1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
|
// Copyright 2019 The libgav1 Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include <algorithm>
#include <cstdint>
#include <cstring>
#include "src/dsp/constants.h"
#include "src/obu_parser.h"
#include "src/symbol_decoder_context.h"
#include "src/tile.h"
#include "src/utils/array_2d.h"
#include "src/utils/block_parameters_holder.h"
#include "src/utils/common.h"
#include "src/utils/constants.h"
#include "src/utils/entropy_decoder.h"
#include "src/utils/segmentation.h"
#include "src/utils/stack.h"
#include "src/utils/types.h"
namespace libgav1 {
namespace {
constexpr uint8_t kMaxVariableTransformTreeDepth = 2;
// Max_Tx_Depth array from section 5.11.5 in the spec with the following
// modification: If the element is not zero, it is subtracted by one. That is
// the only way in which this array is being used.
constexpr int kTxDepthCdfIndex[kMaxBlockSizes] = {
0, 0, 1, 0, 0, 1, 2, 1, 1, 1, 2, 3, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3};
constexpr TransformSize kMaxTransformSizeRectangle[kMaxBlockSizes] = {
kTransformSize4x4, kTransformSize4x8, kTransformSize4x16,
kTransformSize8x4, kTransformSize8x8, kTransformSize8x16,
kTransformSize8x32, kTransformSize16x4, kTransformSize16x8,
kTransformSize16x16, kTransformSize16x32, kTransformSize16x64,
kTransformSize32x8, kTransformSize32x16, kTransformSize32x32,
kTransformSize32x64, kTransformSize64x16, kTransformSize64x32,
kTransformSize64x64, kTransformSize64x64, kTransformSize64x64,
kTransformSize64x64};
TransformSize GetSquareTransformSize(uint8_t pixels) {
switch (pixels) {
case 128:
case 64:
return kTransformSize64x64;
case 32:
return kTransformSize32x32;
case 16:
return kTransformSize16x16;
case 8:
return kTransformSize8x8;
default:
return kTransformSize4x4;
}
}
} // namespace
int Tile::GetTopTransformWidth(const Block& block, int row4x4, int column4x4,
bool ignore_skip) {
if (row4x4 == block.row4x4) {
if (!block.top_available[kPlaneY]) return 64;
const BlockParameters& bp_top =
*block_parameters_holder_.Find(row4x4 - 1, column4x4);
if ((ignore_skip || bp_top.skip) && bp_top.is_inter) {
return kBlockWidthPixels[bp_top.size];
}
}
return kTransformWidth[inter_transform_sizes_[row4x4 - 1][column4x4]];
}
int Tile::GetLeftTransformHeight(const Block& block, int row4x4, int column4x4,
bool ignore_skip) {
if (column4x4 == block.column4x4) {
if (!block.left_available[kPlaneY]) return 64;
const BlockParameters& bp_left =
*block_parameters_holder_.Find(row4x4, column4x4 - 1);
if ((ignore_skip || bp_left.skip) && bp_left.is_inter) {
return kBlockHeightPixels[bp_left.size];
}
}
return kTransformHeight[inter_transform_sizes_[row4x4][column4x4 - 1]];
}
TransformSize Tile::ReadFixedTransformSize(const Block& block) {
BlockParameters& bp = *block.bp;
if (frame_header_.segmentation.lossless[bp.segment_id]) {
return kTransformSize4x4;
}
const TransformSize max_rect_tx_size = kMaxTransformSizeRectangle[block.size];
const bool allow_select = !bp.skip || !bp.is_inter;
if (block.size == kBlock4x4 || !allow_select ||
frame_header_.tx_mode != kTxModeSelect) {
return max_rect_tx_size;
}
const int max_tx_width = kTransformWidth[max_rect_tx_size];
const int max_tx_height = kTransformHeight[max_rect_tx_size];
const int top_width =
block.top_available[kPlaneY]
? GetTopTransformWidth(block, block.row4x4, block.column4x4, true)
: 0;
const int left_height =
block.left_available[kPlaneY]
? GetLeftTransformHeight(block, block.row4x4, block.column4x4, true)
: 0;
const auto context = static_cast<int>(top_width >= max_tx_width) +
static_cast<int>(left_height >= max_tx_height);
const int cdf_index = kTxDepthCdfIndex[block.size];
uint16_t* const cdf =
symbol_decoder_context_.tx_depth_cdf[cdf_index][context];
const int tx_depth = (cdf_index == 0)
? static_cast<int>(reader_.ReadSymbol(cdf))
: reader_.ReadSymbol<3>(cdf);
assert(tx_depth < 3);
TransformSize tx_size = max_rect_tx_size;
if (tx_depth == 0) return tx_size;
tx_size = kSplitTransformSize[tx_size];
if (tx_depth == 1) return tx_size;
return kSplitTransformSize[tx_size];
}
void Tile::ReadVariableTransformTree(const Block& block, int row4x4,
int column4x4, TransformSize tx_size) {
const uint8_t pixels = std::max(block.width, block.height);
const TransformSize max_tx_size = GetSquareTransformSize(pixels);
const int context_delta = (kNumSquareTransformSizes - 1 -
TransformSizeToSquareTransformIndex(max_tx_size)) *
6;
// Branching factor is 4 and maximum depth is 2. So the maximum stack size
// necessary is (4 - 1) + 4 = 7.
