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 (at) google.com (Somnath Banerjee) 13 14 #include <assert.h> 15 #include "./vp8enci.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 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 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 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 109 110 enum { KERNEL = 3 }; 111 static const double kMinValue = 1.e-10; // minimal threshold 112 113 void VP8SSIMAddStats(const DistoStats* const src, DistoStats* const dst) { 114 dst->w += src->w; 115 dst->xm += src->xm; 116 dst->ym += src->ym; 117 dst->xxm += src->xxm; 118 dst->xym += src->xym; 119 dst->yym += src->yym; 120 } 121 122 static void VP8SSIMAccumulate(const uint8_t* src1, int stride1, 123 const uint8_t* src2, int stride2, 124 int xo, int yo, int W, int H, 125 DistoStats* const stats) { 126 const int ymin = (yo - KERNEL < 0) ? 0 : yo - KERNEL; 127 const int ymax = (yo + KERNEL > H - 1) ? H - 1 : yo + KERNEL; 128 const int xmin = (xo - KERNEL < 0) ? 0 : xo - KERNEL; 129 const int xmax = (xo + KERNEL > W - 1) ? W - 1 : xo + KERNEL; 130 int x, y; 131 src1 += ymin * stride1; 132 src2 += ymin * stride2; 133 for (y = ymin; y <= ymax; ++y, src1 += stride1, src2 += stride2) { 134 for (x = xmin; x <= xmax; ++x) { 135 const int s1 = src1[x]; 136 const int s2 = src2[x]; 137 stats->w += 1; 138 stats->xm += s1; 139 stats->ym += s2; 140 stats->xxm += s1 * s1; 141 stats->xym += s1 * s2; 142 stats->yym += s2 * s2; 143 } 144 } 145 } 146 147 double VP8SSIMGet(const DistoStats* const stats) { 148 const double xmxm = stats->xm * stats->xm; 149 const double ymym = stats->ym * stats->ym; 150 const double xmym = stats->xm * stats->ym; 151 const double w2 = stats->w * stats->w; 152 double sxx = stats->xxm * stats->w - xmxm; 153 double syy = stats->yym * stats->w - ymym; 154 double sxy = stats->xym * stats->w - xmym; 155 double C1, C2; 156 double fnum; 157 double fden; 158 // small errors are possible, due to rounding. Clamp to zero. 159 if (sxx < 0.) sxx = 0.; 160 if (syy < 0.) syy = 0.; 161 C1 = 6.5025 * w2; 162 C2 = 58.5225 * w2; 163 fnum = (2 * xmym + C1) * (2 * sxy + C2); 164 fden = (xmxm + ymym + C1) * (sxx + syy + C2); 165 return (fden != 0.) ? fnum / fden : kMinValue; 166 } 167 168 double VP8SSIMGetSquaredError(const DistoStats* const s) { 169 if (s->w > 0.) { 170 const double iw2 = 1. / (s->w * s->w); 171 const double sxx = s->xxm * s->w - s->xm * s->xm; 172 const double syy = s->yym * s->w - s->ym * s->ym; 173 const double sxy = s->xym * s->w - s->xm * s->ym; 174 const double SSE = iw2 * (sxx + syy - 2. * sxy); 175 if (SSE > kMinValue) return SSE; 176 } 177 return kMinValue; 178 } 179 180 void VP8SSIMAccumulatePlane(const uint8_t* src1, int stride1, 181 const uint8_t* src2, int stride2, 182 int W, int H, DistoStats* const stats) { 183 int x, y; 184 for (y = 0; y < H; ++y) { 185 for (x = 0; x < W; ++x) { 186 VP8SSIMAccumulate(src1, stride1, src2, stride2, x, y, W, H, stats); 187 } 188 } 189 } 190 191 static double GetMBSSIM(const uint8_t* yuv1, const uint8_t* yuv2) { 192 int x, y; 193 DistoStats s = { .0, .0, .0, .0, .0, .0 }; 194 195 // compute SSIM in a 10 x 10 window 196 for (x = 3; x < 13; x++) { 197 for (y = 3; y < 13; y++) { 198 VP8SSIMAccumulate(yuv1 + Y_OFF_ENC, BPS, yuv2 + Y_OFF_ENC, BPS, 