// Copyright 2011 Google Inc. All Rights Reserved. // // Use of this source code is governed by a BSD-style license // that can be found in the COPYING file in the root of the source // tree. An additional intellectual property rights grant can be found // in the file PATENTS. All contributing project authors may // be found in the AUTHORS file in the root of the source tree. // ----------------------------------------------------------------------------- // // Selecting filter level // // Author: somnath@google.com (Somnath Banerjee) #include #include "./vp8enci.h" // This table gives, for a given sharpness, the filtering strength to be // used (at least) in order to filter a given edge step delta. // This is constructed by brute force inspection: for all delta, we iterate // over all possible filtering strength / thresh until needs_filter() returns // true. #define MAX_DELTA_SIZE 64 static const uint8_t kLevelsFromDelta[8][MAX_DELTA_SIZE] = { { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63 }, { 0, 1, 2, 3, 5, 6, 7, 8, 9, 11, 12, 13, 14, 15, 17, 18, 20, 21, 23, 24, 26, 27, 29, 30, 32, 33, 35, 36, 38, 39, 41, 42, 44, 45, 47, 48, 50, 51, 53, 54, 56, 57, 59, 60, 62, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63 }, { 0, 1, 2, 3, 5, 6, 7, 8, 9, 11, 12, 13, 14, 16, 17, 19, 20, 22, 23, 25, 26, 28, 29, 31, 32, 34, 35, 37, 38, 40, 41, 43, 44, 46, 47, 49, 50, 52, 53, 55, 56, 58, 59, 61, 62, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63 }, { 0, 1, 2, 3, 5, 6, 7, 8, 9, 11, 12, 13, 15, 16, 18, 19, 21, 22, 24, 25, 27, 28, 30, 31, 33, 34, 36, 37, 39, 40, 42, 43, 45, 46, 48, 49, 51, 52, 54, 55, 57, 58, 60, 61, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63 }, { 0, 1, 2, 3, 5, 6, 7, 8, 9, 11, 12, 14, 15, 17, 18, 20, 21, 23, 24, 26, 27, 29, 30, 32, 33, 35, 36, 38, 39, 41, 42, 44, 45, 47, 48, 50, 51, 53, 54, 56, 57, 59, 60, 62, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63 }, { 0, 1, 2, 4, 5, 7, 8, 9, 11, 12, 13, 15, 16, 17, 19, 20, 22, 23, 25, 26, 28, 29, 31, 32, 34, 35, 37, 38, 40, 41, 43, 44, 46, 47, 49, 50, 52, 53, 55, 56, 58, 59, 61, 62, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63 }, { 0, 1, 2, 4, 5, 7, 8, 9, 11, 12, 13, 15, 16, 18, 19, 21, 22, 24, 25, 27, 28, 30, 31, 33, 34, 36, 37, 39, 40, 42, 43, 45, 46, 48, 49, 51, 52, 54, 55, 57, 58, 60, 61, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63 }, { 0, 1, 2, 4, 5, 7, 8, 9, 11, 12, 14, 15, 17, 18, 20, 21, 23, 24, 26, 27, 29, 30, 32, 33, 35, 36, 38, 39, 41, 42, 44, 45, 47, 48, 50, 51, 53, 54, 56, 57, 59, 60, 62, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63, 63 } }; int VP8FilterStrengthFromDelta(int sharpness, int delta) { const int pos = (delta < MAX_DELTA_SIZE) ? delta : MAX_DELTA_SIZE - 1; assert(sharpness >= 0 && sharpness <= 7); return kLevelsFromDelta[sharpness][pos]; } // ----------------------------------------------------------------------------- // NOTE: clip1, tables and InitTables are repeated entries of dsp.c static uint8_t abs0[255 + 255 + 