1 /*
2 * Copyright (c) 2016, Alliance for Open Media. All rights reserved
3 *
4 * This source code is subject to the terms of the BSD 2 Clause License and
5 * the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
6 * was not distributed with this source code in the LICENSE file, you can
7 * obtain it at www.aomedia.org/license/software. If the Alliance for Open
8 * Media Patent License 1.0 was not distributed with this source code in the
9 * PATENTS file, you can obtain it at www.aomedia.org/license/patent.
10 */
11
12 #include <limits.h>
13 #include <math.h>
14
15 #include "av1/encoder/aq_complexity.h"
16 #include "av1/encoder/aq_variance.h"
17 #include "av1/encoder/encodeframe.h"
18 #include "av1/common/seg_common.h"
19 #include "av1/encoder/segmentation.h"
20 #include "aom_dsp/aom_dsp_common.h"
21 #include "aom_ports/system_state.h"
22
23 #define AQ_C_SEGMENTS 5
24 #define DEFAULT_AQ2_SEG 3 // Neutral Q segment
25 #define AQ_C_STRENGTHS 3
26 static const double aq_c_q_adj_factor[AQ_C_STRENGTHS][AQ_C_SEGMENTS] = {
27 { 1.75, 1.25, 1.05, 1.00, 0.90 },
28 { 2.00, 1.50, 1.15, 1.00, 0.85 },
29 { 2.50, 1.75, 1.25, 1.00, 0.80 }
30 };
31 static const double aq_c_transitions[AQ_C_STRENGTHS][AQ_C_SEGMENTS] = {
32 { 0.15, 0.30, 0.55, 2.00, 100.0 },
33 { 0.20, 0.40, 0.65, 2.00, 100.0 },
34 { 0.25, 0.50, 0.75, 2.00, 100.0 }
35 };
36 static const double aq_c_var_thresholds[AQ_C_STRENGTHS][AQ_C_SEGMENTS] = {
37 { -4.0, -3.0, -2.0, 100.00, 100.0 },
38 { -3.5, -2.5, -1.5, 100.00, 100.0 },
39 { -3.0, -2.0, -1.0, 100.00, 100.0 }
40 };
41
get_aq_c_strength(int q_index,aom_bit_depth_t bit_depth)42 static int get_aq_c_strength(int q_index, aom_bit_depth_t bit_depth) {
43 // Approximate base quatizer (truncated to int)
44 const int base_quant = av1_ac_quant_Q3(q_index, 0, bit_depth) / 4;
45 return (base_quant > 10) + (base_quant > 25);
46 }
47
av1_setup_in_frame_q_adj(AV1_COMP * cpi)48 void av1_setup_in_frame_q_adj(AV1_COMP *cpi) {
49 AV1_COMMON *const cm = &cpi->common;
50 struct segmentation *const seg = &cm->seg;
51 int resolution_change =
52 cm->prev_frame && (cm->width != cm->prev_frame->width ||
53 cm->height != cm->prev_frame->height);
54
55 // Make SURE use of floating point in this function is safe.
56 aom_clear_system_state();
57
58 if (resolution_change) {
59 memset(cpi->segmentation_map, 0, cm->mi_rows * cm->mi_cols);
60 av1_clearall_segfeatures(seg);
61 av1_disable_segmentation(seg);
62 return;
63 }
64
65 if (frame_is_intra_only(cm) || cm->error_resilient_mode ||
66 cpi->refresh_alt_ref_frame ||
67 (cpi->refresh_golden_frame && !cpi->rc.is_src_frame_alt_ref)) {
68 int segment;
69 const int aq_strength =
70 get_aq_c_strength(cm->base_qindex, cm->seq_params.bit_depth);
71
72 // Clear down the segment map.
73 memset(cpi->segmentation_map, DEFAULT_AQ2_SEG, cm->mi_rows * cm->mi_cols);
74
75 av1_clearall_segfeatures(seg);
76
77 // Segmentation only makes sense if the target bits per SB is above a
78 // threshold. Below this the overheads will usually outweigh any benefit.
79 if (cpi->rc.sb64_target_rate < 256) {
80 av1_disable_segmentation(seg);
81 return;
82 }
83
84 av1_enable_segmentation(seg);
85
86 // Default segment "Q" feature is disabled so it defaults to the baseline Q.
87 av1_disable_segfeature(seg, DEFAULT_AQ2_SEG, SEG_LVL_ALT_Q);
88
89 // Use some of the segments for in frame Q adjustment.
