// 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.
// -----------------------------------------------------------------------------
//
// Speed-critical encoding functions.
//
// Author: Skal (pascal.massimino@gmail.com)
#include <assert.h>
#include <stdlib.h> // for abs()
#include "./dsp.h"
#include "../enc/vp8i_enc.h"
static WEBP_INLINE uint8_t clip_8b(int v) {
return (!(v & ~0xff)) ? v : (v < 0) ? 0 : 255;
}
static WEBP_INLINE int clip_max(int v, int max) {
return (v > max) ? max : v;
}
//------------------------------------------------------------------------------
// Compute susceptibility based on DCT-coeff histograms:
// the higher, the "easier" the macroblock is to compress.
const int VP8DspScan[16 + 4 + 4] = {
// Luma
0 + 0 * BPS, 4 + 0 * BPS, 8 + 0 * BPS, 12 + 0 * BPS,
0 + 4 * BPS, 4 + 4 * BPS, 8 + 4 * BPS, 12 + 4 * BPS,
0 + 8 * BPS, 4 + 8 * BPS, 8 + 8 * BPS, 12 + 8 * BPS,
0 + 12 * BPS, 4 + 12 * BPS, 8 + 12 * BPS, 12 + 12 * BPS,
0 + 0 * BPS, 4 + 0 * BPS, 0 + 4 * BPS, 4 + 4 * BPS, // U
8 + 0 * BPS, 12 + 0 * BPS, 8 + 4 * BPS, 12 + 4 * BPS // V
};
// general-purpose util function
void VP8SetHistogramData(const int distribution[MAX_COEFF_THRESH + 1],
VP8Histogram* const histo) {
int max_value = 0, last_non_zero = 1;
int k;
for (k = 0; k <= MAX_COEFF_THRESH; ++k) {
const int value = distribution[k];
if (value > 0) {
if (value > max_value) max_value = value;
last_non_zero = k;
}
}
histo->max_value = max_value;
histo->last_non_zero = last_non_zero;
}
static void CollectHistogram(const uint8_t* ref, const uint8_t* pred,
int start_block, int end_block,
VP8Histogram* const histo) {
int j;
int distribution[MAX_COEFF_THRESH + 1] = { 0 };
for (j = start_block; j < end_block; ++j) {
int k;
int16_t out[16];
VP8FTransform(ref + VP8DspScan[j], pred + VP8DspScan[j], out);
// Convert coefficients to bin.
for (k = 0; k < 16; ++k) {
const int v = abs(out[k]) >> 3;
const int clipped_value = clip_max(v, MAX_COEFF_THRESH);
++distribution[clipped_value];
}
}
VP8SetHistogramData(distribution, histo);
}
//------------------------------------------------------------------------------
// run-time tables (~4k)
static uint8_t clip1[255 + 510 + 1]; // clips [-255,510] to [0,255]
// We declare this variable 'volatile' to prevent instruction reordering
// and make sure it's set to true _last_ (so as to be thread-safe)
static volatile int tables_ok = 0;
static WEBP_TSAN_IGNORE_FUNCTION void InitTables(void) {
if (!tables_ok) {
int i;
for (i = -255; i <= 255 + 255; ++i) {
clip1[255 + i] = clip_8b(i);
}
tables_ok = 1;
}
}
//------------------------------------------------------------------------------
// Transforms (Paragraph 14.4)
#define STORE(x, y, v) \
dst[(x) + (y) * BPS] = clip_8b(ref[(x) + (y) * BPS] + ((v) >> 3))
static const int kC1 = 20091 + (1 << 16);
static const int kC2 = 35468;
#define MUL(a, b) (((a) * (b)) >> 16)
static WEBP_INLINE void ITransformOne(const uint8_t* ref, const int16_t* in,
uint8_t* dst) {
int C[4 * 4], *tmp;
int i;
tmp = C;
for (i = 0; i < 4; ++i) { // vertical pass
const int a = in[0] + in[8];
const int b = in[0] - in[8];
const int c = MUL(in[4], kC2) - MUL(in[12], kC1);
const int d = MUL(in[4], kC1) + MUL(in[12], kC2);
tmp[0] = a + d;
tmp[1] = b + c;
tmp[2] = b - c;
tmp[3] = a - d;
tmp += 4;
in++;
}
tmp = C;
for (i = 0; i < 4; ++i) { // horizontal pass
const int dc = tmp[0] + 4;
const int a = dc + tmp[8];
const int b = dc - tmp[8];
const int c = MUL(tmp[4], kC2) - MUL(tmp[12], kC1);
const int d = MUL(tmp[4], kC1) + MUL(tmp[12], kC2);
STORE(0, i, a + d);
