1 // Copyright 2011 Google Inc. All Rights Reserved.
2 //
3 // Use of this source code is governed by a BSD-style license
4 // that can be found in the COPYING file in the root of the source
5 // tree. An additional intellectual property rights grant can be found
6 // in the file PATENTS. All contributing project authors may
7 // be found in the AUTHORS file in the root of the source tree.
8 // -----------------------------------------------------------------------------
9 //
10 // Selecting filter level
11 //
12 // Author: somnath@google.com (Somnath Banerjee)
13
14 #include <assert.h>
15 #include "./vp8i_enc.h"
16 #include "../dsp/dsp.h"
17
18 // This table gives, for a given sharpness, the filtering strength to be
19 // used (at least) in order to filter a given edge step delta.
20 // This is constructed by brute force inspection: for all delta, we iterate
21 // over all possible filtering strength / thresh until needs_filter() returns
22 // true.
23 #define MAX_DELTA_SIZE 64
24 static const uint8_t kLevelsFromDelta[8][MAX_DELTA_SIZE] = {
25 { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
26 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31,
27 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47,
28 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63 },
29 { 0, 1, 2, 3, 5, 6, 7, 8, 9, 11, 12, 13, 14, 15, 17, 18,
30 20, 21, 23, 24, 26, 27, 29, 30, 32, 33, 35, 36, 38, 39, 41, 42,
31 44, 45, 47, 48, 50, 51, 53, 54, 56, 57, 59, 60, 62, 63, 63, 63,
32 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63 },
33 { 0, 1, 2, 3, 5, 6, 7, 8, 9, 11, 12, 13, 14, 16, 17, 19,
34 20, 22, 23, 25, 26, 28, 29, 31, 32, 34, 35, 37, 38, 40, 41, 43,
35 44, 46, 47, 49, 50, 52, 53, 55, 56, 58, 59, 61, 62, 63, 63, 63,
36 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63 },
37 { 0, 1, 2, 3, 5, 6, 7, 8, 9, 11, 12, 13, 15, 16, 18, 19,
38 21, 22, 24, 25, 27, 28, 30, 31, 33, 34, 36, 37, 39, 40, 42, 43,
39 45, 46, 48, 49, 51, 52, 54, 55, 57, 58, 60, 61, 63, 63, 63, 63,
40 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63 },
41 { 0, 1, 2, 3, 5, 6, 7, 8, 9, 11, 12, 14, 15, 17, 18, 20,
42 21, 23, 24, 26, 27, 29, 30, 32, 33, 35, 36, 38, 39, 41, 42, 44,
43 45, 47, 48, 50, 51, 53, 54, 56, 57, 59, 60, 62, 63, 63, 63, 63,
44 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63 },
45 { 0, 1, 2, 4, 5, 7, 8, 9, 11, 12, 13, 15, 16, 17, 19, 20,
46 22, 23, 25, 26, 28, 29, 31, 32, 34, 35, 37, 38, 40, 41, 43, 44,
47 46, 47, 49, 50, 52, 53, 55, 56, 58, 59, 61, 62, 63, 63, 63, 63,
48 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63 },
49 { 0, 1, 2, 4, 5, 7, 8, 9, 11, 12, 13, 15, 16, 18, 19, 21,
50 22, 24, 25, 27, 28, 30, 31, 33, 34, 36, 37, 39, 40, 42, 43, 45,
51 46, 48, 49, 51, 52, 54, 55, 57, 58, 60, 61, 63, 63, 63, 63, 63,
52 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63 },
53 { 0, 1, 2, 4, 5, 7, 8, 9, 11, 12, 14, 15, 17, 18, 20, 21,
54 23, 24, 26, 27, 29, 30, 32, 33, 35, 36, 38, 39, 41, 42, 44, 45,
