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FFmpeg4/libavcodec/texturedspenc.c

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2023-07-02 12:20:28 +00:00
/*
* Texture block compression
* Copyright (C) 2015 Vittorio Giovara <vittorio.giovara@gmail.com>
* Based on public domain code by Fabian Giesen, Sean Barrett and Yann Collet.
*
* This file is part of FFmpeg
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
* The above copyright notice and this permission notice shall be included
* in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*/
#include <stddef.h>
#include <stdint.h>
#include "libavutil/attributes.h"
#include "libavutil/common.h"
#include "libavutil/intreadwrite.h"
#include "texturedsp.h"
static const uint8_t expand5[32] = {
0, 8, 16, 24, 33, 41, 49, 57, 66, 74, 82, 90,
99, 107, 115, 123, 132, 140, 148, 156, 165, 173, 181, 189,
198, 206, 214, 222, 231, 239, 247, 255,
};
static const uint8_t expand6[64] = {
0, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44,
48, 52, 56, 60, 65, 69, 73, 77, 81, 85, 89, 93,
97, 101, 105, 109, 113, 117, 121, 125, 130, 134, 138, 142,
146, 150, 154, 158, 162, 166, 170, 174, 178, 182, 186, 190,
195, 199, 203, 207, 211, 215, 219, 223, 227, 231, 235, 239,
243, 247, 251, 255,
};
static const uint8_t match5[256][2] = {
{ 0, 0 }, { 0, 0 }, { 0, 1 }, { 0, 1 }, { 1, 0 }, { 1, 0 },
{ 1, 0 }, { 1, 1 }, { 1, 1 }, { 2, 0 }, { 2, 0 }, { 0, 4 },
{ 2, 1 }, { 2, 1 }, { 2, 1 }, { 3, 0 }, { 3, 0 }, { 3, 0 },
{ 3, 1 }, { 1, 5 }, { 3, 2 }, { 3, 2 }, { 4, 0 }, { 4, 0 },
{ 4, 1 }, { 4, 1 }, { 4, 2 }, { 4, 2 }, { 4, 2 }, { 3, 5 },
{ 5, 1 }, { 5, 1 }, { 5, 2 }, { 4, 4 }, { 5, 3 }, { 5, 3 },
{ 5, 3 }, { 6, 2 }, { 6, 2 }, { 6, 2 }, { 6, 3 }, { 5, 5 },
{ 6, 4 }, { 6, 4 }, { 4, 8 }, { 7, 3 }, { 7, 3 }, { 7, 3 },
{ 7, 4 }, { 7, 4 }, { 7, 4 }, { 7, 5 }, { 5, 9 }, { 7, 6 },
{ 7, 6 }, { 8, 4 }, { 8, 4 }, { 8, 5 }, { 8, 5 }, { 8, 6 },
{ 8, 6 }, { 8, 6 }, { 7, 9 }, { 9, 5 }, { 9, 5 }, { 9, 6 },
{ 8, 8 }, { 9, 7 }, { 9, 7 }, { 9, 7 }, { 10, 6 }, { 10, 6 },
{ 10, 6 }, { 10, 7 }, { 9, 9 }, { 10, 8 }, { 10, 8 }, { 8, 12 },
{ 11, 7 }, { 11, 7 }, { 11, 7 }, { 11, 8 }, { 11, 8 }, { 11, 8 },
{ 11, 9 }, { 9, 13 }, { 11, 10 }, { 11, 10 }, { 12, 8 }, { 12, 8 },
{ 12, 9 }, { 12, 9 }, { 12, 10 }, { 12, 10 }, { 12, 10 }, { 11, 13 },
{ 13, 9 }, { 13, 9 }, { 13, 10 }, { 12, 12 }, { 13, 11 }, { 13, 11 },
