xref: /aosp_15_r20/external/libaom/av1/encoder/aq_complexity.c (revision 77c1e3ccc04c968bd2bc212e87364f250e820521)
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