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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