{ 13, 11 }, { 14, 10 }, { 14, 10 }, { 14, 10 }, { 14, 11 }, { 13, 13 },
{ 14, 12 }, { 14, 12 }, { 12, 16 }, { 15, 11 }, { 15, 11 }, { 15, 11 },
{ 15, 12 }, { 15, 12 }, { 15, 12 }, { 15, 13 }, { 13, 17 }, { 15, 14 },
{ 15, 14 }, { 16, 12 }, { 16, 12 }, { 16, 13 }, { 16, 13 }, { 16, 14 },
{ 16, 14 }, { 16, 14 }, { 15, 17 }, { 17, 13 }, { 17, 13 }, { 17, 14 },
{ 16, 16 }, { 17, 15 }, { 17, 15 }, { 17, 15 }, { 18, 14 }, { 18, 14 },
{ 18, 14 }, { 18, 15 }, { 17, 17 }, { 18, 16 }, { 18, 16 }, { 16, 20 },
{ 19, 15 }, { 19, 15 }, { 19, 15 }, { 19, 16 }, { 19, 16 }, { 19, 16 },
{ 19, 17 }, { 17, 21 }, { 19, 18 }, { 19, 18 }, { 20, 16 }, { 20, 16 },
{ 20, 17 }, { 20, 17 }, { 20, 18 }, { 20, 18 }, { 20, 18 }, { 19, 21 },
{ 21, 17 }, { 21, 17 }, { 21, 18 }, { 20, 20 }, { 21, 19 }, { 21, 19 },
{ 21, 19 }, { 22, 18 }, { 22, 18 }, { 22, 18 }, { 22, 19 }, { 21, 21 },
{ 22, 20 }, { 22, 20 }, { 20, 24 }, { 23, 19 }, { 23, 19 }, { 23, 19 },
{ 23, 20 }, { 23, 20 }, { 23, 20 }, { 23, 21 }, { 21, 25 }, { 23, 22 },
{ 23, 22 }, { 24, 20 }, { 24, 20 }, { 24, 21 }, { 24, 21 }, { 24, 22 },
{ 24, 22 }, { 24, 22 }, { 23, 25 }, { 25, 21 }, { 25, 21 }, { 25, 22 },
{ 24, 24 }, { 25, 23 }, { 25, 23 }, { 25, 23 }, { 26, 22 }, { 26, 22 },
{ 26, 22 }, { 26, 23 }, { 25, 25 }, { 26, 24 }, { 26, 24 }, { 24, 28 },
{ 27, 23 }, { 27, 23 }, { 27, 23 }, { 27, 24 }, { 27, 24 }, { 27, 24 },
{ 27, 25 }, { 25, 29 }, { 27, 26 }, { 27, 26 }, { 28, 24 }, { 28, 24 },
{ 28, 25 }, { 28, 25 }, { 28, 26 }, { 28, 26 }, { 28, 26 }, { 27, 29 },
{ 29, 25 }, { 29, 25 }, { 29, 26 }, { 28, 28 }, { 29, 27 }, { 29, 27 },
{ 29, 27 }, { 30, 26 }, { 30, 26 }, { 30, 26 }, { 30, 27 }, { 29, 29 },
{ 30, 28 }, { 30, 28 }, { 30, 28 }, { 31, 27 }, { 31, 27 }, { 31, 27 },
{ 31, 28 }, { 31, 28 }, { 31, 28 }, { 31, 29 }, { 31, 29 }, { 31, 30 },
{ 31, 30 }, { 31, 30 }, { 31, 31 }, { 31, 31 },
};
static const uint8_t match6[256][2] = {
{ 0, 0 }, { 0, 1 }, { 1, 0 }, { 1, 0 }, { 1, 1 }, { 2, 0 },
{ 2, 1 }, { 3, 0 }, { 3, 0 }, { 3, 1 }, { 4, 0 }, { 4, 0 },
{ 4, 1 }, { 5, 0 }, { 5, 1 }, { 6, 0 }, { 6, 0 }, { 6, 1 },
{ 7, 0 }, { 7, 0 }, { 7, 1 }, { 8, 0 }, { 8, 1 }, { 8, 1 },
{ 8, 2 }, { 9, 1 }, { 9, 2 }, { 9, 2 }, { 9, 3 }, { 10, 2 },
{ 10, 3 }, { 10, 3 }, { 10, 4 }, { 11, 3 }, { 11, 4 }, { 11, 4 },
{ 11, 5 }, { 12, 4 }, { 12, 5 }, { 12, 5 }, { 12, 6 }, { 13, 5 },