Stack<TransformTreeNode, 7> stack;
stack.Push(TransformTreeNode(column4x4, row4x4, tx_size, 0));
do {
TransformTreeNode node = stack.Pop();
const int tx_width4x4 = kTransformWidth4x4[node.tx_size];
const int tx_height4x4 = kTransformHeight4x4[node.tx_size];
if (node.tx_size != kTransformSize4x4 &&
node.depth != kMaxVariableTransformTreeDepth) {
const auto top =
static_cast<int>(GetTopTransformWidth(block, node.y, node.x, false) <
kTransformWidth[node.tx_size]);
const auto left = static_cast<int>(
GetLeftTransformHeight(block, node.y, node.x, false) <
kTransformHeight[node.tx_size]);
const int context =
static_cast<int>(max_tx_size > kTransformSize8x8 &&
kTransformSizeSquareMax[node.tx_size] !=
max_tx_size) *
3 +
context_delta + top + left;
// tx_split.
if (reader_.ReadSymbol(symbol_decoder_context_.tx_split_cdf[context])) {
const TransformSize sub_tx_size = kSplitTransformSize[node.tx_size];
const int step_width4x4 = kTransformWidth4x4[sub_tx_size];
const int step_height4x4 = kTransformHeight4x4[sub_tx_size];
// The loops have to run in reverse order because we use a stack for
// DFS.
for (int i = tx_height4x4 - step_height4x4; i >= 0;
i -= step_height4x4) {
for (int j = tx_width4x4 - step_width4x4; j >= 0;
j -= step_width4x4) {
if (node.y + i >= frame_header_.rows4x4 ||
node.x + j >= frame_header_.columns4x4) {
continue;
}
stack.Push(TransformTreeNode(node.x + j, node.y + i, sub_tx_size,
node.depth + 1));
}
}
continue;
}
}
// tx_split is false.
for (int i = 0; i < tx_height4x4; ++i) {
static_assert(sizeof(TransformSize) == 1, "");
memset(&inter_transform_sizes_[node.y + i][node.x], node.tx_size,
tx_width4x4);
}
block_parameters_holder_.Find(node.y, node.x)->transform_size =
node.tx_size;
} while (!stack.Empty());
}
void Tile::DecodeTransformSize(const Block& block) {
BlockParameters& bp = *block.bp;
if (frame_header_.tx_mode == kTxModeSelect && block.size > kBlock4x4 &&
bp.is_inter && !bp.skip &&
!frame_header_.segmentation.lossless[bp.segment_id]) {
const TransformSize max_tx_size = kMaxTransformSizeRectangle[block.size];
const int tx_width4x4 = kTransformWidth4x4[max_tx_size];
const int tx_height4x4 = kTransformHeight4x4[max_tx_size];
for (int row = block.row4x4; row < block.row4x4 + block.height4x4;
row += tx_height4x4) {
for (int column = block.column4x4;
column < block.column4x4 + block.width4x4; column += tx_width4x4) {
ReadVariableTransformTree(block, row, column, max_tx_size);
}
}
} else {
bp.transform_size = ReadFixedTransformSize(block);
for (int row = block.row4x4; row < block.row4x4 + block.height4x4; ++row) {
static_assert(sizeof(TransformSize) == 1, "");
memset(&inter_transform_sizes_[row][block.column4x4], bp.transform_size,
block.width4x4);
}
}
}
} // namespace libgav1
|
