// Copyright 2011 Google Inc. All Rights Reserved.
//
// 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 "./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 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) {
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