1]; // abs(i) static uint8_t abs1[255 + 255 + 1]; // abs(i)>>1 static int8_t sclip1[1020 + 1020 + 1]; // clips [-1020, 1020] to [-128, 127] static int8_t sclip2[112 + 112 + 1]; // clips [-112, 112] to [-16, 15] static uint8_t clip1[255 + 510 + 1]; // clips [-255,510] to [0,255] static int tables_ok = 0; static void InitTables(void) { if (!tables_ok) { int i; for (i = -255; i <= 255; ++i) { abs0[255 + i] = (i < 0) ? -i : i; abs1[255 + i] = abs0[255 + i] >> 1; } for (i = -1020; i <= 1020; ++i) { sclip1[1020 + i] = (i < -128) ? -128 : (i > 127) ? 127 : i; } for (i = -112; i <= 112; ++i) { sclip2[112 + i] = (i < -16) ? -16 : (i > 15) ? 15 : i; } for (i = -255; i <= 255 + 255; ++i) { clip1[255 + i] = (i < 0) ? 0 : (i > 255) ? 255 : i; } tables_ok = 1; } } //------------------------------------------------------------------------------ // Edge filtering functions // 4 pixels in, 2 pixels out static WEBP_INLINE void do_filter2(uint8_t* p, int step) { const int p1 = p[-2*step], p0 = p[-step], q0 = p[0], q1 = p[step]; const int a = 3 * (q0 - p0) + sclip1[1020 + p1 - q1]; const int a1 = sclip2[112 + ((a + 4) >> 3)]; const int a2 = sclip2[112 + ((a + 3) >> 3)]; p[-step] = clip1[255 + p0 + a2]; p[ 0] = clip1[255 + q0 - a1]; } // 4 pixels in, 4 pixels out static WEBP_INLINE void do_filter4(uint8_t* p, int step) { const int p1 = p[-2*step], p0 = p[-step], q0 = p[0], q1 = p[step]; const int a = 3 * (q0 - p0); const int a1 = sclip2[112 + ((a + 4) >> 3)]; const int a2 = sclip2[112 + ((a + 3) >> 3)]; const int a3 = (a1 + 1) >> 1; p[-2*step] = clip1[255 + p1 + a3]; p[- step] = clip1[255 + p0 + a2]; p[ 0] = clip1[255 + q0 - a1]; p[ step] = clip1[255 + q1 - a3]; } // high edge-variance static WEBP_INLINE int hev(const uint8_t* p, int step, int thresh) { const int p1 = p[-2*step], p0 = p[-step], q0 = p[0], q1 = p[step]; return (abs0[255 + p1 - p0] > thresh) || (abs0[255 + q1 - q0] > thresh); } static WEBP_INLINE int needs_filter(const uint8_t* p, int step, int thresh) { const int p1 = p[-2*step], p0 = p[-step], q0 = p[0], q1 = p[step]; return (2 * abs0[255 + p0 - q0] + abs1[255 + p1 - q1]) <= thresh; } static WEBP_INLINE int needs_filter2(const uint8_t* p, int step, int t, int it) { const int p3 = p[-4*step], p2 = p[-3*step], p1 = p[-2*step], p0 = p[-step]; const int q0 = p[0], q1 = p[step], q2 = p[2*step], q3 = p[3*step]; if ((2 * abs0[255 + p0 - q0] + abs1[255 + p1 - q1]) > t) return 0; return abs0[255 + p3 - p2] <= it && abs0[255 + p2 - p1] <= it && abs0[255 + p1 - p0] <= it && abs0[255 + q3 - q2] <= it && abs0[255 + q2 - q1] <= it && abs0[255 + q1 - q0] <= it; } //------------------------------------------------------------------------------ // Simple In-loop filtering (Paragraph 15.2) static void SimpleVFilter16(uint8_t* p, int stride, int thresh) { int i; for (i = 0; i < 16; ++i) { if (needs_filter(p + i, stride, thresh)) { do_filter2(p + i, stride); } } } static void SimpleHFilter16(uint8_t* p, int stride, int thresh) { int i; for (i = 0; i < 16; ++i) { if (needs_filter(p + i * stride, 