STORE(1, i, b + c);
STORE(2, i, b - c);
STORE(3, i, a - d);
tmp++;
}
}
static void ITransform(const uint8_t* ref, const int16_t* in, uint8_t* dst,
int do_two) {
ITransformOne(ref, in, dst);
if (do_two) {
ITransformOne(ref + 4, in + 16, dst + 4);
}
}
static void FTransform(const uint8_t* src, const uint8_t* ref, int16_t* out) {
int i;
int tmp[16];
for (i = 0; i < 4; ++i, src += BPS, ref += BPS) {
const int d0 = src[0] - ref[0]; // 9bit dynamic range ([-255,255])
const int d1 = src[1] - ref[1];
const int d2 = src[2] - ref[2];
const int d3 = src[3] - ref[3];
const int a0 = (d0 + d3); // 10b [-510,510]
const int a1 = (d1 + d2);
const int a2 = (d1 - d2);
const int a3 = (d0 - d3);
tmp[0 + i * 4] = (a0 + a1) * 8; // 14b [-8160,8160]
tmp[1 + i * 4] = (a2 * 2217 + a3 * 5352 + 1812) >> 9; // [-7536,7542]
tmp[2 + i * 4] = (a0 - a1) * 8;
tmp[3 + i * 4] = (a3 * 2217 - a2 * 5352 + 937) >> 9;
}
for (i = 0; i < 4; ++i) {
const int a0 = (tmp[0 + i] + tmp[12 + i]); // 15b
const int a1 = (tmp[4 + i] + tmp[ 8 + i]);
const int a2 = (tmp[4 + i] - tmp[ 8 + i]);
const int a3 = (tmp[0 + i] - tmp[12 + i]);
out[0 + i] = (a0 + a1 + 7) >> 4; // 12b
out[4 + i] = ((a2 * 2217 + a3 * 5352 + 12000) >> 16) + (a3 != 0);
out[8 + i] = (a0 - a1 + 7) >> 4;
out[12+ i] = ((a3 * 2217 - a2 * 5352 + 51000) >> 16);
}
}
static void FTransform2(const uint8_t* src, const uint8_t* ref, int16_t* out) {
VP8FTransform(src, ref, out);
VP8FTransform(src + 4, ref + 4, out + 16);
}
static void FTransformWHT(const int16_t* in, int16_t* out) {
// input is 12b signed
int32_t tmp[16];
int i;
for (i = 0; i < 4; ++i, in += 64) {
const int a0 = (in[0 * 16] + in[2 * 16]); // 13b
const int a1 = (in[1 * 16] + in[3 * 16]);
const int a2 = (in[1 * 16] - in[3 * 16]);
const int a3 = (in[0 * 16] - in[2 * 16]);
tmp[0 + i * 4] = a0 + a1; // 14b
tmp[1 + i * 4] = a3 + a2;
tmp[2 + i * 4] = a3 - a2;
tmp[3 + i * 4] = a0 - a1;
}
for (i = 0; i < 4; ++i) {
const int a0 = (tmp[0 + i] + tmp[8 + i]); // 15b
const int a1 = (tmp[4 + i] + tmp[12+ i]);
const int a2 = (tmp[4 + i] - tmp[12+ i]);
const int a3 = (tmp[0 + i] - tmp[8 + i]);
const int b0 = a0 + a1; // 16b
const int b1 = a3 + a2;
const int b2 = a3 - a2;
const int b3 = a0 - a1;
out[ 0 + i] = b0 >> 1; // 15b
out[ 4 + i] = b1 >> 1;
out[ 8 + i] = b2 >> 1;
out[12 + i] = b3 >> 1;
}
}
#undef MUL
#undef STORE
//------------------------------------------------------------------------------
// Intra predictions
static WEBP_INLINE void Fill(uint8_t* dst, int value, int size) {
int j;
for (j = 0; j < size; ++j) {
memset(dst + j * BPS, value, size);
}
}
static WEBP_INLINE void VerticalPred(uint8_t* dst,
const uint8_t* top, int size) {
int j;
if (top != NULL) {
for (j = 0; j < size; ++j) memcpy(dst + j * BPS, top, size);
} else {
Fill(dst, 127, size);
}
}
static WEBP_INLINE void HorizontalPred(uint8_t* dst,
const uint8_t* left, int size) {
if (left != NULL) {
int j;
for (j = 0; j < size; ++j) {
memset(dst + j * BPS, left[j], size);
}
} else {
Fill(dst, 129, size);
}
}
static WEBP_INLINE void TrueMotion(uint8_t* dst, const uint8_t* left,
const uint8_t* top, int size) {
int y;
if (left != NULL) {
if (top != NULL) {
const uint8_t* const clip = clip1 + 255 - left[-1];
for (y = 0; y < size; ++y) {
const uint8_t* const clip_table = clip + left[y];
int x;
for (x = 0; x < size; ++x) {
dst[x] = clip_table[top[x]];
}
dst += BPS;
}
} else {
HorizontalPred(dst, left, size);
}
} else {
// true motion without left samples (hence: with default 129 value)
// is equivalent to VE prediction where you just copy the top samples.
