H.264 specification or taken from slice header.
29  // See spec for more details on each (some names have been converted from
30  // CamelCase in spec to Chromium-style names).
31  int top_field_order_cnt;
32  int bottom_field_order_cnt;
33  int pic_order_cnt;
34  int pic_order_cnt_msb;
35  int pic_order_cnt_lsb;
36
37  int pic_num;
38  int long_term_pic_num;
39  int frame_num;  // from slice header
40  int frame_num_offset;
41  int frame_num_wrap;
42  int long_term_frame_idx;
43
44  media::H264SliceHeader::Type type;
45  bool idr;  // IDR picture?
46  bool ref;  // reference picture?
47  bool long_term;  // long term reference picture?
48  bool outputted;
49  // Does memory management op 5 needs to be executed after this
50  // picture has finished decoding?
51  bool mem_mgmt_5;
52
53  Field field;
54
55  // Values from slice_hdr to be used during reference marking and
56  // memory management after finishing this picture.
57  bool long_term_reference_flag;
58  bool adaptive_ref_pic_marking_mode_flag;
59  media::H264DecRefPicMarking
60      ref_pic_marking[media::H264SliceHeader::kRefListSize];
61
62  typedef std::vector<H264Picture*> PtrVector;
63};
64
65// DPB - Decoded Picture Buffer.
66// Stores decoded pictures that will be used for future display
67// and/or reference.
68class H264DPB {
69 public:
70  H264DPB();
71  ~H264DPB();
72
73  void set_max_num_pics(size_t max_num_pics);
74  size_t max_num_pics() { return max_num_pics_; }
75
76  // Remove unused (not reference and already outputted) pictures from DPB
77  // and free it.
78  void DeleteUnused();
79
80  // Remove a picture by its pic_order_cnt and free it.
81  void DeleteByPOC(int poc);
82
83  // Clear DPB.
84  void Clear();
85
86  // Store picture in DPB. DPB takes ownership of its resources.
87  void StorePic(H264Picture* pic);
88
89  // Return the number of reference pictures in DPB.
90  int CountRefPics();
91
92  // Mark all pictures in DPB as unused for reference.
93  void MarkAllUnusedForRef();
94
95  // Return a short-term reference picture by its pic_num.
96  H264Picture* GetShortRefPicByPicNum(int pic_num);
97
98  // Return a long-term reference picture by its long_term_pic_num.
99  H264Picture* GetLongRefPicByLongTermPicNum(int pic_num);
100
101  // Return the short reference picture with lowest frame_num. Used for sliding
102  // window memory management.
103  H264Picture* GetLowestFrameNumWrapShortRefPic();
104
105  // Append all pictures that have not been outputted yet to the passed |out|
106  // vector, sorted by lowest pic_order_cnt (in output order).
107  void GetNotOutputtedPicsAppending(H264Picture::PtrVector& out);
108
109  // Append all short term reference pictures to the passed |out| vector.
110  void GetShortTermRefPicsAppending(H264Picture::PtrVector& out);
111
112  // Append all long term reference pictures to the passed |out| vector.
113  void GetLongTermRefPicsAppending(H264Picture::PtrVector& out);
114
115  // Iterators for direct access to DPB contents.
116  // Will be invalidated after any of Remove* calls.
117  typedef ScopedVector<H264Picture> Pictures;
118  Pictures::iterator begin() { return pics_.begin(); }
119  Pictures::iterator end() { return pics_.end(); }
120  Pictures::reverse_iterator rbegin() { return pics_.rbegin(); }
121  Pictures::reverse_iterator rend() { return pics_.rend(); }
122
123  size_t size() const { return pics_.size(); }
124  bool IsFull() const { return pics_.size() == max_num_pics_; }
125
126  // Per H264 spec, increase to 32 if interlaced video is supported.
127  enum { kDPBMaxSize = 16, };
128
129 private:
130  Pictures pics_;
131  size_t max_num_pics_;
132
133  DISALLOW_COPY_AND_ASSIGN(H264DPB);
134};
135
136}  // namespace content
137
138#endif  // CONTENT_COMMON_GPU_MEDIA_H264_DPB_H_
139