{ 13, 6 }, { 8, 16 }, { 13, 7 }, { 14, 6 }, { 14, 7 }, { 9, 17 },
{ 14, 8 }, { 15, 7 }, { 15, 8 }, { 11, 16 }, { 15, 9 }, { 15, 10 },
{ 16, 8 }, { 16, 9 }, { 16, 10 }, { 15, 13 }, { 17, 9 }, { 17, 10 },
{ 17, 11 }, { 15, 16 }, { 18, 10 }, { 18, 11 }, { 18, 12 }, { 16, 16 },
{ 19, 11 }, { 19, 12 }, { 19, 13 }, { 17, 17 }, { 20, 12 }, { 20, 13 },
{ 20, 14 }, { 19, 16 }, { 21, 13 }, { 21, 14 }, { 21, 15 }, { 20, 17 },
{ 22, 14 }, { 22, 15 }, { 25, 10 }, { 22, 16 }, { 23, 15 }, { 23, 16 },
{ 26, 11 }, { 23, 17 }, { 24, 16 }, { 24, 17 }, { 27, 12 }, { 24, 18 },
{ 25, 17 }, { 25, 18 }, { 28, 13 }, { 25, 19 }, { 26, 18 }, { 26, 19 },
{ 29, 14 }, { 26, 20 }, { 27, 19 }, { 27, 20 }, { 30, 15 }, { 27, 21 },
{ 28, 20 }, { 28, 21 }, { 28, 21 }, { 28, 22 }, { 29, 21 }, { 29, 22 },
{ 24, 32 }, { 29, 23 }, { 30, 22 }, { 30, 23 }, { 25, 33 }, { 30, 24 },
{ 31, 23 }, { 31, 24 }, { 27, 32 }, { 31, 25 }, { 31, 26 }, { 32, 24 },
{ 32, 25 }, { 32, 26 }, { 31, 29 }, { 33, 25 }, { 33, 26 }, { 33, 27 },
{ 31, 32 }, { 34, 26 }, { 34, 27 }, { 34, 28 }, { 32, 32 }, { 35, 27 },
{ 35, 28 }, { 35, 29 }, { 33, 33 }, { 36, 28 }, { 36, 29 }, { 36, 30 },
{ 35, 32 }, { 37, 29 }, { 37, 30 }, { 37, 31 }, { 36, 33 }, { 38, 30 },
{ 38, 31 }, { 41, 26 }, { 38, 32 }, { 39, 31 }, { 39, 32 }, { 42, 27 },
{ 39, 33 }, { 40, 32 }, { 40, 33 }, { 43, 28 }, { 40, 34 }, { 41, 33 },
{ 41, 34 }, { 44, 29 }, { 41, 35 }, { 42, 34 }, { 42, 35 }, { 45, 30 },
{ 42, 36 }, { 43, 35 }, { 43, 36 }, { 46, 31 }, { 43, 37 }, { 44, 36 },
{ 44, 37 }, { 44, 37 }, { 44, 38 }, { 45, 37 }, { 45, 38 }, { 40, 48 },
{ 45, 39 }, { 46, 38 }, { 46, 39 }, { 41, 49 }, { 46, 40 }, { 47, 39 },
{ 47, 40 }, { 43, 48 }, { 47, 41 }, { 47, 42 }, { 48, 40 }, { 48, 41 },
{ 48, 42 }, { 47, 45 }, { 49, 41 }, { 49, 42 }, { 49, 43 }, { 47, 48 },
{ 50, 42 }, { 50, 43 }, { 50, 44 }, { 48, 48 }, { 51, 43 }, { 51, 44 },
{ 51, 45 }, { 49, 49 }, { 52, 44 }, { 52, 45 }, { 52, 46 }, { 51, 48 },
{ 53, 45 }, { 53, 46 }, { 53, 47 }, { 52, 49 }, { 54, 46 }, { 54, 47 },
{ 57, 42 }, { 54, 48 }, { 55, 47 }, { 55, 48 }, { 58, 43 }, { 55, 49 },
{ 56, 48 }, { 56, 49 }, { 59, 44 }, { 56, 50 }, { 57, 49 }, { 57, 50 },
{ 60, 45 }, { 57, 51 }, { 58, 50 }, { 58, 51 }, { 61, 46 }, { 58, 52 },
{ 59, 51 }, { 59, 52 }, { 62, 47 }, { 59, 53 }, { 60, 52 }, { 60, 53 },
{ 60, 53 }, { 60, 54 }, { 61, 53 }, { 61, 54 }, { 61, 54 }, { 61, 55 },
