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 H264_DPB_H_ 9 #define H264_DPB_H_ 10 11 #include <stddef.h> 12 13 #include <vector> 14 15 #include "base/macros.h" 16 #include "base/memory/ref_counted.h" 17 #include "h264_parser.h" 18 19 namespace media { 20 21 class V4L2H264Picture; 22 23 // A picture (a frame or a field) in the H.264 spec sense. 24 // See spec at http://www.itu.int/rec/T-REC-H.264 25 class H264Picture : public base::RefCounted<H264Picture> { 26 public: 27 using Vector = std::vector<scoped_refptr<H264Picture>>; 28 29 enum Field { 30 FIELD_NONE, 31 FIELD_TOP, 32 FIELD_BOTTOM, 33 }; 34 35 H264Picture(); 36 37 virtual V4L2H264Picture* AsV4L2H264Picture(); 38 39 // Values calculated per H.264 specification or taken from slice header. 40 // See spec for more details on each (some names have been converted from 41 // CamelCase in spec to Chromium-style names). 42 int pic_order_cnt_type; 43 int top_field_order_cnt; 44 int bottom_field_order_cnt; 45 int pic_order_cnt; 46 int pic_order_cnt_msb; 47 int pic_order_cnt_lsb; 48 int delta_pic_order_cnt_bottom; 49 int delta_pic_order_cnt0; 50 int delta_pic_order_cnt1; 51 52 int pic_num; 53 int long_term_pic_num; 54 int frame_num; // from slice header 55 int frame_num_offset; 56 int frame_num_wrap; 57 int long_term_frame_idx; 58 59 H264SliceHeader::Type type; 60 int nal_ref_idc; 61 bool idr; // IDR picture? 62 int idr_pic_id; // Valid only if idr == true. 63 bool ref; // reference picture? 64 bool long_term; // long term reference picture? 65 bool outputted; 66 // Does memory management op 5 needs to be executed after this 67 // picture has finished decoding? 68 bool mem_mgmt_5; 69 70 // Created by the decoding process for gaps in frame_num. 71 // Not for decode or output. 72 bool nonexisting; 73 74 Field field; 75 76 // Values from slice_hdr to be used during reference marking and 77 // memory management after finishing this picture. 78 bool long_term_reference_flag; 79 bool adaptive_ref_pic_marking_mode_flag; 80 H264DecRefPicMarking ref_pic_marking[H264SliceHeader::kRefListSize]; 81 82 // Position in DPB (i.e. index in DPB). 83 int dpb_position; 84 85 protected: 86 friend class base::RefCounted<H264Picture>; 87 virtual ~H264Picture(); 88 89 private: 90 DISALLOW_COPY_AND_ASSIGN(H264Picture); 91 }; 92 93 // DPB - Decoded Picture Buffer. 94 // Stores decoded pictures that will be used for future display 95 // and/or reference. 96 class H264DPB { 97 public: 98 H264DPB(); 99 ~H264DPB(); 100 101 void set_max_num_pics(size_t max_num_pics); 102 size_t max_num_pics() const { return max_num_pics_; } 103 104 // Remove unused (not reference and already outputted) pictures from DPB 105 // and free it. 106 void DeleteUnused(); 107 108 // Remove a picture by its pic_order_cnt and free it. 109 void DeleteByPOC(int poc); 110 111 // Clear DPB. 112 void Clear(); 113 114 // Store picture in DPB. DPB takes ownership of its resources. 115 void StorePic(const scoped_refptr<H264Picture>& pic); 116 117 // Return the number of reference pictures in DPB. 118 int CountRefPics(); 119 120 // Mark all pictures in DPB as unused for reference. 121 void MarkAllUnusedForRef(); 122 123 // Return a short-term reference picture by its pic_num. 124 scoped_refptr<H264Picture> GetShortRefPicByPicNum(int pic_num); 125 126 // Return a long-term reference picture by its long_term_pic_num. 127 scoped_refptr<H264Picture> GetLongRefPicByLongTermPicNum(int pic_num); 128 129 // Return the short reference picture with lowest frame_num. Used for sliding 130 // window memory management. 131 scoped_refptr<H264Picture> GetLowestFrameNumWrapShortRefPic(); 132 133 // Append all pictures that have not been outputted yet to the passed |out| 134 // vector, sorted by lowest pic_order_cnt (in output order). 135 void GetNotOutputtedPicsAppending(H264Picture::Vector* out); 136 137 // Append all short term reference pictures to the passed |out| vector. 138 void GetShortTermRefPicsAppending(H264Picture::Vector* out); 139 140 // Append all long term reference pictures to the passed |out| vector. 141 void GetLongTermRefPicsAppending(H264Picture::Vector* out); 142 143 // Iterators for direct access to DPB contents. 144 // Will be invalidated after any of Remove* calls. 145 H264Picture::Vector::iterator begin() { return pics_.begin(); } 146 H264Picture::Vector::iterator end() { return pics_.end(); } 147 H264Picture::Vector::const_iterator begin() const { return pics_.begin(); } 148 H264Picture::Vector::const_iterator end() const { return pics_.end(); } 149 H264Picture::Vector::const_reverse_iterator rbegin() const { 150 return pics_.rbegin(); 151 } 152 H264Picture::Vector::const_reverse_iterator rend() const { 153 return pics_.rend(); 154 } 155 156 size_t size() const { return pics_.size(); } 157 bool IsFull() const { return pics_.size() == max_num_pics_; } 158 159 // Per H264 spec, increase to 32 if interlaced video is supported. 160 enum { 161 kDPBMaxSize = 16, 162 }; 163 164 private: 165 void UpdatePicPositions(); 166 167 H264Picture::Vector pics_; 168 size_t max_num_pics_; 169 170 DISALLOW_COPY_AND_ASSIGN(H264DPB); 171 }; 172 173 } // namespace media 174 175 #endif // H264_DPB_H_ 176