// Note that if top samples are not available, the default value is
// then 129, and not 127 as in the VerticalPred case.
if (top != NULL) {
VerticalPred(dst, top, size);
} else {
Fill(dst, 129, size);
}
}
}
static WEBP_INLINE void DCMode(uint8_t* dst, const uint8_t* left,
const uint8_t* top,
int size, int round, int shift) {
int DC = 0;
int j;
if (top != NULL) {
for (j = 0; j < size; ++j) DC += top[j];
if (left != NULL) { // top and left present
for (j = 0; j < size; ++j) DC += left[j];
} else { // top, but no left
DC += DC;
}
DC = (DC + round) >> shift;
} else if (left != NULL) { // left but no top
for (j = 0; j < size; ++j) DC += left[j];
DC += DC;
DC = (DC + round) >> shift;
} else { // no top, no left, nothing.
DC = 0x80;
}
Fill(dst, DC, size);
}
//------------------------------------------------------------------------------
// Chroma 8x8 prediction (paragraph 12.2)
static void IntraChromaPreds(uint8_t* dst, const uint8_t* left,
const uint8_t* top) {
// U block
DCMode(C8DC8 + dst, left, top, 8, 8, 4);
VerticalPred(C8VE8 + dst, top, 8);
HorizontalPred(C8HE8 + dst, left, 8);
TrueMotion(C8TM8 + dst, left, top, 8);
// V block
dst += 8;
if (top != NULL) top += 8;
if (left != NULL) left += 16;
DCMode(C8DC8 + dst, left, top, 8, 8, 4);
VerticalPred(C8VE8 + dst, top, 8);
HorizontalPred(C8HE8 + dst, left, 8);
TrueMotion(C8TM8 + dst, left, top, 8);
}
//------------------------------------------------------------------------------
// luma 16x16 prediction (paragraph 12.3)
static void Intra16Preds(uint8_t* dst,
const uint8_t* left, const uint8_t* top) {
DCMode(I16DC16 + dst, left, top, 16, 16, 5);
VerticalPred(I16VE16 + dst, top, 16);
HorizontalPred(I16HE16 + dst, left, 16);
TrueMotion(I16TM16 + dst, left, top, 16);
}
//------------------------------------------------------------------------------
// luma 4x4 prediction
#define DST(x, y) dst[(x) + (y) * BPS]
#define AVG3(a, b, c) ((uint8_t)(((a) + 2 * (b) + (c) + 2) >> 2))
#define AVG2(a, b) (((a) + (b) + 1) >> 1)
static void VE4(uint8_t* dst, const uint8_t* top) { // vertical
const uint8_t vals[4] = {
AVG3(top[-1], top[0], top[1]),
AVG3(top[ 0], top[1], top[2]),
AVG3(top[ 1], top[2], top[3]),
AVG3(top[ 2], top[3], top[4])
};
int i;
for (i = 0; i < 4; ++i) {
memcpy(dst + i * BPS, vals, 4);
}
}
static void HE4(uint8_t* dst, const uint8_t* top) { // horizontal
const int X = top[-1];
const int I = top[-2];
const int J = top[-3];
const int K = top[-4];
const int L = top[-5];
WebPUint32ToMem(dst + 0 * BPS, 0x01010101U * AVG3(X, I, J));
WebPUint32ToMem(dst + 1 * BPS, 0x01010101U * AVG3(I, J, K));
WebPUint32ToMem(dst + 2 * BPS, 0x01010101U * AVG3(J, K, L));