{ 62, 54 }, { 62, 55 }, { 62, 55 }, { 62, 56 }, { 63, 55 }, { 63, 56 },
{ 63, 56 }, { 63, 57 }, { 63, 58 }, { 63, 59 }, { 63, 59 }, { 63, 60 },
{ 63, 61 }, { 63, 62 }, { 63, 62 }, { 63, 63 },
};
/* Multiplication over 8 bit emulation */
#define mul8(a, b) (((a) * (b) + 128 + (((a) * (b) + 128) >> 8)) >> 8)
/* Conversion from rgb24 to rgb565 */
#define rgb2rgb565(r, g, b) \
((mul8(r, 31) << 11) | (mul8(g, 63) << 5) | (mul8(b, 31) << 0))
/* Linear interpolation at 1/3 point between a and b */
#define lerp13(a, b) ((2 * (a) + (b)) / 3)
/* Linear interpolation on an RGB pixel */
static inline void lerp13rgb(uint8_t *out, uint8_t *p1, uint8_t *p2)
{
out[0] = lerp13(p1[0], p2[0]);
out[1] = lerp13(p1[1], p2[1]);
out[2] = lerp13(p1[2], p2[2]);
}
/* Conversion from rgb565 to rgb24 */
static inline void rgb5652rgb(uint8_t *out, uint16_t v)
{
int rv = (v & 0xf800) >> 11;
int gv = (v & 0x07e0) >> 5;
int bv = (v & 0x001f) >> 0;
out[0] = expand5[rv];
out[1] = expand6[gv];
out[2] = expand5[bv];
out[3] = 0;
}
/* Color matching function */
static unsigned int match_colors(const uint8_t *block, ptrdiff_t stride,
uint16_t c0, uint16_t c1)
{
uint32_t mask = 0;
int dirr, dirg, dirb;
int dots[16];
int stops[4];
int x, y, k = 0;
int c0_point, half_point, c3_point;
uint8_t color[16];
static const int indexMap[8] = {
0 << 30, 2 << 30, 0 << 30, 2 << 30,
3 << 30, 3 << 30, 1 << 30, 1 << 30,
};
/* Fill color and compute direction for each component */
rgb5652rgb(color + 0, c0);
rgb5652rgb(color + 4, c1);
lerp13rgb(color + 8, color + 0, color + 4);
lerp13rgb(color + 12, color + 4, color + 0);
dirr = color[0 * 4 + 0] - color[1 * 4 + 0];
dirg = color[0 * 4 + 1] - color[1 * 4 + 1];
dirb = color[0 * 4 + 2] - color[1 * 4 + 2];
for (y = 0; y < 4; y++) {
for (x = 0; x < 4; x++)
dots[k++] = block[0 + x * 4 + y * stride] * dirr +
block[1 + x * 4 + y * stride] * dirg +
block[2 + x * 4 + y * stride] * dirb;
stops[y] = color[0 + y * 4] * dirr +
color[1 + y * 4] * dirg +
color[2 + y * 4] * dirb;
}
/* Think of the colors as arranged on a line; project point onto that line,
* then choose next color out of available ones. we compute the crossover
* points for 'best color in top half'/'best in bottom half' and then
* the same inside that subinterval.
*
* Relying on this 1d approximation isn't always optimal in terms of
* Euclidean distance, but it's very close and a lot faster.
