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
22 #define AQ_C_SEGMENTS 5
23 #define DEFAULT_AQ2_SEG 3 // Neutral Q segment
24 #define AQ_C_STRENGTHS 3
25 static const double aq_c_q_adj_factor[AQ_C_STRENGTHS][AQ_C_SEGMENTS] = {
26 { 1.75, 1.25, 1.05, 1.00, 0.90 },
27 { 2.00, 1.50, 1.15, 1.00, 0.85 },
28 { 2.50, 1.75, 1.25, 1.00, 0.80 }
29 };
30 static const double aq_c_transitions[AQ_C_STRENGTHS][AQ_C_SEGMENTS] = {
31 { 0.15, 0.30, 0.55, 2.00, 100.0 },
32 { 0.20, 0.40, 0.65, 2.00, 100.0 },
33 { 0.25, 0.50, 0.75, 2.00, 100.0 }
34 };
35 static const double aq_c_var_thresholds[AQ_C_STRENGTHS][AQ_C_SEGMENTS] = {
36 { -4.0, -3.0, -2.0, 100.00, 100.0 },
37 { -3.5, -2.5, -1.5, 100.00, 100.0 },
38 { -3.0, -2.0, -1.0, 100.00, 100.0 }
39 };
40
get_aq_c_strength(int q_index,aom_bit_depth_t bit_depth)41 static int get_aq_c_strength(int q_index, aom_bit_depth_t bit_depth) {
42 // Approximate base quatizer (truncated to int)
43 const int base_quant = av1_ac_quant_QTX(q_index, 0, bit_depth) / 4;
44 return (base_quant > 10) + (base_quant > 25);
45 }
46
is_frame_aq_enabled(const AV1_COMP * const cpi)47 static bool is_frame_aq_enabled(const AV1_COMP *const cpi) {
48 const AV1_COMMON *const cm = &cpi->common;
49 const RefreshFrameInfo *const refresh_frame = &cpi->refresh_frame;
50
51 return frame_is_intra_only(cm) || cm->features.error_resilient_mode ||
52 refresh_frame->alt_ref_frame ||
53 (refresh_frame->golden_frame && !cpi->rc.is_src_frame_alt_ref);
54 }
55
56 // Segmentation only makes sense if the target bits per SB is above a threshold.
57 // Below this the overheads will usually outweigh any benefit.
is_sb_aq_enabled(const AV1_COMP * const cpi)58 static bool is_sb_aq_enabled(const AV1_COMP *const cpi) {
59 return cpi->rc.sb64_target_rate >= 256;
60 }
61
av1_setup_in_frame_q_adj(AV1_COMP * cpi)62 void av1_setup_in_frame_q_adj(AV1_COMP *cpi) {
63 AV1_COMMON *const cm = &cpi->common;
64 const int base_qindex = cm->quant_params.base_qindex;
65 struct segmentation *const seg = &cm->seg;
66 const int resolution_change =
67 cm->prev_frame && (cm->width != cm->prev_frame->width ||
68 cm->height != cm->prev_frame->height);
69
70 // Make SURE use of floating point in this function is safe.
71
72 if (resolution_change) {
73 memset(cpi->enc_seg.map, 0, cm->mi_params.mi_rows * cm->mi_params.mi_cols);
74 av1_clearall_segfeatures(seg);
75 av1_disable_segmentation(seg);
76 return;
77 }
78
79 if (is_frame_aq_enabled(cpi)) {
80 int segment;
81 const int aq_strength =
82 get_aq_c_strength(base_qindex, cm->seq_params->bit_depth);
83
84 // Clear down the segment map.
85 memset(cpi->enc_seg.map, DEFAULT_AQ2_SEG,
86 cm->mi_params.mi_rows * cm->mi_params.mi_cols);
87
88 av1_clearall_segfeatures(seg);
89
90 if (!is_sb_aq_enabled(cpi)) {
91 av1_disable_segmentation(seg);
92 return;
93 }
94
95 av1_enable_segmentation(seg);
96
97 // Default segment "Q" feature is disabled so it defaults to the baseline Q.