WebPUint32ToMem(dst + 3 * BPS, 0x01010101U * AVG3(K, L, L));
}
static void DC4(uint8_t* dst, const uint8_t* top) {
uint32_t dc = 4;
int i;
for (i = 0; i < 4; ++i) dc += top[i] + top[-5 + i];
Fill(dst, dc >> 3, 4);
}
static void RD4(uint8_t* dst, const uint8_t* top) {
const int X = top[-1];
const int I = top[-2];
const int J = top[-3];
const int K = top[-4];
const int L = top[-5];
const int A = top[0];
const int B = top[1];
const int C = top[2];
const int D = top[3];
DST(0, 3) = AVG3(J, K, L);
DST(0, 2) = DST(1, 3) = AVG3(I, J, K);
DST(0, 1) = DST(1, 2) = DST(2, 3) = AVG3(X, I, J);
DST(0, 0) = DST(1, 1) = DST(2, 2) = DST(3, 3) = AVG3(A, X, I);
DST(1, 0) = DST(2, 1) = DST(3, 2) = AVG3(B, A, X);
DST(2, 0) = DST(3, 1) = AVG3(C, B, A);
DST(3, 0) = AVG3(D, C, B);
}
static void LD4(uint8_t* dst, const uint8_t* top) {
const int A = top[0];
const int B = top[1];
const int C = top[2];
const int D = top[3];
const int E = top[4];
const int F = top[5];
const int G = top[6];
const int H = top[7];
DST(0, 0) = AVG3(A, B, C);
DST(1, 0) = DST(0, 1) = AVG3(B, C, D);
DST(2, 0) = DST(1, 1) = DST(0, 2) = AVG3(C, D, E);
DST(3, 0) = DST(2, 1) = DST(1, 2) = DST(0, 3) = AVG3(D, E, F);
DST(3, 1) = DST(2, 2) = DST(1, 3) = AVG3(E, F, G);
DST(3, 2) = DST(2, 3) = AVG3(F, G, H);
DST(3, 3) = AVG3(G, H, H);
}
static void VR4(uint8_t* dst, const uint8_t* top) {
const int X = top[-1];
const int I = top[-2];
const int J = top[-3];
const int K = top[-4];
const int A = top[0];
const int B = top[1];
const int C = top[2];
const int D = top[3];
DST(0, 0) = DST(1, 2) = AVG2(X, A);
DST(1, 0) = DST(2, 2) = AVG2(A, B);
DST(2, 0) = DST(3, 2) = AVG2(B, C);
DST(3, 0) = AVG2(C, D);
DST(0, 3) = AVG3(K, J, I);
DST(0, 2) = AVG3(J, I, X);
DST(0, 1) = DST(1, 3) = AVG3(I, X, A);
DST(1, 1) = DST(2, 3) = AVG3(X, A, B);
DST(2, 1) = DST(3, 3) = AVG3(A, B, C);
DST(3, 1) = AVG3(B, C, D);
}
static void VL4(uint8_t* dst, const uint8_t* top) {
const int A = top[0];
const int B = top[1];
const int C = top[2];
const int D = top[3];
const int E = top[4];
const int F = top[5];
const int G = top[6];
const int H = top[7];
DST(0, 0) = AVG2(A, B);
DST(1, 0) = DST(0, 2) = AVG2(B, C);
DST(2, 0) = DST(1, 2) = AVG2(C, D);
DST(3, 0) = DST(2, 2) = AVG2(D, E);
DST(0, 1) = AVG3(A, B, C);
DST(1, 1) = DST(0, 3) = AVG3(B, C, D);
DST(2, 1) = DST(1, 3) = AVG3(C, D, E);
DST(3, 1) = DST(2, 3) = AVG3(D, E, F);
DST(3, 2) = AVG3(E, F, G);
DST(3, 3) = AVG3(F, G, H);
}
static void HU4(uint8_t* dst, const uint8_t* top) {
const int I = top[-2];
const int J = top[-3];
const int K = top[-4];
const int L = top[-5];
DST(0, 0) = AVG2(I, J);
DST(2, 0) = DST(0, 1) = AVG2(J, K);
DST(2, 1) = DST(0, 2) = AVG2(K, L);
DST(1, 0) = AVG3(I, J, K);