55 47, 48, 50, 51, 53, 54, 56, 57, 59, 60, 62, 63, 63, 63, 63, 63,
56 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63 }
57 };
58
VP8FilterStrengthFromDelta(int sharpness,int delta)59 int VP8FilterStrengthFromDelta(int sharpness, int delta) {
60 const int pos = (delta < MAX_DELTA_SIZE) ? delta : MAX_DELTA_SIZE - 1;
61 assert(sharpness >= 0 && sharpness <= 7);
62 return kLevelsFromDelta[sharpness][pos];
63 }
64
65 //------------------------------------------------------------------------------
66 // Paragraph 15.4: compute the inner-edge filtering strength
67
GetILevel(int sharpness,int level)68 static int GetILevel(int sharpness, int level) {
69 if (sharpness > 0) {
70 if (sharpness > 4) {
71 level >>= 2;
72 } else {
73 level >>= 1;
74 }
75 if (level > 9 - sharpness) {
76 level = 9 - sharpness;
77 }
78 }
79 if (level < 1) level = 1;
80 return level;
81 }
82
DoFilter(const VP8EncIterator * const it,int level)83 static void DoFilter(const VP8EncIterator* const it, int level) {
84 const VP8Encoder* const enc = it->enc_;
85 const int ilevel = GetILevel(enc->config_->filter_sharpness, level);
86 const int limit = 2 * level + ilevel;
87
88 uint8_t* const y_dst = it->yuv_out2_ + Y_OFF_ENC;
89 uint8_t* const u_dst = it->yuv_out2_ + U_OFF_ENC;
90 uint8_t* const v_dst = it->yuv_out2_ + V_OFF_ENC;
91
92 // copy current block to yuv_out2_
93 memcpy(y_dst, it->yuv_out_, YUV_SIZE_ENC * sizeof(uint8_t));
94
95 if (enc->filter_hdr_.simple_ == 1) { // simple
96 VP8SimpleHFilter16i(y_dst, BPS, limit);
97 VP8SimpleVFilter16i(y_dst, BPS, limit);
98 } else { // complex
99 const int hev_thresh = (level >= 40) ? 2 : (level >= 15) ? 1 : 0;
100 VP8HFilter16i(y_dst, BPS, limit, ilevel, hev_thresh);
101 VP8HFilter8i(u_dst, v_dst, BPS, limit, ilevel, hev_thresh);
102 VP8VFilter16i(y_dst, BPS, limit, ilevel, hev_thresh);
103 VP8VFilter8i(u_dst, v_dst, BPS, limit, ilevel, hev_thresh);
104 }
105 }
106
107 //------------------------------------------------------------------------------
108 // SSIM metric for one macroblock
109
GetMBSSIM(const uint8_t * yuv1,const uint8_t * yuv2)110 static double GetMBSSIM(const uint8_t* yuv1, const uint8_t* yuv2) {
111 int x, y;
112 double sum = 0.;
113
114 // compute SSIM in a 10 x 10 window
115 for (y = VP8_SSIM_KERNEL; y < 16 - VP8_SSIM_KERNEL; y++) {
116 for (x = VP8_SSIM_KERNEL; x < 16 - VP8_SSIM_KERNEL; x++) {
117 sum += VP8SSIMGetClipped(yuv1 + Y_OFF_ENC, BPS, yuv2 + Y_OFF_ENC, BPS,
118 x, y, 16, 16);
119 }
120 }
121 for (x = 1; x < 7; x++) {
122 for (y = 1; y < 7; y++) {
123 sum += VP8SSIMGetClipped(yuv1 + U_OFF_ENC, BPS, yuv2 + U_OFF_ENC, BPS,
124 x, y, 8, 8);
125 sum += VP8SSIMGetClipped(yuv1 + V_OFF_ENC, BPS, yuv2 + V_OFF_ENC, BPS,
126 x, y, 8, 8);
127 }
128 }
129 return sum;
130 }
131
132 //------------------------------------------------------------------------------
133 // Exposed APIs: Encoder should call the following 3 functions to adjust
134 // loop filter strength
