content/common/gpu/media/h264_dpb.h

   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 "content/common/gpu/media/h264_parser.h"
  16
  17 namespace 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
  21 struct 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   bool idr;  // IDR picture?
  45   bool ref;  // reference picture?
  46   bool long_term;  // long term reference picture?
  47   bool outputted;
  48   // Does memory management op 5 needs to be executed after this
  49   // picture has finished decoding?
  50   bool mem_mgmt_5;
  51
  52   Field field;
  53
  54   // Values from slice_hdr to be used during reference marking and
  55   // memory management after finishing this picture.
  56   bool long_term_reference_flag;
  57   bool adaptive_ref_pic_marking_mode_flag;
  58   H264DecRefPicMarking ref_pic_marking[H264SliceHeader::kRefListSize];
  59
  60   typedef std::vector<H264Picture*> PtrVector;
  61 };
  62
  63 // DPB - Decoded Picture Buffer.
  64 // Stores decoded pictures that will be used for future display
  65 // and/or reference.
  66 class H264DPB {
  67  public:
  68   H264DPB();
  69   ~H264DPB();
  70
  71   void set_max_num_pics(size_t max_num_pics);
  72   size_t max_num_pics() { return max_num_pics_; }
  73
  74   // Remove unused (not reference and already outputted) pictures from DPB
  75   // and free it.
  76   void DeleteUnused();
  77
  78   // Remove a picture by its pic_order_cnt and free it.
  79   void DeleteByPOC(int poc);
  80
  81   // Clear DPB.
  82   void Clear();
  83
  84   // Store picture in DPB. DPB takes ownership of its resources.
  85   void StorePic(H264Picture* pic);
  86
  87   // Return the number of reference pictures in DPB.
  88   int CountRefPics();
  89
  90   // Mark all pictures in DPB as unused for reference.
  91   void MarkAllUnusedForRef();
  92
  93   // Return a short-term reference picture by its pic_num.
  94   H264Picture* GetShortRefPicByPicNum(int pic_num);
  95
  96   // Return a long-term reference picture by its long_term_pic_num.
  97   H264Picture* GetLongRefPicByLongTermPicNum(int pic_num);
  98
  99   // Return the short reference picture with lowest frame_num. Used for sliding
 100   // window memory management.
 101   H264Picture* GetLowestFrameNumWrapShortRefPic();
 102
 103   // Append all pictures that have not been outputted yet to the passed |out|
 104   // vector, sorted by lowest pic_order_cnt (in output order).
 105   void GetNotOutputtedPicsAppending(H264Picture::PtrVector& out);
 106
 107   // Append all short term reference pictures to the passed |out| vector.
 108   void GetShortTermRefPicsAppending(H264Picture::PtrVector& out);
 109
 110   // Append all long term reference pictures to the passed |out| vector.
 111   void GetLongTermRefPicsAppending(H264Picture::PtrVector& out);
 112
 113   // Iterators for direct access to DPB contents.
 114   // Will be invalidated after any of Remove* calls.
 115   typedef ScopedVector<H264Picture> Pictures;
 116   Pictures::iterator begin() { return pics_.begin(); }
 117   Pictures::iterator end() { return pics_.end(); }
 118   Pictures::reverse_iterator rbegin() { return pics_.rbegin(); }
 119   Pictures::reverse_iterator rend() { return pics_.rend(); }
 120
 121   size_t size() const { return pics_.size(); }
 122   bool IsFull() const { return pics_.size() == max_num_pics_; }
 123
 124   // Per H264 spec, increase to 32 if interlaced video is supported.
 125   enum { kDPBMaxSize = 16, };
 126
 127  private:
 128   Pictures pics_;
 129   size_t max_num_pics_;
 130
 131   DISALLOW_COPY_AND_ASSIGN(H264DPB);
 132 };
 133
 134 }  // namespace content
 135
 136 #endif  // CONTENT_COMMON_GPU_MEDIA_H264_DPB_H_