1 /*
2 * Copyright (c) 2010 The WebM project authors. All Rights Reserved.
3 *
4 * Use of this source code is governed by a BSD-style license
5 * that can be found in the LICENSE file in the root of the source
6 * tree. An additional intellectual property rights grant can be found
7 * in the file PATENTS. All contributing project authors may
8 * be found in the AUTHORS file in the root of the source tree.
9 */
10
11 #include <assert.h>
12 #include <limits.h>
13
14 #include "./vpx_scale_rtcd.h"
15
16 #include "vpx_mem/vpx_mem.h"
17
18 #include "vp9/common/vp9_loopfilter.h"
19 #include "vp9/common/vp9_onyxc_int.h"
20 #include "vp9/common/vp9_quant_common.h"
21
22 #include "vp9/encoder/vp9_onyx_int.h"
23 #include "vp9/encoder/vp9_picklpf.h"
24 #include "vp9/encoder/vp9_quantize.h"
25
get_max_filter_level(VP9_COMP * cpi)26 static int get_max_filter_level(VP9_COMP *cpi) {
27 return cpi->twopass.section_intra_rating > 8 ? MAX_LOOP_FILTER * 3 / 4
28 : MAX_LOOP_FILTER;
29 }
30
31
try_filter_frame(const YV12_BUFFER_CONFIG * sd,VP9_COMP * const cpi,int filt_level,int partial_frame)32 static int try_filter_frame(const YV12_BUFFER_CONFIG *sd, VP9_COMP *const cpi,
33 int filt_level, int partial_frame) {
34 VP9_COMMON *const cm = &cpi->common;
35 int filt_err;
36
37 vp9_loop_filter_frame(cm, &cpi->mb.e_mbd, filt_level, 1, partial_frame);
38 filt_err = vp9_calc_ss_err(sd, cm->frame_to_show);
39
40 // Re-instate the unfiltered frame
41 vpx_yv12_copy_y(&cpi->last_frame_uf, cm->frame_to_show);
42
43 return filt_err;
44 }
45
search_filter_level(const YV12_BUFFER_CONFIG * sd,VP9_COMP * cpi,int partial_frame)46 static void search_filter_level(const YV12_BUFFER_CONFIG *sd, VP9_COMP *cpi,
47 int partial_frame) {
48 VP9_COMMON *const cm = &cpi->common;
49 struct loopfilter *const lf = &cm->lf;
50 const int min_filter_level = 0;
51 const int max_filter_level = get_max_filter_level(cpi);
52 int best_err;
53 int filt_best;
54 int filt_direction = 0;
55 // Start the search at the previous frame filter level unless it is now out of
56 // range.
57 int filt_mid = clamp(lf->filter_level, min_filter_level, max_filter_level);
58 int filter_step = filt_mid < 16 ? 4 : filt_mid / 4;
59 // Sum squared error at each filter level
60 int ss_err[MAX_LOOP_FILTER + 1];
61
62 // Set each entry to -1
63 vpx_memset(ss_err, 0xFF, sizeof(ss_err));
64
65 // Make a copy of the unfiltered / processed recon buffer
66 vpx_yv12_copy_y(cm->frame_to_show, &cpi->last_frame_uf);
67
68 best_err = try_filter_frame(sd, cpi, filt_mid, partial_frame);
69 filt_best = filt_mid;
70 ss_err[filt_mid] = best_err;
71
72 while (filter_step > 0) {
73 const int filt_high = MIN(filt_mid + filter_step, max_filter_level);
74 const int filt_low = MAX(filt_mid - filter_step, min_filter_level);
75 int filt_err;
76
77 // Bias against raising loop filter in favor of lowering it.
78 int bias = (best_err >> (15 - (filt_mid / 8))) * filter_step;
79
80 if (cpi->twopass.section_intra_rating < 20)
81 bias = bias * cpi->twopass.section_intra_rating / 20;
82
83 // yx, bias less for large block size
84 if (cm->tx_mode != ONLY_4X4)
85 bias >>= 1;
86
87 if (filt_direction <= 0 && filt_low != filt_mid) {
88 // Get Low filter error score
89 if (ss_err[filt_low] < 0) {
90 filt_err = try_filter_frame(sd, cpi, filt_low, partial_frame);
91 ss_err[filt_low] = filt_err;
92 } else {
93 filt_err = ss_err[filt_low];
94 }
95 // If value is close to the best so far then bias towards a lower loop
96 // filter value.
97 if ((filt_err - bias) < best_err) {
98 // Was it actually better than the previous best?
99 if (filt_err < best_err)
100 best_err = filt_err;
101
102 filt_best = filt_low;
103 }
104 }
105
106 // Now look at filt_high
107 if (filt_direction >= 0 && filt_high != filt_mid) {
108 if (ss_err[filt_high] < 0) {
109 filt_err = try_filter_frame(sd, cpi, filt_high, partial_frame);
110 ss_err[filt_high] = filt_err;
111 } else {
112 filt_err = ss_err[filt_high];
113 }
114 // Was it better than the previous best?
115 if (filt_err < (best_err - bias)) {
116 best_err = filt_err;
117 filt_best = filt_high;
118 }
119 }
120
121 // Half the step distance if the best filter value was the same as last time
122 if (filt_best == filt_mid) {
123 filter_step /= 2;
124 filt_direction = 0;
125 } else {
126 filt_direction = (filt_best < filt_mid) ? -1 : 1;
127 filt_mid = filt_best;
128 }
129 }
130
131 lf->filter_level = filt_best;
132 }
133
vp9_pick_filter_level(const YV12_BUFFER_CONFIG * sd,VP9_COMP * cpi,LPF_PICK_METHOD method)134 void vp9_pick_filter_level(const YV12_BUFFER_CONFIG *sd, VP9_COMP *cpi,
135 LPF_PICK_METHOD method) {
136 VP9_COMMON *const cm = &cpi->common;
137 struct loopfilter *const lf = &cm->lf;
138
139 lf->sharpness_level = cm->frame_type == KEY_FRAME ? 0
140 : cpi->oxcf.sharpness;
141
142 if (method == LPF_PICK_FROM_Q) {
143 const int min_filter_level = 0;
144 const int max_filter_level = get_max_filter_level(cpi);
145 const int q = vp9_ac_quant(cm->base_qindex, 0);
146 // These values were determined by linear fitting the result of the
147 // searched level, filt_guess = q * 0.316206 + 3.87252
148 int filt_guess = ROUND_POWER_OF_TWO(q * 20723 + 1015158, 18);
149 if (cm->frame_type == KEY_FRAME)
150 filt_guess -= 4;
151 lf->filter_level = clamp(filt_guess, min_filter_level, max_filter_level);
152 } else {
153 search_filter_level(sd, cpi, method == LPF_PICK_FROM_SUBIMAGE);
154 }
155 }
156