135
VP8InitFilter(VP8EncIterator * const it)136 void VP8InitFilter(VP8EncIterator* const it) {
137 if (it->lf_stats_ != NULL) {
138 int s, i;
139 for (s = 0; s < NUM_MB_SEGMENTS; s++) {
140 for (i = 0; i < MAX_LF_LEVELS; i++) {
141 (*it->lf_stats_)[s][i] = 0;
142 }
143 }
144 VP8SSIMDspInit();
145 }
146 }
147
VP8StoreFilterStats(VP8EncIterator * const it)148 void VP8StoreFilterStats(VP8EncIterator* const it) {
149 int d;
150 VP8Encoder* const enc = it->enc_;
151 const int s = it->mb_->segment_;
152 const int level0 = enc->dqm_[s].fstrength_;
153
154 // explore +/-quant range of values around level0
155 const int delta_min = -enc->dqm_[s].quant_;
156 const int delta_max = enc->dqm_[s].quant_;
157 const int step_size = (delta_max - delta_min >= 4) ? 4 : 1;
158
159 if (it->lf_stats_ == NULL) return;
160
161 // NOTE: Currently we are applying filter only across the sublock edges
162 // There are two reasons for that.
163 // 1. Applying filter on macro block edges will change the pixels in
164 // the left and top macro blocks. That will be hard to restore
165 // 2. Macro Blocks on the bottom and right are not yet compressed. So we
166 // cannot apply filter on the right and bottom macro block edges.
167 if (it->mb_->type_ == 1 && it->mb_->skip_) return;
168
169 // Always try filter level zero
170 (*it->lf_stats_)[s][0] += GetMBSSIM(it->yuv_in_, it->yuv_out_);
171
172 for (d = delta_min; d <= delta_max; d += step_size) {
173 const int level = level0 + d;
174 if (level <= 0 || level >= MAX_LF_LEVELS) {
175 continue;
176 }
177 DoFilter(it, level);
178 (*it->lf_stats_)[s][level] += GetMBSSIM(it->yuv_in_, it->yuv_out2_);
179 }
180 }
181
VP8AdjustFilterStrength(VP8EncIterator * const it)182 void VP8AdjustFilterStrength(VP8EncIterator* const it) {
183 VP8Encoder* const enc = it->enc_;
184 if (it->lf_stats_ != NULL) {
185 int s;
186 for (s = 0; s < NUM_MB_SEGMENTS; s++) {
187 int i, best_level = 0;
188 // Improvement over filter level 0 should be at least 1e-5 (relatively)
189 double best_v = 1.00001 * (*it->lf_stats_)[s][0];
190 for (i = 1; i < MAX_LF_LEVELS; i++) {
191 const double v = (*it->lf_stats_)[s][i];
192 if (v > best_v) {
193 best_v = v;
194 best_level = i;
195 }
196 }
197 enc->dqm_[s].fstrength_ = best_level;
198 }
199 } else if (enc->config_->filter_strength > 0) {
200 int max_level = 0;
201 int s;
202 for (s = 0; s < NUM_MB_SEGMENTS; s++) {
203 VP8SegmentInfo* const dqm = &enc->dqm_[s];
204 // this '>> 3' accounts for some inverse WHT scaling
205 const int delta = (dqm->max_edge_ * dqm->y2_.q_[1]) >> 3;
206 const int level =
207 VP8FilterStrengthFromDelta(enc->filter_hdr_.sharpness_, delta);
208 if (level > dqm->fstrength_) {
209 dqm->fstrength_ = level;
210 }
211 if (max_level < dqm->fstrength_) {
212 max_level = dqm->fstrength_;
213 }
214 }
215 enc->filter_hdr_.level_ = max_level;
216 }
217 }
218
219 // -----------------------------------------------------------------------------
220