1, thresh)) { do_filter2(p + i * stride, 1); } } } static void SimpleVFilter16i(uint8_t* p, int stride, int thresh) { int k; for (k = 3; k > 0; --k) { p += 4 * stride; SimpleVFilter16(p, stride, thresh); } } static void SimpleHFilter16i(uint8_t* p, int stride, int thresh) { int k; for (k = 3; k > 0; --k) { p += 4; SimpleHFilter16(p, stride, thresh); } } //------------------------------------------------------------------------------ // Complex In-loop filtering (Paragraph 15.3) static WEBP_INLINE void FilterLoop24(uint8_t* p, int hstride, int vstride, int size, int thresh, int ithresh, int hev_thresh) { while (size-- > 0) { if (needs_filter2(p, hstride, thresh, ithresh)) { if (hev(p, hstride, hev_thresh)) { do_filter2(p, hstride); } else { do_filter4(p, hstride); } } p += vstride; } } // on three inner edges static void VFilter16i(uint8_t* p, int stride, int thresh, int ithresh, int hev_thresh) { int k; for (k = 3; k > 0; --k) { p += 4 * stride; FilterLoop24(p, stride, 1, 16, thresh, ithresh, hev_thresh); } } static void HFilter16i(uint8_t* p, int stride, int thresh, int ithresh, int hev_thresh) { int k; for (k = 3; k > 0; --k) { p += 4; FilterLoop24(p, 1, stride, 16, thresh, ithresh, hev_thresh); } } static void VFilter8i(uint8_t* u, uint8_t* v, int stride, int thresh, int ithresh, int hev_thresh) { FilterLoop24(u + 4 * stride, stride, 1, 8, thresh, ithresh, hev_thresh); FilterLoop24(v + 4 * stride, stride, 1, 8, thresh, ithresh, hev_thresh); } static void HFilter8i(uint8_t* u, uint8_t* v, int stride, int thresh, int ithresh, int hev_thresh) { FilterLoop24(u + 4, 1, stride, 8, thresh, ithresh, hev_thresh); FilterLoop24(v + 4, 1, stride, 8, thresh, ithresh, hev_thresh); } //------------------------------------------------------------------------------ void (*VP8EncVFilter16i)(uint8_t*, int, int, int, int) = VFilter16i; void (*VP8EncHFilter16i)(uint8_t*, int, int, int, int) = HFilter16i; void (*VP8EncVFilter8i)(uint8_t*, uint8_t*, int, int, int, int) = VFilter8i; void (*VP8EncHFilter8i)(uint8_t*, uint8_t*, int, int, int, int) = HFilter8i; void (*VP8EncSimpleVFilter16i)(uint8_t*, int, int) = SimpleVFilter16i; void (*VP8EncSimpleHFilter16i)(uint8_t*, int, int) = SimpleHFilter16i; //------------------------------------------------------------------------------ // Paragraph 15.4: compute the inner-edge filtering strength static int GetILevel(int sharpness, int level) { if (sharpness > 0) { if (sharpness > 4) { level >>= 2; } else { level >>= 1; } if (level > 9 - sharpness) { level = 9 - sharpness; } } if (level < 1) level = 1; return level; } static void DoFilter(const VP8EncIterator* const it, int level) { const VP8Encoder* const enc = it->enc_; const int ilevel = GetILevel(enc->config_->filter_sharpness, level); const int limit = 2 * level + ilevel; uint8_t* const y_dst = it->yuv_out2_ + Y_OFF; uint8_t* const u_dst = it->yuv_out2_ + U_OFF; uint8_t* const v_dst = it->yuv_out2_ + V_OFF; // copy current block to yuv_out2_ memcpy(y_dst, it->yuv_out_, YUV_SIZE * sizeof(uint8_t)); if (enc->filter_hdr_.simple_ == 1) { // simple VP8EncSimpleHFilter16i(y_dst, BPS, limit); VP8EncSimpleVFilter16i(y_dst, BPS, limit); } else { // complex const int hev_thresh = (level >= 40) ? 