// Copyright 2023 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "media/parsers/h266_poc.h"
#include <stddef.h>
#include <algorithm>
#include "base/logging.h"
#include "media/parsers/h266_parser.h"
namespace media {
H266POC::H266POC() {
Reset();
}
H266POC::~H266POC() = default;
H266RefEntry::H266RefEntry(int type, int poc, int layer)
: entry_type(type), pic_order_cnt(poc), nuh_layer_id(layer) {}
void H266POC::Reset() {
ref_pic_order_cnt_msb_ = 0;
ref_pic_order_cnt_lsb_ = 0;
}
// 8.3.1 Decoding process for picture order count. At present multi-layer
// encoded stream is excluded from decoder support, so each AU is expected
// to only contain one PU, and decoder will pass the first slice for the
// POC calculation.
int32_t H266POC::ComputePicOrderCnt(const H266SPS* sps,
const H266PPS* pps,
const H266VPS* vps,
const H266PictureHeader* ph,
const H266SliceHeader& slice_hdr) {
DCHECK(sps && pps && vps && ph);
int32_t pic_order_cnt = 0;
int32_t max_pic_order_cnt_lsb =
1 << (sps->sps_log2_max_pic_order_cnt_lsb_minus4 + 4);
int32_t pic_order_cnt_msb;
bool clvss_pic_flag = false, irap_pic = false, gdr_pic = false;
int curr_layer_idx = vps->GetGeneralLayerIdx(slice_hdr.nuh_layer_id);
if (curr_layer_idx < 0) {
DVLOG(1) << "Current slice's layer index is invalid.";
return -1;
}
// If vps marks layer dependencies, and certain PU in current AU
// with nuh_layer_id that GeneralLayerIdx[nuh_layer_id] is in the list
// ReferenceLayerIdx[curr_layer_idx], PicOrderCntVal should be equal to that
// PU's PicOrderCntVal, and ph_pic_order_cnt_lsb shall be the same for all
// slices in current AU.
// TODO(crbugs.com/1417910): Allow multi-layer streams.
if (vps->vps_max_layers_minus1 > 0) {
DVLOG(1) << "Multi-layer stream is not supported.";
return -1;
}
irap_pic = slice_hdr.nal_unit_type >= H266NALU::kIDRWithRADL &&
slice_hdr.nal_unit_type <= H266NALU::kCRA;
gdr_pic = slice_hdr.nal_unit_type == H266NALU::kGDR;
clvss_pic_flag =
(irap_pic || gdr_pic) && slice_hdr.no_output_before_recovery_flag;
int32_t prev_pic_order_cnt_lsb = ref_pic_order_cnt_lsb_,
prev_pic_oder_cnt_msb = ref_pic_order_cnt_msb_;
// Calculate POC for current picture.
if (ph->ph_poc_msb_cycle_present_flag) {
pic_order_cnt_msb = ph->ph_poc_msb_cycle_val * max_pic_order_cnt_lsb;
} else {
if (clvss_pic_flag) {
pic_order_cnt_msb = 0;
} else {
if (ph->ph_pic_order_cnt_lsb < prev_pic_order_cnt_lsb &&
prev_pic_order_cnt_lsb - ph->ph_pic_order_cnt_lsb >=
max_pic_order_cnt_lsb / 2) {
pic_order_cnt_msb = prev_pic_oder_cnt_msb + max_pic_order_cnt_lsb;
} else if (ph->ph_pic_order_cnt_lsb > prev_pic_order_cnt_lsb &&
(ph->ph_pic_order_cnt_lsb - prev_pic_order_cnt_lsb >
max_pic_order_cnt_lsb / 2)) {
pic_order_cnt_msb = prev_pic_oder_cnt_msb - max_pic_order_cnt_lsb;
} else {
pic_order_cnt_msb = prev_pic_oder_cnt_msb;
}
}
}
// 8.3.1: Decoding process for picture order count.
if (!slice_hdr.temporal_id && !ph->ph_non_ref_pic_flag &&
(slice_hdr.nal_unit_type != H266NALU::kRADL &&
slice_hdr.nal_unit_type != H266NALU::kRASL)) {
ref_pic_order_cnt_lsb_ = ph->ph_pic_order_cnt_lsb;
ref_pic_order_cnt_msb_ = pic_order_cnt_msb;
}
pic_order_cnt = pic_order_cnt_msb + ph->ph_pic_order_cnt_lsb;
return pic_order_cnt;
}
// 8.3.2: Decoding process for reference picture lists construction.