*
* http://cbloomrants.blogspot.com/2008/12/12-08-08-dxtc-summary.html */
c0_point = (stops[1] + stops[3]) >> 1;
half_point = (stops[3] + stops[2]) >> 1;
c3_point = (stops[2] + stops[0]) >> 1;
for (x = 0; x < 16; x++) {
int dot = dots[x];
int bits = (dot < half_point ? 4 : 0) |
(dot < c0_point ? 2 : 0) |
(dot < c3_point ? 1 : 0);
mask >>= 2;
mask |= indexMap[bits];
}
return mask;
}
/* Color optimization function */
static void optimize_colors(const uint8_t *block, ptrdiff_t stride,
uint16_t *pmax16, uint16_t *pmin16)
{
const uint8_t *minp;
const uint8_t *maxp;
const int iter_power = 4;
double magn;
int v_r, v_g, v_b;
float covf[6], vfr, vfg, vfb;
int mind, maxd;
int cov[6] = { 0 };
int mu[3], min[3], max[3];
int ch, iter, x, y;
/* Determine color distribution */
for (ch = 0; ch < 3; ch++) {
const uint8_t *bp = &block[ch];
int muv, minv, maxv;
muv = minv = maxv = bp[0];
for (y = 0; y < 4; y++) {
for (x = 0; x < 4; x++) {
muv += bp[x * 4 + y * stride];
if (bp[x * 4 + y * stride] < minv)
minv = bp[x * 4 + y * stride];
else if (bp[x * 4 + y * stride] > maxv)
maxv = bp[x * 4 + y * stride];
}
}
mu[ch] = (muv + 8) >> 4;
min[ch] = minv;
max[ch] = maxv;
}
/* Determine covariance matrix */
for (y = 0; y < 4; y++) {
for (x = 0; x < 4; x++) {
int r = block[x * 4 + stride * y + 0] - mu[0];
int g = block[x * 4 + stride * y + 1] - mu[1];
int b = block[x * 4 + stride * y + 2] - mu[2];
cov[0] += r * r;
cov[1] += r * g;
cov[2] += r * b;
cov[3] += g * g;
cov[4] += g * b;
cov[5] += b * b;
}
}
/* Convert covariance matrix to float, find principal axis via power iter */
for (x = 0; x < 6; x++)
covf[x] = cov[x] / 255.0f;
vfr = (float) (max[0] - min[0]);
vfg = (float) (max[1] - min[1]);
vfb = (float) (max[2] - min[2]);
for (iter = 0; iter < iter_power; iter++) {
float r = vfr * covf[0] + vfg * covf[1] + vfb * covf[2];
float g = vfr * covf[1] + vfg * covf[3] + vfb * covf[4];
float b = vfr * covf[2] + vfg * covf[4] + vfb * covf[5];
vfr = r;
vfg = g;
vfb = b;
}
magn = fabs(vfr);
if (fabs(vfg) > magn)
magn = fabs(vfg);
if (fabs(vfb) > magn)
magn = fabs(vfb);
/* if magnitude is too small, default to luminance */
if (magn < 4.0f) {
/* JPEG YCbCr luma coefs, scaled by 1000 */
v_r = 299;
v_g = 587;
v_b = 114;
} else {
magn = 512.0 / magn;
v_r = (int) (vfr * magn);
v_g = (int) (vfg * magn);
v_b = (int) (vfb * magn);
}
/* Pick colors at extreme points */
mind = maxd = block[0] * v_r + block[1] * v_g + block[2] * v_b;
minp = maxp = block;
for (y = 0; y < 4; y++) {
for (x = 0; x < 4; x++) {
int dot = block[x * 4 + y * stride + 0] * v_r +
block[x * 4 + y * stride + 1] * v_g +
block[x * 4 + y * stride + 2] * v_b;
if (dot < mind) {
mind = dot;
minp = block + x * 4 + y * stride;
} else if (dot > maxd) {
maxd = dot;
maxp = block + x * 4 + y * stride;
}
}
}
*pmax16 = rgb2rgb565(maxp[0], maxp[1], maxp[2]);
*pmin16 = rgb2rgb565(minp[0], minp[1], minp[2]);
}
/* Try to optimize colors to suit block contents better, by solving
* a least squares system via normal equations + Cramer's rule. */
static int refine_colors(const uint8_t *block, ptrdiff_t stride,
uint16_t *pmax16, uint16_t *pmin16, uint32_t mask)
{
uint32_t cm = mask;
uint16_t oldMin = *pmin16;
uint16_t oldMax = *pmax16;
uint16_t min16, max16;
int x, y;
/* Additional magic to save a lot of multiplies in the accumulating loop.