DST(3, 0) = DST(1, 1) = AVG3(J, K, L);
DST(3, 1) = DST(1, 2) = AVG3(K, L, L);
DST(3, 2) = DST(2, 2) =
DST(0, 3) = DST(1, 3) = DST(2, 3) = DST(3, 3) = L;
}
static void HD4(uint8_t* dst, const uint8_t* top) {
const int X = top[-1];
const int I = top[-2];
const int J = top[-3];
const int K = top[-4];
const int L = top[-5];
const int A = top[0];
const int B = top[1];
const int C = top[2];
DST(0, 0) = DST(2, 1) = AVG2(I, X);
DST(0, 1) = DST(2, 2) = AVG2(J, I);
DST(0, 2) = DST(2, 3) = AVG2(K, J);
DST(0, 3) = AVG2(L, K);
DST(3, 0) = AVG3(A, B, C);
DST(2, 0) = AVG3(X, A, B);
DST(1, 0) = DST(3, 1) = AVG3(I, X, A);
DST(1, 1) = DST(3, 2) = AVG3(J, I, X);
DST(1, 2) = DST(3, 3) = AVG3(K, J, I);
DST(1, 3) = AVG3(L, K, J);
}
static void TM4(uint8_t* dst, const uint8_t* top) {
int x, y;
const uint8_t* const clip = clip1 + 255 - top[-1];
for (y = 0; y < 4; ++y) {
const uint8_t* const clip_table = clip + top[-2 - y];
for (x = 0; x < 4; ++x) {
dst[x] = clip_table[top[x]];
}
dst += BPS;
}
}
#undef DST
#undef AVG3
#undef AVG2
// Left samples are top[-5 .. -2], top_left is top[-1], top are
// located at top[0..3], and top right is top[4..7]
static void Intra4Preds(uint8_t* dst, const uint8_t* top) {
DC4(I4DC4 + dst, top);
TM4(I4TM4 + dst, top);
VE4(I4VE4 + dst, top);
HE4(I4HE4 + dst, top);
RD4(I4RD4 + dst, top);
VR4(I4VR4 + dst, top);
LD4(I4LD4 + dst, top);
VL4(I4VL4 + dst, top);
HD4(I4HD4 + dst, top);
HU4(I4HU4 + dst, top);
}
//------------------------------------------------------------------------------
// Metric
static WEBP_INLINE int GetSSE(const uint8_t* a, const uint8_t* b,
int w, int h) {
int count = 0;
int y, x;
for (y = 0; y < h; ++y) {
for (x = 0; x < w; ++x) {
const int diff = (int)a[x] - b[x];
count += diff * diff;
}
a += BPS;
b += BPS;
}
return count;
}
static int SSE16x16(const uint8_t* a, const uint8_t* b) {
return GetSSE(a, b, 16, 16);
}
static int SSE16x8(const uint8_t* a, const uint8_t* b) {
return GetSSE(a, b, 16, 8);
}
static int SSE8x8(const uint8_t* a, const uint8_t* b) {
return GetSSE(a, b, 8, 8);
}
static int SSE4x4(const uint8_t* a, const uint8_t* b) {
return GetSSE(a, b, 4, 4);
}
static void Mean16x4(const uint8_t* ref, uint32_t dc[4]) {
int k, x, y;
for (k = 0; k < 4; ++k) {
uint32_t avg = 0;
for (y = 0; y < 4; ++y) {
for (x = 0; x < 4; ++x) {
avg += ref[x + y * BPS];
}
}
dc[k] = avg;
ref += 4; // go to next 4x4 block.
}
}
//------------------------------------------------------------------------------
// Texture distortion
//
// We try to match the spectral content (weighted) between source and
// reconstructed samples.
// Hadamard transform
// Returns the weighted sum of the absolute value of transformed coefficients.
