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-rw-r--r--src/enc/filter.c378
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diff --git a/src/enc/filter.c b/src/enc/filter.c
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+// Copyright 2011 Google Inc.
+//
+// This code is licensed under the same terms as WebM:
+// Software License Agreement: http://www.webmproject.org/license/software/
+// Additional IP Rights Grant: http://www.webmproject.org/license/additional/
+// -----------------------------------------------------------------------------
+//
+// Selecting filter level
+//
+// Author: somnath@google.com (Somnath Banerjee)
+
+#include <math.h>
+#include "vp8enci.h"
+
+#if defined(__cplusplus) || defined(c_plusplus)
+extern "C" {
+#endif
+
+// 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 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 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 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 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 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 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 };
+typedef struct {
+ double w, xm, ym, xxm, xym, yym;
+} SSIMStats;
+
+static void Accumulate(const uint8_t* src1, int stride1,
+ const uint8_t* src2, int stride2,
+ int xo, int yo, int W, int H,
+ SSIMStats* 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;
+ }
+ }
+}
+
+static double GetSSIM(const SSIMStats* 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 : 0.;
+}
+
+static double GetMBSSIM(const uint8_t* yuv1, const uint8_t* yuv2) {
+ int x, y;
+ SSIMStats 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++) {
+ Accumulate(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++) {
+ Accumulate(yuv1 + U_OFF, BPS, yuv2 + U_OFF, BPS, x, y, 8, 8, &s);
+ Accumulate(yuv1 + V_OFF, BPS, yuv2 + V_OFF, BPS, x, y, 8, 8, &s);
+ }
+ }
+ return GetSSIM(&s);
+}
+
+//-----------------------------------------------------------------------------
+// Exposed APIs: Encoder should call the following 3 functions to adjust
+// loop filter strength
+
+void VP8InitFilter(VP8EncIterator* const it) {
+ int s, i;
+ if (!it->lf_stats_) return;
+
+ 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;
+ const int s = it->mb_->segment_;
+ const int level0 = it->enc_->dqm_[s].fstrength_; // TODO: ref_lf_delta[]
+
+ // explore +/-quant range of values around level0
+ const int delta_min = -it->enc_->dqm_[s].quant_;
+ const int delta_max = it->enc_->dqm_[s].quant_;
+ const int step_size = (delta_max - delta_min >= 4) ? 4 : 1;
+
+ if (!it->lf_stats_) 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) {
+ int s;
+ VP8Encoder* const enc = it->enc_;
+
+ if (!it->lf_stats_) {
+ return;
+ }
+ 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;
+ }
+}
+
+#if defined(__cplusplus) || defined(c_plusplus)
+} // extern "C"
+#endif
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