* The tables contain precomputed products of weights for least squares
* system, accumulated inside one 32-bit register */
static const int w1tab[4] = { 3, 0, 2, 1 };
static const int prods[4] = { 0x090000, 0x000900, 0x040102, 0x010402 };
/* Check if all pixels have the same index */
if ((mask ^ (mask << 2)) < 4) {
/* If so, linear system would be singular; solve using optimal
* single-color match on average color. */
int r = 8, g = 8, b = 8;
for (y = 0; y < 4; y++) {
for (x = 0; x < 4; x++) {
r += block[0 + x * 4 + y * stride];
g += block[1 + x * 4 + y * stride];
b += block[2 + x * 4 + y * stride];
}
}
r >>= 4;
g >>= 4;
b >>= 4;
max16 = (match5[r][0] << 11) | (match6[g][0] << 5) | match5[b][0];
min16 = (match5[r][1] << 11) | (match6[g][1] << 5) | match5[b][1];
} else {
float fr, fg, fb;
int at1_r = 0, at1_g = 0, at1_b = 0;
int at2_r = 0, at2_g = 0, at2_b = 0;
int akku = 0;
int xx, xy, yy;
for (y = 0; y < 4; y++) {
for (x = 0; x < 4; x++) {
int step = cm & 3;
int w1 = w1tab[step];
int r = block[0 + x * 4 + y * stride];
int g = block[1 + x * 4 + y * stride];
int b = block[2 + x * 4 + y * stride];
akku += prods[step];
at1_r += w1 * r;
at1_g += w1 * g;
at1_b += w1 * b;
at2_r += r;
at2_g += g;
at2_b += b;
cm >>= 2;
}
}
at2_r = 3 * at2_r - at1_r;
at2_g = 3 * at2_g - at1_g;
at2_b = 3 * at2_b - at1_b;
/* Extract solutions and decide solvability */
xx = akku >> 16;
yy = (akku >> 8) & 0xFF;
xy = (akku >> 0) & 0xFF;
fr = 3.0f * 31.0f / 255.0f / (xx * yy - xy * xy);
fg = fr * 63.0f / 31.0f;
fb = fr;
/* Solve */
max16 = av_clip_uintp2((at1_r * yy - at2_r * xy) * fr + 0.5f, 5) << 11;
max16 |= av_clip_uintp2((at1_g * yy - at2_g * xy) * fg + 0.5f, 6) << 5;
max16 |= av_clip_uintp2((at1_b * yy - at2_b * xy) * fb + 0.5f, 5) << 0;
min16 = av_clip_uintp2((at2_r * xx - at1_r * xy) * fr + 0.5f, 5) << 11;
min16 |= av_clip_uintp2((at2_g * xx - at1_g * xy) * fg + 0.5f, 6) << 5;
min16 |= av_clip_uintp2((at2_b * xx - at1_b * xy) * fb + 0.5f, 5) << 0;
}
*pmin16 = min16;
*pmax16 = max16;
return oldMin != min16 || oldMax != max16;
}
/* Check if input block is a constant color */
static int constant_color(const uint8_t *block, ptrdiff_t stride)
{
int x, y;
uint32_t first = AV_RL32(block);
for (y = 0; y < 4; y++)
for (x = 0; x < 4; x++)
if (first != AV_RL32(block + x * 4 + y * stride))
return 0;
return 1;
}
/* Main color compression function */
static void compress_color(uint8_t *dst, ptrdiff_t stride, const uint8_t *block)
{
uint32_t mask;
uint16_t max16, min16;
int constant = constant_color(block, stride);
/* Constant color will load values from tables */
if (constant) {
int r = block[0];
int g = block[1];
int b = block[2];
mask = 0xAAAAAAAA;
max16 = (match5[r][0] << 11) | (match6[g][0] << 5) | match5[b][0];
min16 = (match5[r][1] << 11) | (match6[g][1] << 5) | match5[b][1];
} else {
int refine;
/* Otherwise find pca and map along principal axis */
optimize_colors(block, stride, &max16, &min16);
if (max16 != min16)
mask = match_colors(block, stride, max16, min16);
else
mask = 0;
/* One pass refinement */
refine = refine_colors(block, stride, &max16, &min16, mask);
if (refine) {
if (max16 != min16)
mask = match_colors(block, stride, max16, min16);
else
mask = 0;
}
}
/* Finally write the color block */
if (max16 < min16) {
FFSWAP(uint16_t, min16, max16);
mask ^= 0x55555555;
}
AV_WL16(dst + 0, max16);
AV_WL16(dst + 2, min16);
AV_WL32(dst + 4, mask);
}
/* Alpha compression function */
static void compress_alpha(uint8_t *dst, ptrdiff_t stride, const uint8_t *block)
{
int x, y;
int dist, bias, dist4, dist2;
int mn, mx;
int bits = 0;
int mask = 0;
memset(dst, 0, 8);
/* Find min/max color */
mn = mx = block[3];
for (y = 0; y < 4; y++) {
for (x = 0; x < 4; x++) {
int val = block[3 + x * 4 + y * stride];
if (val < mn)
mn = val;
else if (val > mx)
mx = val;
}
}
/* Encode them */
dst[0] = (uint8_t) mx;
dst[1] = (uint8_t) mn;
dst += 2;
/* Mono-alpha shortcut */
if (mn == mx)
return;
/* Determine bias and emit color indices.