// w[] contains a row-major 4 by 4 symmetric matrix.
static int TTransform(const uint8_t* in, const uint16_t* w) {
int sum = 0;
int tmp[16];
int i;
// horizontal pass
for (i = 0; i < 4; ++i, in += BPS) {
const int a0 = in[0] + in[2];
const int a1 = in[1] + in[3];
const int a2 = in[1] - in[3];
const int a3 = in[0] - in[2];
tmp[0 + i * 4] = a0 + a1;
tmp[1 + i * 4] = a3 + a2;
tmp[2 + i * 4] = a3 - a2;
tmp[3 + i * 4] = a0 - a1;
}
// vertical pass
for (i = 0; i < 4; ++i, ++w) {
const int a0 = tmp[0 + i] + tmp[8 + i];
const int a1 = tmp[4 + i] + tmp[12+ i];
const int a2 = tmp[4 + i] - tmp[12+ i];
const int a3 = tmp[0 + i] - tmp[8 + i];
const int b0 = a0 + a1;
const int b1 = a3 + a2;
const int b2 = a3 - a2;
const int b3 = a0 - a1;
sum += w[ 0] * abs(b0);
sum += w[ 4] * abs(b1);
sum += w[ 8] * abs(b2);
sum += w[12] * abs(b3);
}
return sum;
}
static int Disto4x4(const uint8_t* const a, const uint8_t* const b,
const uint16_t* const w) {
const int sum1 = TTransform(a, w);
const int sum2 = TTransform(b, w);
return abs(sum2 - sum1) >> 5;
}
static int Disto16x16(const uint8_t* const a, const uint8_t* const b,
const uint16_t* const w) {
int D = 0;
int x, y;
for (y = 0; y < 16 * BPS; y += 4 * BPS) {
for (x = 0; x < 16; x += 4) {
D += Disto4x4(a + x + y, b + x + y, w);
}
}
return D;
}
//------------------------------------------------------------------------------
// Quantization
//
static const uint8_t kZigzag[16] = {
0, 1, 4, 8, 5, 2, 3, 6, 9, 12, 13, 10, 7, 11, 14, 15
};
// Simple quantization
static int QuantizeBlock(int16_t in[16], int16_t out[16],
const VP8Matrix* const mtx) {
int last = -1;
int n;
for (n = 0; n < 16; ++n) {
const int j = kZigzag[n];
const int sign = (in[j] < 0);
const uint32_t coeff = (sign ? -in[j] : in[j]) + mtx->sharpen_[j];
if (coeff > mtx->zthresh_[j]) {
const uint32_t Q = mtx->q_[j];
const uint32_t iQ = mtx->iq_[j];
const uint32_t B = mtx->bias_[j];
int level = QUANTDIV(coeff, iQ, B);
if (level > MAX_LEVEL) level = MAX_LEVEL;
if (sign) level = -level;
in[j] = level * (int)Q;
out[n] = level;
if (level) last = n;
} else {
out[n] = 0;
in[j] = 0;
}
}
return (last >= 0);
}
static int Quantize2Blocks(int16_t in[32], int16_t out[32],
const VP8Matrix* const mtx) {
int nz;
nz = VP8EncQuantizeBlock(in + 0 * 16, out + 0 * 16, mtx) << 0;
nz |= VP8EncQuantizeBlock(in + 1 * 16, out + 1 * 16, mtx) << 1;
return nz;
}
//------------------------------------------------------------------------------
// Block copy
static WEBP_INLINE void Copy(const uint8_t* src, uint8_t* dst, int w, int h) {
int y;
for (y = 0; y < h; ++y) {
memcpy(dst, src, w);
src += BPS;
dst += BPS;
}
}
static void Copy4x4(const uint8_t* src, uint8_t* dst) {
Copy(src, dst, 4, 4);
}
static void Copy16x8(const uint8_t* src, uint8_t* dst) {
Copy(src, dst, 16, 8);
}
//------------------------------------------------------------------------------
// SSIM / PSNR
// hat-shaped filter. Sum of coefficients is equal to 16.
static const uint32_t kWeight[2 * VP8_SSIM_KERNEL + 1] = {
1, 2, 3, 4, 3, 2, 1
};
static const uint32_t kWeightSum = 16 * 16; // sum{kWeight}^2
static WEBP_INLINE double SSIMCalculation(
const VP8DistoStats* const stats, uint32_t N /*num samples*/) {
const uint32_t w2 = N * N;
const uint32_t C1 = 20 * w2;
const uint32_t C2 = 60 * w2;
const uint32_t C3 = 8 * 8 * w2; // 'dark' limit ~= 6
const uint64_t xmxm = (uint64_t)stats->xm * stats->xm;
const uint64_t ymym = (uint64_t)stats->ym * stats->ym;
if (xmxm + ymym >= C3) {
const int64_t xmym = (int64_t)stats->xm * stats->ym;
const int64_t sxy = (int64_t)stats->xym * N - xmym; // can be negative
const uint64_t sxx = (uint64_t)stats->xxm * N - xmxm;
const uint64_t syy = (uint64_t)stats->yym * N - ymym;
// we descale by 8 to prevent overflow during the fnum/fden multiply.
