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/ref_counted.h"
  15 #include "media/filters/h264_parser.h"
  16
  17 namespace content {
  18
  19 class V4L2H264Picture;
  20 class VaapiH264Picture;
  21
  22 // A picture (a frame or a field) in the H.264 spec sense.
  23 // See spec at http://www.itu.int/rec/T-REC-H.264
  24 class H264Picture : public base::RefCounted<H264Picture> {
  25  public:
  26   using Vector = std::vector<scoped_refptr<H264Picture>>;
  27
  28   enum Field {
  29     FIELD_NONE,
  30     FIELD_TOP,
  31     FIELD_BOTTOM,
  32   };
  33
  34   H264Picture();
  35
  36   virtual V4L2H264Picture* AsV4L2H264Picture();
  37   virtual VaapiH264Picture* AsVaapiH264Picture();
  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 top_field_order_cnt;
  43   int bottom_field_order_cnt;
  44   int pic_order_cnt;
  45   int pic_order_cnt_msb;
  46   int pic_order_cnt_lsb;
  47
  48   int pic_num;
  49   int long_term_pic_num;
  50   int frame_num;  // from slice header
  51   int frame_num_offset;
  52   int frame_num_wrap;
  53   int long_term_frame_idx;
  54
  55   media::H264SliceHeader::Type type;
  56   bool idr;  // IDR picture?
  57   bool ref;  // reference picture?
  58   bool long_term;  // long term reference picture?
  59   bool outputted;
  60   // Does memory management op 5 needs to be executed after this
  61   // picture has finished decoding?
  62   bool mem_mgmt_5;
  63
  64   Field field;
  65
  66   // Values from slice_hdr to be used during reference marking and
  67   // memory management after finishing this picture.
  68   bool long_term_reference_flag;
  69   bool adaptive_ref_pic_marking_mode_flag;
  70   media::H264DecRefPicMarking
  71       ref_pic_marking[media::H264SliceHeader::kRefListSize];
  72
  73   // Position in DPB (i.e. index in DPB).
  74   int dpb_position;
  75
  76  protected:
  77   friend class base::RefCounted<H264Picture>;
  78   virtual ~H264Picture();
  79
  80  private:
  81   DISALLOW_COPY_AND_ASSIGN(H264Picture);
  82 };
  83
  84 // DPB - Decoded Picture Buffer.
  85 // Stores decoded pictures that will be used for future display
  86 // and/or reference.
  87 class H264DPB {
  88  public:
  89   H264DPB();
  90   ~H264DPB();
  91
  92   void set_max_num_pics(size_t max_num_pics);
  93   size_t max_num_pics() const { return max_num_pics_; }
  94
  95   // Remove unused (not reference and already outputted) pictures from DPB
  96   // and free it.
  97   void DeleteUnused();
  98
  99   // Remove a picture by its pic_order_cnt and free it.
 100   void DeleteByPOC(int poc);
 101
 102   // Clear DPB.
 103   void Clear();
 104
 105   // Store picture in DPB. DPB takes ownership of its resources.
 106   void StorePic(const scoped_refptr<H264Picture>& pic);
 107
 108   // Return the number of reference pictures in DPB.
 109   int CountRefPics();
 110
 111   // Mark all pictures in DPB as unused for reference.
 112   void MarkAllUnusedForRef();
 113
 114   // Return a short-term reference picture by its pic_num.
 115   scoped_refptr<H264Picture> GetShortRefPicByPicNum(int pic_num);
 116
 117   // Return a long-term reference picture by its long_term_pic_num.
 118   scoped_refptr<H264Picture> GetLongRefPicByLongTermPicNum(int pic_num);
 119
 120   // Return the short reference picture with lowest frame_num. Used for sliding
 121   // window memory management.
 122   scoped_refptr<H264Picture> GetLowestFrameNumWrapShortRefPic();
 123
 124   // Append all pictures that have not been outputted yet to the passed |out|
 125   // vector, sorted by lowest pic_order_cnt (in output order).
 126   void GetNotOutputtedPicsAppending(H264Picture::Vector* out);
 127
 128   // Append all short term reference pictures to the passed |out| vector.
 129   void GetShortTermRefPicsAppending(H264Picture::Vector* out);
 130
 131   // Append all long term reference pictures to the passed |out| vector.
 132   void GetLongTermRefPicsAppending(H264Picture::Vector* out);
 133
 134   // Iterators for direct access to DPB contents.
 135   // Will be invalidated after any of Remove* calls.
 136   H264Picture::Vector::iterator begin() { return pics_.begin(); }
 137   H264Picture::Vector::iterator end() { return pics_.end(); }
 138   H264Picture::Vector::const_iterator begin() const { return pics_.begin(); }
 139   H264Picture::Vector::const_iterator end() const { return pics_.end(); }
 140   H264Picture::Vector::const_reverse_iterator rbegin() const {
 141     return pics_.rbegin();
 142   }
 143   H264Picture::Vector::const_reverse_iterator rend() const {
 144     return pics_.rend();
 145   }
 146
 147   size_t size() const { return pics_.size(); }
 148   bool IsFull() const { return pics_.size() == max_num_pics_; }
 149
 150   // Per H264 spec, increase to 32 if interlaced video is supported.
 151   enum { kDPBMaxSize = 16, };
 152
 153  private:
 154   void UpdatePicPositions();
 155
 156   H264Picture::Vector pics_;
 157   size_t max_num_pics_;
 158
 159   DISALLOW_COPY_AND_ASSIGN(H264DPB);
 160 };
 161
 162 }  // namespace content
 163
 164 #endif  // CONTENT_COMMON_GPU_MEDIA_H264_DPB_H_