2 : (level >= 15) ? 1 : 0; VP8EncHFilter16i(y_dst, BPS, limit, ilevel, hev_thresh); VP8EncHFilter8i(u_dst, v_dst, BPS, limit, ilevel, hev_thresh); VP8EncVFilter16i(y_dst, BPS, limit, ilevel, hev_thresh); VP8EncVFilter8i(u_dst, v_dst, BPS, limit, ilevel, hev_thresh); } } //------------------------------------------------------------------------------ // SSIM metric enum { KERNEL = 3 }; static const double kMinValue = 1.e-10; // minimal threshold void VP8SSIMAddStats(const DistoStats* const src, DistoStats* const dst) { dst->w += src->w; dst->xm += src->xm; dst->ym += src->ym; dst->xxm += src->xxm; dst->xym += src->xym; dst->yym += src->yym; } static void VP8SSIMAccumulate(const uint8_t* src1, int stride1, const uint8_t* src2, int stride2, int xo, int yo, int W, int H, DistoStats* const stats) { const int ymin = (yo - KERNEL < 0) ? 0 : yo - KERNEL; const int ymax = (yo + KERNEL > H - 1) ? H - 1 : yo + KERNEL; const int xmin = (xo - KERNEL < 0) ? 0 : xo - KERNEL; const int xmax = (xo + KERNEL > W - 1) ? W - 1 : xo + KERNEL; int x, y; src1 += ymin * stride1; src2 += ymin * stride2; for (y = ymin; y <= ymax; ++y, src1 += stride1, src2 += stride2) { for (x = xmin; x <= xmax; ++x) { const int s1 = src1[x]; const int s2 = src2[x]; stats->w += 1; stats->xm += s1; stats->ym += s2; stats->xxm += s1 * s1; stats->xym += s1 * s2; stats->yym += s2 * s2; } } } double VP8SSIMGet(const DistoStats* const stats) { const double xmxm = stats->xm * stats->xm; const double ymym = stats->ym * stats->ym; const double xmym = stats->xm * stats->ym; const double w2 = stats->w * stats->w; double sxx = stats->xxm * stats->w - xmxm; double syy = stats->yym * stats->w - ymym; double sxy = stats->xym * stats->w - xmym; double C1, C2; double fnum; double fden; // small errors are possible, due to rounding. Clamp to zero. if (sxx < 0.) sxx = 0.; if (syy < 0.) syy = 0.; C1 = 6.5025 * w2; C2 = 58.5225 * w2; fnum = (2 * xmym + C1) * (2 * sxy + C2); fden = (xmxm + ymym + C1) * (sxx + syy + C2); return (fden != 0.) ? fnum / fden : kMinValue; } double VP8SSIMGetSquaredError(const DistoStats* const s) { if (s->w > 0.) { const double iw2 = 1. / (s->w * s->w); const double sxx = s->xxm * s->w - s->xm * s->xm; const double syy = s->yym * s->w - s->ym * s->ym; const double sxy = s->xym * s->w - s->xm * s->ym; const double SSE = iw2 * (sxx + syy - 2. * sxy); if (SSE > kMinValue) return SSE; } return kMinValue; } void VP8SSIMAccumulatePlane(const uint8_t* src1, int stride1, const uint8_t* src2, int stride2, int W, int H, DistoStats* const stats) { int x, y; for (y = 0; y < H; ++y) { for (x = 0; x < W; ++x) { VP8SSIMAccumulate(src1, stride1, src2, stride2, x, y, W, H, stats); } } } static double GetMBSSIM(const uint8_t* yuv1, const uint8_t* yuv2) { int x, y; DistoStats s = { .0, .0, .0, .0, .0, .0 }; // compute SSIM in a 10 x 10 