199 x, y, 16, 16, &s); 200 } 201 } 202 for (x = 1; x < 7; x++) { 203 for (y = 1; y < 7; y++) { 204 VP8SSIMAccumulate(yuv1 + U_OFF_ENC, BPS, yuv2 + U_OFF_ENC, BPS, 205 x, y, 8, 8, &s); 206 VP8SSIMAccumulate(yuv1 + V_OFF_ENC, BPS, yuv2 + V_OFF_ENC, BPS, 207 x, y, 8, 8, &s); 208 } 209 } 210 return VP8SSIMGet(&s); 211 } 212 213 //------------------------------------------------------------------------------ 214 // Exposed APIs: Encoder should call the following 3 functions to adjust 215 // loop filter strength 216 217 void VP8InitFilter(VP8EncIterator* const it) { 218 if (it->lf_stats_ != NULL) { 219 int s, i; 220 for (s = 0; s < NUM_MB_SEGMENTS; s++) { 221 for (i = 0; i < MAX_LF_LEVELS; i++) { 222 (*it->lf_stats_)[s][i] = 0; 223 } 224 } 225 } 226 } 227 228 void VP8StoreFilterStats(VP8EncIterator* const it) { 229 int d; 230 VP8Encoder* const enc = it->enc_; 231 const int s = it->mb_->segment_; 232 const int level0 = enc->dqm_[s].fstrength_; 233 234 // explore +/-quant range of values around level0 235 const int delta_min = -enc->dqm_[s].quant_; 236 const int delta_max = enc->dqm_[s].quant_; 237 const int step_size = (delta_max - delta_min >= 4) ? 4 : 1; 238 239 if (it->lf_stats_ == NULL) return; 240 241 // NOTE: Currently we are applying filter only across the sublock edges 242 // There are two reasons for that. 243 // 1. Applying filter on macro block edges will change the pixels in 244 // the left and top macro blocks. That will be hard to restore 245 // 2. Macro Blocks on the bottom and right are not yet compressed. So we 246 // cannot apply filter on the right and bottom macro block edges. 247 if (it->mb_->type_ == 1 && it->mb_->skip_) return; 248 249 // Always try filter level zero 250 (*it->lf_stats_)[s][0] += GetMBSSIM(it->yuv_in_, it->yuv_out_); 251 252 for (d = delta_min; d <= delta_max; d += step_size) { 253 const int level = level0 + d; 254 if (level <= 0 || level >= MAX_LF_LEVELS) { 255 continue; 256 } 257 DoFilter(it, level); 258 (*it->lf_stats_)[s][level] += GetMBSSIM(it->yuv_in_, it->yuv_out2_); 259 } 260 } 261 262 void VP8AdjustFilterStrength(VP8EncIterator* const it) { 263 VP8Encoder* const enc = it->enc_; 264 if (it->lf_stats_ != NULL) { 265 int s; 266 for (s = 0; s < NUM_MB_SEGMENTS; s++) { 267 int i, best_level = 0; 268 // Improvement over filter level 0 should be at least 1e-5 (relatively) 269 double best_v = 1.00001 * (*it->lf_stats_)[s][0]; 270 for (i = 1; i < MAX_LF_LEVELS; i++) { 271 const double v = (*it->lf_stats_)[s][i]; 272 if (v > best_v) { 273 best_v = v; 274 best_level = i; 275 } 276 } 277 enc->dqm_[s].fstrength_ = best_level; 278 } 279 } else if (enc->config_->filter_strength > 0) { 280 int max_level = 0; 281 int s; 282 for (s = 0; s < NUM_MB_SEGMENTS; s++) { 283 VP8SegmentInfo* const dqm = &enc->dqm_[s]; 284 // this '>> 3' accounts for some inverse WHT scaling 285 const int delta = (dqm->max_edge_ * dqm->y2_.q_[1]) >> 3; 286 const int level = 287 VP8FilterStrengthFromDelta(enc->filter_hdr_.sharpness_, delta); 288 if (level > dqm->fstrength_) { 289 dqm->fstrength_ = level; 290 } 291 if (max_level < dqm->fstrength_) { 292 max_level = dqm->fstrength_; 293 } 294 } 295 enc->filter_hdr_.level_ = max_level; 296 } 297 } 298 299 // ----------------------------------------------------------------------------- 300