void H266POC::ComputeRefPicPocList(
const H266SPS* sps,
const H266PPS* pps,
const H266VPS* vps,
const H266PictureHeader* ph,
const H266SliceHeader& slice_hdr,
int current_poc,
std::vector<H266RefEntry>& ref_pic_poc_list0,
std::vector<H266RefEntry>& ref_pic_poc_list1) {
DCHECK(sps && pps && vps && ph);
DCHECK(current_poc >= 0);
ref_pic_poc_list0.clear();
ref_pic_poc_list1.clear();
const H266RefPicLists* ref_pic_lists = nullptr;
if ((slice_hdr.nal_unit_type == H266NALU::kIDRNoLeadingPicture ||
slice_hdr.nal_unit_type == H266NALU::kIDRWithRADL) &&
!sps->sps_idr_rpl_present_flag) {
return;
}
if (pps->pps_rpl_info_in_ph_flag) {
ref_pic_lists = &ph->ref_pic_lists;
} else {
ref_pic_lists = &slice_hdr.ref_pic_lists;
}
for (int i = 0; i < 2; i++) {
const H266RefPicListStruct* ref_pic_list_struct = nullptr;
if (ref_pic_lists->rpl_sps_flag[i]) {
ref_pic_list_struct =
&sps->ref_pic_list_struct[i][ref_pic_lists->rpl_idx[i]];
} else {
ref_pic_list_struct = &ref_pic_lists->rpl_ref_lists[i];
}
int poc_base = current_poc;
int ltrp_entry_handled = 0;
for (int j = 0; j < ref_pic_list_struct->num_ref_entries; j++) {
// STRP
if (!ref_pic_list_struct->inter_layer_ref_pic_flag[j] &&
ref_pic_list_struct->st_ref_pic_flag[j]) {
poc_base += ref_pic_list_struct->delta_poc_val_st[j];
if (i == 0) {
ref_pic_poc_list0.emplace_back(H266RefEntry::kSTRP, poc_base,
slice_hdr.nuh_layer_id);
} else {
ref_pic_poc_list1.emplace_back(H266RefEntry::kSTRP, poc_base,
slice_hdr.nuh_layer_id);
}
} else if (!ref_pic_list_struct->inter_layer_ref_pic_flag[j] &&
!ref_pic_list_struct->st_ref_pic_flag[j]) { // LTRP
int poc_lsb_lt = ref_pic_list_struct->ltrp_in_header_flag
? ref_pic_lists->poc_lsb_lt[i][ltrp_entry_handled]
: ref_pic_list_struct->rpls_poc_lsb_lt[j];
int full_poc_lt =
current_poc -
ref_pic_lists
->unpacked_delta_poc_msb_cycle_lt[i][ltrp_entry_handled] *
sps->max_pic_order_cnt_lsb -
(current_poc & (sps->max_pic_order_cnt_lsb - 1)) + poc_lsb_lt;
int poc_entry_val =
ref_pic_lists
->delta_poc_msb_cycle_present_flag[i][ltrp_entry_handled]
? full_poc_lt
: poc_lsb_lt;
if (i == 0) {
ref_pic_poc_list0.emplace_back(H266RefEntry::kLTRP, poc_entry_val,
slice_hdr.nuh_layer_id);
} else {
ref_pic_poc_list1.emplace_back(H266RefEntry::kLTRP, poc_entry_val,
slice_hdr.nuh_layer_id);
}
ltrp_entry_handled++;
} else { // ILRP
// For inter-layer reference, just keep a record in reference picture
// list. The location in DPB for the dependent layer picture needs to be
// checked during runtime by decoder.
if (i == 0) {
ref_pic_poc_list0.emplace_back(H266RefEntry::kILRP, current_poc,
ref_pic_list_struct->ilrp_idx[j]);
} else {
ref_pic_poc_list1.emplace_back(H266RefEntry::kILRP, current_poc,
ref_pic_list_struct->ilrp_idx[j]);
}
}
}
}
}
} // namespace media
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