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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// This file contains an implementation of an H.264 Decoded Picture Buffer
// used in H264 decoders.
#ifndef MEDIA_GPU_H264_DPB_H_
#define MEDIA_GPU_H264_DPB_H_
#include <stddef.h>
#include <vector>
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "media/gpu/codec_picture.h"
#include "media/gpu/media_gpu_export.h"
#include "media/video/h264_parser.h"
#include "ui/gfx/geometry/rect.h"
namespace media {
class V4L2H264Picture;
class VaapiH264Picture;
// A picture (a frame or a field) in the H.264 spec sense.
// See spec at
class MEDIA_GPU_EXPORT H264Picture : public CodecPicture {
using Vector = std::vector<scoped_refptr<H264Picture>>;
enum Field {
virtual V4L2H264Picture* AsV4L2H264Picture();
virtual VaapiH264Picture* AsVaapiH264Picture();
// Values calculated per H.264 specification or taken from slice header.
// See spec for more details on each (some names have been converted from
// CamelCase in spec to Chromium-style names).
int pic_order_cnt_type;
int top_field_order_cnt;
int bottom_field_order_cnt;
int pic_order_cnt;
int pic_order_cnt_msb;
int pic_order_cnt_lsb;
int delta_pic_order_cnt_bottom;
int delta_pic_order_cnt0;
int delta_pic_order_cnt1;
int pic_num;
int long_term_pic_num;
int frame_num; // from slice header
int frame_num_offset;
int frame_num_wrap;
int long_term_frame_idx;
H264SliceHeader::Type type;
int nal_ref_idc;
bool idr; // IDR picture?
int idr_pic_id; // Valid only if idr == true.
bool ref; // reference picture?
bool long_term; // long term reference picture?
bool outputted;
// Does memory management op 5 needs to be executed after this
// picture has finished decoding?
bool mem_mgmt_5;
// Created by the decoding process for gaps in frame_num.
// Not for decode or output.
bool nonexisting;
Field field;
// Values from slice_hdr to be used during reference marking and
// memory management after finishing this picture.
bool long_term_reference_flag;
bool adaptive_ref_pic_marking_mode_flag;
H264DecRefPicMarking ref_pic_marking[H264SliceHeader::kRefListSize];
// Position in DPB (i.e. index in DPB).
int dpb_position;
~H264Picture() override;
// DPB - Decoded Picture Buffer.
// Stores decoded pictures that will be used for future display
// and/or reference.
class H264DPB {
void set_max_num_pics(size_t max_num_pics);
size_t max_num_pics() const { return max_num_pics_; }
// Remove unused (not reference and already outputted) pictures from DPB
// and free it.
void DeleteUnused();
// Remove a picture by its pic_order_cnt and free it.
void DeleteByPOC(int poc);
// Clear DPB.
void Clear();
// Store picture in DPB. DPB takes ownership of its resources.
void StorePic(const scoped_refptr<H264Picture>& pic);
// Return the number of reference pictures in DPB.
int CountRefPics();
// Mark all pictures in DPB as unused for reference.
void MarkAllUnusedForRef();
// Return a short-term reference picture by its pic_num.
scoped_refptr<H264Picture> GetShortRefPicByPicNum(int pic_num);
// Return a long-term reference picture by its long_term_pic_num.
scoped_refptr<H264Picture> GetLongRefPicByLongTermPicNum(int pic_num);
// Return the short reference picture with lowest frame_num. Used for sliding
// window memory management.
scoped_refptr<H264Picture> GetLowestFrameNumWrapShortRefPic();
// Append all pictures that have not been outputted yet to the passed |out|
// vector, sorted by lowest pic_order_cnt (in output order).
void GetNotOutputtedPicsAppending(H264Picture::Vector* out);
// Append all short term reference pictures to the passed |out| vector.
void GetShortTermRefPicsAppending(H264Picture::Vector* out);
// Append all long term reference pictures to the passed |out| vector.
void GetLongTermRefPicsAppending(H264Picture::Vector* out);
// Iterators for direct access to DPB contents.
// Will be invalidated after any of Remove* calls.
H264Picture::Vector::iterator begin() { return pics_.begin(); }
H264Picture::Vector::iterator end() { return pics_.end(); }
H264Picture::Vector::const_iterator begin() const { return pics_.begin(); }
H264Picture::Vector::const_iterator end() const { return pics_.end(); }
H264Picture::Vector::const_reverse_iterator rbegin() const {
return pics_.rbegin();
H264Picture::Vector::const_reverse_iterator rend() const {
return pics_.rend();
size_t size() const { return pics_.size(); }
bool IsFull() const { return pics_.size() == max_num_pics_; }
// Per H264 spec, increase to 32 if interlaced video is supported.
enum {
kDPBMaxSize = 16,
void UpdatePicPositions();
H264Picture::Vector pics_;
size_t max_num_pics_;
} // namespace media
#endif // MEDIA_GPU_H264_DPB_H_