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 // Note: ported from Chromium commit head: 70340ce 8 9 #ifndef H264_DPB_H_ 10 #define H264_DPB_H_ 11 12 #include <stddef.h> 13 14 #include <vector> 15 16 #include "base/macros.h" 17 #include "base/memory/ref_counted.h" 18 #include "h264_parser.h" 19 #include "rect.h" 20 21 namespace media { 22 23 class V4L2H264Picture; 24 25 // A picture (a frame or a field) in the H.264 spec sense. 26 // See spec at http://www.itu.int/rec/T-REC-H.264 27 class H264Picture : public base::RefCountedThreadSafe<H264Picture> { 28 public: 29 using Vector = std::vector<scoped_refptr<H264Picture>>; 30 31 enum Field { 32 FIELD_NONE, 33 FIELD_TOP, 34 FIELD_BOTTOM, 35 }; 36 37 H264Picture(); 38 39 virtual V4L2H264Picture* AsV4L2H264Picture(); 40 41 // Values calculated per H.264 specification or taken from slice header. 42 // See spec for more details on each (some names have been converted from 43 // CamelCase in spec to Chromium-style names). 44 int pic_order_cnt_type; 45 int top_field_order_cnt; 46 int bottom_field_order_cnt; 47 int pic_order_cnt; 48 int pic_order_cnt_msb; 49 int pic_order_cnt_lsb; 50 int delta_pic_order_cnt_bottom; 51 int delta_pic_order_cnt0; 52 int delta_pic_order_cnt1; 53 54 int pic_num; 55 int long_term_pic_num; 56 int frame_num; // from slice header 57 int frame_num_offset; 58 int frame_num_wrap; 59 int long_term_frame_idx; 60 61 H264SliceHeader::Type type; 62 int nal_ref_idc; 63 bool idr; // IDR picture? 64 int idr_pic_id; // Valid only if idr == true. 65 bool ref; // reference picture? 66 bool long_term; // long term reference picture? 67 bool outputted; 68 // Does memory management op 5 needs to be executed after this 69 // picture has finished decoding? 70 bool mem_mgmt_5; 71 72 // Created by the decoding process for gaps in frame_num. 73 // Not for decode or output. 74 bool nonexisting; 75 76 Field field; 77 78 // Values from slice_hdr to be used during reference marking and 79 // memory management after finishing this picture. 80 bool long_term_reference_flag; 81 bool adaptive_ref_pic_marking_mode_flag; 82 H264DecRefPicMarking ref_pic_marking[H264SliceHeader::kRefListSize]; 83 84 // Position in DPB (i.e. index in DPB). 85 int dpb_position; 86 87 // The visible size of picture. This could be either parsed from SPS, or set 88 // to Rect(0, 0) for indicating invalid values or not available. 89 Rect visible_rect; 90 91 protected: 92 friend class base::RefCountedThreadSafe<H264Picture>; 93 virtual ~H264Picture(); 94 95 private: 96 DISALLOW_COPY_AND_ASSIGN(H264Picture); 97 }; 98 99 // DPB - Decoded Picture Buffer. 100 // Stores decoded pictures that will be used for future display 101 // and/or reference. 102 class H264DPB { 103 public: 104 H264DPB(); 105 ~H264DPB(); 106 107 void set_max_num_pics(size_t max_num_pics); 108 size_t max_num_pics() const { return max_num_pics_; } 109 110 // Remove unused (not reference and already outputted) pictures from DPB 111 // and free it. 112 void DeleteUnused(); 113 114 // Remove a picture by its pic_order_cnt and free it. 115 void DeleteByPOC(int poc); 116 117 // Clear DPB. 118 void Clear(); 119 120 // Store picture in DPB. DPB takes ownership of its resources. 121 void StorePic(const scoped_refptr<H264Picture>& pic); 122 123 // Return the number of reference pictures in DPB. 124 int CountRefPics(); 125 126 // Mark all pictures in DPB as unused for reference. 127 void MarkAllUnusedForRef(); 128 129 // Return a short-term reference picture by its pic_num. 130 scoped_refptr<H264Picture> GetShortRefPicByPicNum(int pic_num); 131 132 // Return a long-term reference picture by its long_term_pic_num. 133 scoped_refptr<H264Picture> GetLongRefPicByLongTermPicNum(int pic_num); 134 135 // Return the short reference picture with lowest frame_num. Used for sliding 136 // window memory management. 137 scoped_refptr<H264Picture> GetLowestFrameNumWrapShortRefPic(); 138 139 // Append all pictures that have not been outputted yet to the passed |out| 140 // vector, sorted by lowest pic_order_cnt (in output order). 141 void GetNotOutputtedPicsAppending(H264Picture::Vector* out); 142 143 // Append all short term reference pictures to the passed |out| vector. 144 void GetShortTermRefPicsAppending(H264Picture::Vector* out); 145 146 // Append all long term reference pictures to the passed |out| vector. 147 void GetLongTermRefPicsAppending(H264Picture::Vector* out); 148 149 // Iterators for direct access to DPB contents. 150 // Will be invalidated after any of Remove* calls. 151 H264Picture::Vector::iterator begin() { return pics_.begin(); } 152 H264Picture::Vector::iterator end() { return pics_.end(); } 153 H264Picture::Vector::const_iterator begin() const { return pics_.begin(); } 154 H264Picture::Vector::const_iterator end() const { return pics_.end(); } 155 H264Picture::Vector::const_reverse_iterator rbegin() const { 156 return pics_.rbegin(); 157 } 158 H264Picture::Vector::const_reverse_iterator rend() const { 159 return pics_.rend(); 160 } 161 162 size_t size() const { return pics_.size(); } 163 bool IsFull() const { return pics_.size() == max_num_pics_; } 164 165 // Per H264 spec, increase to 32 if interlaced video is supported. 166 enum { 167 kDPBMaxSize = 16, 168 }; 169 170 private: 171 void UpdatePicPositions(); 172 173 H264Picture::Vector pics_; 174 size_t max_num_pics_; 175 176 DISALLOW_COPY_AND_ASSIGN(H264DPB); 177 }; 178 179 } // namespace media 180 181 #endif // H264_DPB_H_ 182