* Given the choice of mx/mn, these indices are optimal:
* fgiesen.wordpress.com/2009/12/15/dxt5-alpha-block-index-determination */
dist = mx - mn;
dist4 = dist * 4;
dist2 = dist * 2;
if (dist < 8)
bias = dist - 1 - mn * 7;
else
bias = dist / 2 + 2 - mn * 7;
for (y = 0; y < 4; y++) {
for (x = 0; x < 4; x++) {
int alp = block[3 + x * 4 + y * stride] * 7 + bias;
int ind, tmp;
/* This is a "linear scale" lerp factor between 0 (val=min)
* and 7 (val=max) to select index. */
tmp = (alp >= dist4) ? -1 : 0;
ind = tmp & 4;
alp -= dist4 & tmp;
tmp = (alp >= dist2) ? -1 : 0;
ind += tmp & 2;
alp -= dist2 & tmp;
ind += (alp >= dist);
/* Turn linear scale into DXT index (0/1 are extreme points) */
ind = -ind & 7;
ind ^= (2 > ind);
/* Write index */
mask |= ind << bits;
bits += 3;
if (bits >= 8) {
*dst++ = mask;
mask >>= 8;
bits -= 8;
}
}
}
}
/**
* Convert a RGBA buffer to unscaled YCoCg.
* Scale is usually introduced to avoid banding over a certain range of colors,
* but this version of the algorithm does not introduce it as much as other
* implementations, allowing for a simpler and faster conversion.
*/
static void rgba2ycocg(uint8_t *dst, const uint8_t *pixel)
{
int r = pixel[0];
int g = (pixel[1] + 1) >> 1;
int b = pixel[2];
int t = (2 + r + b) >> 2;
dst[0] = av_clip_uint8(128 + ((r - b + 1) >> 1)); /* Co */
dst[1] = av_clip_uint8(128 + g - t); /* Cg */
dst[2] = 0;
dst[3] = av_clip_uint8(g + t); /* Y */
}
/**
* Compress one block of RGBA pixels in a DXT1 texture and store the
* resulting bytes in 'dst'. Alpha is not preserved.
*
* @param dst output buffer.
* @param stride scanline in bytes.
* @param block block to compress.
* @return how much texture data has been written.
*/
static int dxt1_block(uint8_t *dst, ptrdiff_t stride, const uint8_t *block)
{
compress_color(dst, stride, block);
return 8;
}
/**
* Compress one block of RGBA pixels in a DXT5 texture and store the
* resulting bytes in 'dst'. Alpha is preserved.
*
* @param dst output buffer.
* @param stride scanline in bytes.
* @param block block to compress.
* @return how much texture data has been written.
*/
static int dxt5_block(uint8_t *dst, ptrdiff_t stride, const uint8_t *block)
{
compress_alpha(dst, stride, block);
compress_color(dst + 8, stride, block);
return 16;
}
/**
* Compress one block of RGBA pixels in a DXT5-YCoCg texture and store the
* resulting bytes in 'dst'. Alpha is not preserved.
*
* @param dst output buffer.
* @param stride scanline in bytes.
* @param block block to compress.
* @return how much texture data has been written.
*/
static int dxt5ys_block(uint8_t *dst, ptrdiff_t stride, const uint8_t *block)
{
int x, y;
uint8_t reorder[64];
/* Reorder the components and then run a normal DXT5 compression. */
for (y = 0; y < 4; y++)
for (x = 0; x < 4; x++)
rgba2ycocg(reorder + x * 4 + y * 16, block + x * 4 + y * stride);
compress_alpha(dst + 0, 16, reorder);
compress_color(dst + 8, 16, reorder);
return 16;
}
/**
* Compress one block of RGBA pixels in a RGTC1U texture and store the
* resulting bytes in 'dst'. Use the alpha channel of the input image.
*
* @param dst output buffer.
* @param stride scanline in bytes.
* @param block block to compress.
* @return how much texture data has been written.
*/
static int rgtc1u_alpha_block(uint8_t *dst, ptrdiff_t stride, const uint8_t *block)
{
compress_alpha(dst, stride, block);
return 8;
}
av_cold void ff_texturedspenc_init(TextureDSPContext *c)
{
c->dxt1_block = dxt1_block;
c->dxt5_block = dxt5_block;
c->dxt5ys_block = dxt5ys_block;
c->rgtc1u_alpha_block = rgtc1u_alpha_block;
}