const uint64_t num_S = (2 * (uint64_t)(sxy < 0 ? 0 : sxy) + C2) >> 8;
const uint64_t den_S = (sxx + syy + C2) >> 8;
const uint64_t fnum = (2 * xmym + C1) * num_S;
const uint64_t fden = (xmxm + ymym + C1) * den_S;
const double r = (double)fnum / fden;
assert(r >= 0. && r <= 1.0);
return r;
}
return 1.; // area is too dark to contribute meaningfully
}
double VP8SSIMFromStats(const VP8DistoStats* const stats) {
return SSIMCalculation(stats, kWeightSum);
}
double VP8SSIMFromStatsClipped(const VP8DistoStats* const stats) {
return SSIMCalculation(stats, stats->w);
}
static double SSIMGetClipped_C(const uint8_t* src1, int stride1,
const uint8_t* src2, int stride2,
int xo, int yo, int W, int H) {
VP8DistoStats stats = { 0, 0, 0, 0, 0, 0 };
const int ymin = (yo - VP8_SSIM_KERNEL < 0) ? 0 : yo - VP8_SSIM_KERNEL;
const int ymax = (yo + VP8_SSIM_KERNEL > H - 1) ? H - 1
: yo + VP8_SSIM_KERNEL;
const int xmin = (xo - VP8_SSIM_KERNEL < 0) ? 0 : xo - VP8_SSIM_KERNEL;
const int xmax = (xo + VP8_SSIM_KERNEL > W - 1) ? W - 1
: xo + VP8_SSIM_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 uint32_t w = kWeight[VP8_SSIM_KERNEL + x - xo]
* kWeight[VP8_SSIM_KERNEL + y - yo];
const uint32_t s1 = src1[x];
const uint32_t s2 = src2[x];
stats.w += w;
stats.xm += w * s1;
stats.ym += w * s2;
stats.xxm += w * s1 * s1;
stats.xym += w * s1 * s2;
stats.yym += w * s2 * s2;
}
}
return VP8SSIMFromStatsClipped(&stats);
}
static double SSIMGet_C(const uint8_t* src1, int stride1,
const uint8_t* src2, int stride2) {
VP8DistoStats stats = { 0, 0, 0, 0, 0, 0 };
int x, y;
for (y = 0; y <= 2 * VP8_SSIM_KERNEL; ++y, src1 += stride1, src2 += stride2) {
for (x = 0; x <= 2 * VP8_SSIM_KERNEL; ++x) {
const uint32_t w = kWeight[x] * kWeight[y];
const uint32_t s1 = src1[x];
const uint32_t s2 = src2[x];
stats.xm += w * s1;
stats.ym += w * s2;
stats.xxm += w * s1 * s1;
stats.xym += w * s1 * s2;
stats.yym += w * s2 * s2;
}
}
return VP8SSIMFromStats(&stats);
}
//------------------------------------------------------------------------------
static uint32_t AccumulateSSE(const uint8_t* src1,
const uint8_t* src2, int len) {
int i;
uint32_t sse2 = 0;
assert(len <= 65535); // to ensure that accumulation fits within uint32_t
for (i = 0; i < len; ++i) {
const int32_t diff = src1[i] - src2[i];
sse2 += diff * diff;
}
return sse2;
}
//------------------------------------------------------------------------------
VP8SSIMGetFunc VP8SSIMGet;
VP8SSIMGetClippedFunc VP8SSIMGetClipped;
VP8AccumulateSSEFunc VP8AccumulateSSE;
extern void VP8SSIMDspInitSSE2(void);
static volatile VP8CPUInfo ssim_last_cpuinfo_used =
(VP8CPUInfo)&ssim_last_cpuinfo_used;
WEBP_TSAN_IGNORE_FUNCTION void VP8SSIMDspInit(void) {
if (ssim_last_cpuinfo_used == VP8GetCPUInfo) return;
VP8SSIMGetClipped = SSIMGetClipped_C;
VP8SSIMGet = SSIMGet_C;
VP8AccumulateSSE = AccumulateSSE;
if (VP8GetCPUInfo != NULL) {
#if defined(WEBP_USE_SSE2)
if (VP8GetCPUInfo(kSSE2)) {
VP8SSIMDspInitSSE2();
}
#endif
}
ssim_last_cpuinfo_used = VP8GetCPUInfo;
}
//------------------------------------------------------------------------------
// Initialization
// Speed-critical function pointers. We have to initialize them to the default
// implementations within VP8EncDspInit().