98 av1_disable_segfeature(seg, DEFAULT_AQ2_SEG, SEG_LVL_ALT_Q);
99
100 // Use some of the segments for in frame Q adjustment.
101 for (segment = 0; segment < AQ_C_SEGMENTS; ++segment) {
102 int qindex_delta;
103
104 if (segment == DEFAULT_AQ2_SEG) continue;
105
106 qindex_delta = av1_compute_qdelta_by_rate(
107 cpi, cm->current_frame.frame_type, base_qindex,
108 aq_c_q_adj_factor[aq_strength][segment]);
109
110 // For AQ complexity mode, we dont allow Q0 in a segment if the base
111 // Q is not 0. Q0 (lossless) implies 4x4 only and in AQ mode 2 a segment
112 // Q delta is sometimes applied without going back around the rd loop.
113 // This could lead to an illegal combination of partition size and q.
114 if ((base_qindex != 0) && ((base_qindex + qindex_delta) == 0)) {
115 qindex_delta = -base_qindex + 1;
116 }
117 if ((base_qindex + qindex_delta) > 0) {
118 av1_enable_segfeature(seg, segment, SEG_LVL_ALT_Q);
119 av1_set_segdata(seg, segment, SEG_LVL_ALT_Q, qindex_delta);
120 }
121 }
122 }
123 }
124
125 #define DEFAULT_LV_THRESH 10.0
126 #define MIN_DEFAULT_LV_THRESH 8.0
127 // Select a segment for the current block.
128 // The choice of segment for a block depends on the ratio of the projected
129 // 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)130 void av1_caq_select_segment(const AV1_COMP *cpi, MACROBLOCK *mb, BLOCK_SIZE bs,
131 int mi_row, int mi_col, int projected_rate) {
132 if ((!is_frame_aq_enabled(cpi)) || (!is_sb_aq_enabled(cpi))) return;
133 const AV1_COMMON *const cm = &cpi->common;
134 const int num_planes = av1_num_planes(cm);
135
136 const int mi_offset = mi_row * cm->mi_params.mi_cols + mi_col;
137 const int xmis = AOMMIN(cm->mi_params.mi_cols - mi_col, mi_size_wide[bs]);
138 const int ymis = AOMMIN(cm->mi_params.mi_rows - mi_row, mi_size_high[bs]);
139 int i;
140 unsigned char segment;
141
142 // Rate depends on fraction of a SB64 in frame (xmis * ymis / bw * bh).
143 // It is converted to bits << AV1_PROB_COST_SHIFT units.
144 const int64_t num = (int64_t)(cpi->rc.sb64_target_rate * xmis * ymis)
145 << AV1_PROB_COST_SHIFT;
146 const int denom = cm->seq_params->mib_size * cm->seq_params->mib_size;
147 const int target_rate = (int)(num / denom);
148 double logvar;
149 double low_var_thresh;
150 const int aq_strength = get_aq_c_strength(cm->quant_params.base_qindex,
151 cm->seq_params->bit_depth);
152
153 low_var_thresh =
154 (is_stat_consumption_stage_twopass(cpi))
155 ? AOMMAX(exp(cpi->twopass_frame.mb_av_energy), MIN_DEFAULT_LV_THRESH)
156 : DEFAULT_LV_THRESH;
157
158 av1_setup_src_planes(mb, cpi->source, mi_row, mi_col, num_planes, bs);
159 logvar = av1_log_block_var(cpi, mb, bs);
160
161 segment = AQ_C_SEGMENTS - 1; // Just in case no break out below.
162 for (i = 0; i < AQ_C_SEGMENTS; ++i) {
163 // Test rate against a threshold value and variance against a threshold.
164 // Increasing segment number (higher variance and complexity) = higher Q.
165 if ((projected_rate < target_rate * aq_c_transitions[aq_strength][i]) &&
166 (logvar < (low_var_thresh + aq_c_var_thresholds[aq_strength][i]))) {
167 segment = i;
168 break;
169 }
170 }
171
172 // Fill in the entires in the segment map corresponding to this SB64.
173 const int mi_stride = cm->mi_params.mi_cols;
174 set_segment_id(cpi->enc_seg.map, mi_offset, xmis, ymis, mi_stride, segment);
175 }
176