window for (x = 3; x < 13; x++) { for (y = 3; y < 13; y++) { VP8SSIMAccumulate(yuv1 + Y_OFF, BPS, yuv2 + Y_OFF, BPS, x, y, 16, 16, &s); } } for (x = 1; x < 7; x++) { for (y = 1; y < 7; y++) { VP8SSIMAccumulate(yuv1 + U_OFF, BPS, yuv2 + U_OFF, BPS, x, y, 8, 8, &s); VP8SSIMAccumulate(yuv1 + V_OFF, BPS, yuv2 + V_OFF, BPS, x, y, 8, 8, &s); } } return VP8SSIMGet(&s); } //------------------------------------------------------------------------------ // Exposed APIs: Encoder should call the following 3 functions to adjust // loop filter strength void VP8InitFilter(VP8EncIterator* const it) { if (it->lf_stats_ != NULL) { int s, i; InitTables(); for (s = 0; s < NUM_MB_SEGMENTS; s++) { for (i = 0; i < MAX_LF_LEVELS; i++) { (*it->lf_stats_)[s][i] = 0; } } } } void VP8StoreFilterStats(VP8EncIterator* const it) { int d; VP8Encoder* const enc = it->enc_; const int s = it->mb_->segment_; const int level0 = enc->dqm_[s].fstrength_; // TODO: ref_lf_delta[] // explore +/-quant range of values around level0 const int delta_min = -enc->dqm_[s].quant_; const int delta_max = enc->dqm_[s].quant_; const int step_size = (delta_max - delta_min >= 4) ? 4 : 1; if (it->lf_stats_ == NULL) return; // NOTE: Currently we are applying filter only across the sublock edges // There are two reasons for that. // 1. Applying filter on macro block edges will change the pixels in // the left and top macro blocks. That will be hard to restore // 2. Macro Blocks on the bottom and right are not yet compressed. So we // cannot apply filter on the right and bottom macro block edges. if (it->mb_->type_ == 1 && it->mb_->skip_) return; // Always try filter level zero (*it->lf_stats_)[s][0] += GetMBSSIM(it->yuv_in_, it->yuv_out_); for (d = delta_min; d <= delta_max; d += step_size) { const int level = level0 + d; if (level <= 0 || level >= MAX_LF_LEVELS) { continue; } DoFilter(it, level); (*it->lf_stats_)[s][level] += GetMBSSIM(it->yuv_in_, it->yuv_out2_); } } void VP8AdjustFilterStrength(VP8EncIterator* const it) { VP8Encoder* const enc = it->enc_; if (it->lf_stats_ != NULL) { int s; for (s = 0; s < NUM_MB_SEGMENTS; s++) { int i, best_level = 0; // Improvement over filter level 0 should be at least 1e-5 (relatively) double best_v = 1.00001 * (*it->lf_stats_)[s][0]; for (i = 1; i < MAX_LF_LEVELS; i++) { const double v = (*it->lf_stats_)[s][i]; if (v > best_v) { best_v = v; best_level = i; } } enc->dqm_[s].fstrength_ = best_level; } } else if (enc->config_->filter_strength > 0) { int max_level = 0; int s; for (s = 0; s < NUM_MB_SEGMENTS; s++) { VP8SegmentInfo* const dqm = &enc->dqm_[s]; // this '>> 3' accounts for some inverse WHT scaling const int delta = (dqm->max_edge_ * dqm->y2_.q_[1]) >> 3; const int level = VP8FilterStrengthFromDelta(enc->filter_hdr_.sharpness_, delta); if (level > dqm->fstrength_) { dqm->fstrength_ = level; } if (max_level < dqm->fstrength_) { max_level = dqm->fstrength_; } } enc->filter_hdr_.level_ = max_level; } } // -----------------------------------------------------------------------------