VP8CHisto VP8CollectHistogram;
VP8Idct VP8ITransform;
VP8Fdct VP8FTransform;
VP8Fdct VP8FTransform2;
VP8WHT VP8FTransformWHT;
VP8Intra4Preds VP8EncPredLuma4;
VP8IntraPreds VP8EncPredLuma16;
VP8IntraPreds VP8EncPredChroma8;
VP8Metric VP8SSE16x16;
VP8Metric VP8SSE8x8;
VP8Metric VP8SSE16x8;
VP8Metric VP8SSE4x4;
VP8WMetric VP8TDisto4x4;
VP8WMetric VP8TDisto16x16;
VP8MeanMetric VP8Mean16x4;
VP8QuantizeBlock VP8EncQuantizeBlock;
VP8Quantize2Blocks VP8EncQuantize2Blocks;
VP8QuantizeBlockWHT VP8EncQuantizeBlockWHT;
VP8BlockCopy VP8Copy4x4;
VP8BlockCopy VP8Copy16x8;
extern void VP8EncDspInitSSE2(void);
extern void VP8EncDspInitSSE41(void);
extern void VP8EncDspInitAVX2(void);
extern void VP8EncDspInitNEON(void);
extern void VP8EncDspInitMIPS32(void);
extern void VP8EncDspInitMIPSdspR2(void);
extern void VP8EncDspInitMSA(void);
static volatile VP8CPUInfo enc_last_cpuinfo_used =
(VP8CPUInfo)&enc_last_cpuinfo_used;
WEBP_TSAN_IGNORE_FUNCTION void VP8EncDspInit(void) {
if (enc_last_cpuinfo_used == VP8GetCPUInfo) return;
VP8DspInit(); // common inverse transforms
InitTables();
// default C implementations
VP8CollectHistogram = CollectHistogram;
VP8ITransform = ITransform;
VP8FTransform = FTransform;
VP8FTransform2 = FTransform2;
VP8FTransformWHT = FTransformWHT;
VP8EncPredLuma4 = Intra4Preds;
VP8EncPredLuma16 = Intra16Preds;
VP8EncPredChroma8 = IntraChromaPreds;
VP8SSE16x16 = SSE16x16;
VP8SSE8x8 = SSE8x8;
VP8SSE16x8 = SSE16x8;
VP8SSE4x4 = SSE4x4;
VP8TDisto4x4 = Disto4x4;
VP8TDisto16x16 = Disto16x16;
VP8Mean16x4 = Mean16x4;
VP8EncQuantizeBlock = QuantizeBlock;
VP8EncQuantize2Blocks = Quantize2Blocks;
VP8EncQuantizeBlockWHT = QuantizeBlock;
VP8Copy4x4 = Copy4x4;
VP8Copy16x8 = Copy16x8;
// If defined, use CPUInfo() to overwrite some pointers with faster versions.
if (VP8GetCPUInfo != NULL) {
#if defined(WEBP_USE_SSE2)
if (VP8GetCPUInfo(kSSE2)) {
VP8EncDspInitSSE2();
#if defined(WEBP_USE_SSE41)
if (VP8GetCPUInfo(kSSE4_1)) {
VP8EncDspInitSSE41();
}
#endif
}
#endif
#if defined(WEBP_USE_AVX2)
if (VP8GetCPUInfo(kAVX2)) {
VP8EncDspInitAVX2();
}
#endif
#if defined(WEBP_USE_NEON)
if (VP8GetCPUInfo(kNEON)) {
VP8EncDspInitNEON();
}
#endif
#if defined(WEBP_USE_MIPS32)
if (VP8GetCPUInfo(kMIPS32)) {
VP8EncDspInitMIPS32();
}
#endif
#if defined(WEBP_USE_MIPS_DSP_R2)
if (VP8GetCPUInfo(kMIPSdspR2)) {
VP8EncDspInitMIPSdspR2();
}
#endif
#if defined(WEBP_USE_MSA)
if (VP8GetCPUInfo(kMSA)) {
VP8EncDspInitMSA();
}
#endif
}
enc_last_cpuinfo_used = VP8GetCPUInfo;
}