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_encoder.h"
23 #include "vp9/encoder/vp9_picklpf.h"
24 #include "vp9/encoder/vp9_quantize.h"
25
get_max_filter_level(const VP9_COMP * cpi)26 static int get_max_filter_level(const VP9_COMP *cpi) {
27 if (cpi->oxcf.pass == 2) {
28 return cpi->twopass.section_intra_rating > 8 ? MAX_LOOP_FILTER * 3 / 4
29 : MAX_LOOP_FILTER;
30 } else {
31 return MAX_LOOP_FILTER;
32 }
33 }
34
35
try_filter_frame(const YV12_BUFFER_CONFIG * sd,VP9_COMP * const cpi,int filt_level,int partial_frame)36 static int try_filter_frame(const YV12_BUFFER_CONFIG *sd, VP9_COMP *const cpi,
37 int filt_level, int partial_frame) {
38 VP9_COMMON *const cm = &cpi->common;
39 int filt_err;
40
41 vp9_loop_filter_frame(cm->frame_to_show, cm, &cpi->mb.e_mbd, filt_level, 1,
42 partial_frame);
43 filt_err = vp9_get_y_sse(sd, cm->frame_to_show);
44
45 // Re-instate the unfiltered frame
46 vpx_yv12_copy_y(&cpi->last_frame_uf, cm->frame_to_show);
47
48 return filt_err;
49 }
50
search_filter_level(const YV12_BUFFER_CONFIG * sd,VP9_COMP * cpi,int partial_frame)51 static int search_filter_level(const YV12_BUFFER_CONFIG *sd, VP9_COMP *cpi,
52 int partial_frame) {
53 const VP9_COMMON *const cm = &cpi->common;
54 const struct loopfilter *const lf = &cm->lf;
55 const int min_filter_level = 0;
56 const int max_filter_level = get_max_filter_level(cpi);
57 int filt_direction = 0;
58 int best_err, filt_best;
59
60 // Start the search at the previous frame filter level unless it is now out of
61 // range.
62 int filt_mid = clamp(lf->filter_level, min_filter_level, max_filter_level);
63 int filter_step = filt_mid < 16 ? 4 : filt_mid / 4;
64 // Sum squared error at each filter level
65 int ss_err[MAX_LOOP_FILTER + 1];
66
67 // Set each entry to -1
68 vpx_memset(ss_err, 0xFF, sizeof(ss_err));
69
70 // Make a copy of the unfiltered / processed recon buffer
71 vpx_yv12_copy_y(cm->frame_to_show, &cpi->last_frame_uf);
72
73 best_err = try_filter_frame(sd, cpi, filt_mid, partial_frame);
74 filt_best = filt_mid;
75 ss_err[filt_mid] = best_err;
76
77 while (filter_step > 0) {
78 const int filt_high = MIN(filt_mid + filter_step, max_filter_level);
79 const int filt_low = MAX(filt_mid - filter_step, min_filter_level);
80
81 // Bias against raising loop filter in favor of lowering it.
82 int bias = (best_err >> (15 - (filt_mid / 8))) * filter_step;
83
84 if ((cpi->oxcf.pass == 2) && (cpi->twopass.section_intra_rating < 20))
85 bias = (bias * cpi->twopass.section_intra_rating) / 20;
86
87 // yx, bias less for large block size
88 if (cm->tx_mode != ONLY_4X4)
89 bias >>= 1;
90
91 if (filt_direction <= 0 && filt_low != filt_mid) {
92 // Get Low filter error score
93 if (ss_err[filt_low] < 0) {
94 ss_err[filt_low] = try_filter_frame(sd, cpi, filt_low, partial_frame);
95 }
96 // If value is close to the best so far then bias towards a lower loop
97 // filter value.
98 if ((ss_err[filt_low] - bias) < best_err) {
99 // Was it actually better than the previous best?
100 if (ss_err[filt_low] < best_err)
101 best_err = ss_err[filt_low];
102
103 filt_best = filt_low;
104 }
105 }
106
107 // Now look at filt_high
108 if (filt_direction >= 0 && filt_high != filt_mid) {
109 if (ss_err[filt_high] < 0) {
110 ss_err[filt_high] = try_filter_frame(sd, cpi, filt_high, partial_frame);
111 }
112 // Was it better than the previous best?
113 if (ss_err[filt_high] < (best_err - bias)) {
114 best_err = ss_err[filt_high];
115 filt_best = filt_high;
116 }
117 }
118
119 // Half the step distance if the best filter value was the same as last time
120 if (filt_best == filt_mid) {
121 filter_step /= 2;
122 filt_direction = 0;
123 } else {
124 filt_direction = (filt_best < filt_mid) ? -1 : 1;
125 filt_mid = filt_best;
126 }
127 }
128
129 return filt_best;
130 }
131
vp9_pick_filter_level(const YV12_BUFFER_CONFIG * sd,VP9_COMP * cpi,LPF_PICK_METHOD method)132 void vp9_pick_filter_level(const YV12_BUFFER_CONFIG *sd, VP9_COMP *cpi,
133 LPF_PICK_METHOD method) {
134 VP9_COMMON *const cm = &cpi->common;
135 struct loopfilter *const lf = &cm->lf;
136
137 lf->sharpness_level = cm->frame_type == KEY_FRAME ? 0
138 : cpi->oxcf.sharpness;
139
140 if (method == LPF_PICK_MINIMAL_LPF && lf->filter_level) {
141 lf->filter_level = 0;
142 } else 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, cm->bit_depth);
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 lf->filter_level = search_filter_level(sd, cpi,
154 method == LPF_PICK_FROM_SUBIMAGE);
155 }
156 }
157