90 for (segment = 0; segment < AQ_C_SEGMENTS; ++segment) {
91 int qindex_delta;
92
93 if (segment == DEFAULT_AQ2_SEG) continue;
94
95 qindex_delta = av1_compute_qdelta_by_rate(
96 &cpi->rc, cm->current_frame.frame_type, cm->base_qindex,
97 aq_c_q_adj_factor[aq_strength][segment], cm->seq_params.bit_depth);
98
99 // For AQ complexity mode, we dont allow Q0 in a segment if the base
100 // Q is not 0. Q0 (lossless) implies 4x4 only and in AQ mode 2 a segment
101 // Q delta is sometimes applied without going back around the rd loop.
102 // This could lead to an illegal combination of partition size and q.
103 if ((cm->base_qindex != 0) && ((cm->base_qindex + qindex_delta) == 0)) {
104 qindex_delta = -cm->base_qindex + 1;
105 }
106 if ((cm->base_qindex + qindex_delta) > 0) {
107 av1_enable_segfeature(seg, segment, SEG_LVL_ALT_Q);
108 av1_set_segdata(seg, segment, SEG_LVL_ALT_Q, qindex_delta);
109 }
110 }
111 }
112 }
113
114 #define DEFAULT_LV_THRESH 10.0
115 #define MIN_DEFAULT_LV_THRESH 8.0
116 // Select a segment for the current block.
117 // The choice of segment for a block depends on the ratio of the projected
118 // bits for the block vs a target average and its spatial complexity.
av1_caq_select_segment(const AV1_COMP * cpi,MACROBLOCK * mb,BLOCK_SIZE bs,int mi_row,int mi_col,int projected_rate)119 void av1_caq_select_segment(const AV1_COMP *cpi, MACROBLOCK *mb, BLOCK_SIZE bs,
120 int mi_row, int mi_col, int projected_rate) {
121 const AV1_COMMON *const cm = &cpi->common;
122 const int num_planes = av1_num_planes(cm);
123
124 const int mi_offset = mi_row * cm->mi_cols + mi_col;
125 const int xmis = AOMMIN(cm->mi_cols - mi_col, mi_size_wide[bs]);
126 const int ymis = AOMMIN(cm->mi_rows - mi_row, mi_size_high[bs]);
127 int x, y;
128 int i;
129 unsigned char segment;
130
131 if (0) {
132 segment = DEFAULT_AQ2_SEG;
133 } else {
134 // Rate depends on fraction of a SB64 in frame (xmis * ymis / bw * bh).
135 // It is converted to bits << AV1_PROB_COST_SHIFT units.
136 const int64_t num = (int64_t)(cpi->rc.sb64_target_rate * xmis * ymis)
137 << AV1_PROB_COST_SHIFT;
138 const int denom = cm->seq_params.mib_size * cm->seq_params.mib_size;
139 const int target_rate = (int)(num / denom);
140 double logvar;
141 double low_var_thresh;
142 const int aq_strength =
143 get_aq_c_strength(cm->base_qindex, cm->seq_params.bit_depth);
144
145 aom_clear_system_state();
146 low_var_thresh =
147 (cpi->oxcf.pass == 2)
148 ? AOMMAX(exp(cpi->twopass.mb_av_energy), MIN_DEFAULT_LV_THRESH)
149 : DEFAULT_LV_THRESH;
150
151 av1_setup_src_planes(mb, cpi->source, mi_row, mi_col, num_planes, bs);
152 logvar = av1_log_block_var(cpi, mb, bs);
153
154 segment = AQ_C_SEGMENTS - 1; // Just in case no break out below.
155 for (i = 0; i < AQ_C_SEGMENTS; ++i) {
156 // Test rate against a threshold value and variance against a threshold.
157 // Increasing segment number (higher variance and complexity) = higher Q.
158 if ((projected_rate < target_rate * aq_c_transitions[aq_strength][i]) &&
159 (logvar < (low_var_thresh + aq_c_var_thresholds[aq_strength][i]))) {
160 segment = i;
161 break;
162 }
163 }
164 }
165
166 // Fill in the entires in the segment map corresponding to this SB64.
167 for (y = 0; y < ymis; y++) {
168 for (x = 0; x < xmis; x++) {
169 cpi->segmentation_map[mi_offset + y * cm->mi_cols + x] = segment;
170 }
171 }
172 }
173