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d20b7707137f3848930a8f851bebdbda2af0f2c0
libwebp/src/enc/picture_csp_enc.c
James Zern 0d5fad46cf add WEBP_DSP_INIT / WEBP_DSP_INIT_FUNC 
this internalizes the init checks and provides stronger synchronization
with pthreads when available while still allowing VP8GetCPUInfo to be
modified (mostly for testing purposes). windows is left as is since a
critical section or mutex would cause a leak.

Change-Id: Ieb997e014f2805c0ae39c16f13337663521356f4
(cherry picked from commit d77bf512bd)
2018-04-17 18:01:34 -07:00

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// Copyright 2014 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.
// -----------------------------------------------------------------------------
//
// WebPPicture utils for colorspace conversion
//
// Author: Skal (pascal.massimino@gmail.com)
#include <assert.h>
#include <stdlib.h>
#include <math.h>
#include "src/enc/vp8i_enc.h"
#include "src/utils/random_utils.h"
#include "src/utils/utils.h"
#include "src/dsp/dsp.h"
#include "src/dsp/lossless.h"
#include "src/dsp/yuv.h"
// Uncomment to disable gamma-compression during RGB->U/V averaging
#define USE_GAMMA_COMPRESSION
// If defined, use table to compute x / alpha.
#define USE_INVERSE_ALPHA_TABLE
#ifdef WORDS_BIGENDIAN
#define ALPHA_OFFSET 0 // uint32_t 0xff000000 is 0xff,00,00,00 in memory
#else
#define ALPHA_OFFSET 3 // uint32_t 0xff000000 is 0x00,00,00,ff in memory
#endif
//------------------------------------------------------------------------------
// Detection of non-trivial transparency
// Returns true if alpha[] has non-0xff values.
static int CheckNonOpaque(const uint8_t* alpha, int width, int height,
int x_step, int y_step) {
if (alpha == NULL) return 0;
WebPInitAlphaProcessing();
if (x_step == 1) {
for (; height-- > 0; alpha += y_step) {
if (WebPHasAlpha8b(alpha, width)) return 1;
}
} else {
for (; height-- > 0; alpha += y_step) {
if (WebPHasAlpha32b(alpha, width)) return 1;
}
}
return 0;
}
// Checking for the presence of non-opaque alpha.
int WebPPictureHasTransparency(const WebPPicture* picture) {
if (picture == NULL) return 0;
if (!picture->use_argb) {
return CheckNonOpaque(picture->a, picture->width, picture->height,
1, picture->a_stride);
} else {
const int alpha_offset = ALPHA_OFFSET;
return CheckNonOpaque((const uint8_t*)picture->argb + alpha_offset,
picture->width, picture->height,
4, picture->argb_stride * sizeof(*picture->argb));
}
return 0;
}
//------------------------------------------------------------------------------
// Code for gamma correction
#if defined(USE_GAMMA_COMPRESSION)
// gamma-compensates loss of resolution during chroma subsampling
#define kGamma 0.80 // for now we use a different gamma value than kGammaF
#define kGammaFix 12 // fixed-point precision for linear values
#define kGammaScale ((1 << kGammaFix) - 1)
#define kGammaTabFix 7 // fixed-point fractional bits precision
#define kGammaTabScale (1 << kGammaTabFix)
#define kGammaTabRounder (kGammaTabScale >> 1)
#define kGammaTabSize (1 << (kGammaFix - kGammaTabFix))
static int kLinearToGammaTab[kGammaTabSize + 1];
static uint16_t kGammaToLinearTab[256];
static volatile int kGammaTablesOk = 0;
static WEBP_TSAN_IGNORE_FUNCTION void InitGammaTables(void) {
if (!kGammaTablesOk) {
int v;
const double scale = (double)(1 << kGammaTabFix) / kGammaScale;
const double norm = 1. / 255.;
for (v = 0; v <= 255; ++v) {
kGammaToLinearTab[v] =
(uint16_t)(pow(norm * v, kGamma) * kGammaScale + .5);
}
for (v = 0; v <= kGammaTabSize; ++v) {
kLinearToGammaTab[v] = (int)(255. * pow(scale * v, 1. / kGamma) + .5);
}
kGammaTablesOk = 1;
}
}
static WEBP_INLINE uint32_t GammaToLinear(uint8_t v) {
return kGammaToLinearTab[v];
}
static WEBP_INLINE int Interpolate(int v) {
const int tab_pos = v >> (kGammaTabFix + 2); // integer part
const int x = v & ((kGammaTabScale << 2) - 1); // fractional part
const int v0 = kLinearToGammaTab[tab_pos];
const int v1 = kLinearToGammaTab[tab_pos + 1];
const int y = v1 * x + v0 * ((kGammaTabScale << 2) - x); // interpolate
assert(tab_pos + 1 < kGammaTabSize + 1);
return y;
}
// Convert a linear value 'v' to YUV_FIX+2 fixed-point precision
// U/V value, suitable for RGBToU/V calls.
static WEBP_INLINE int LinearToGamma(uint32_t base_value, int shift) {
const int y = Interpolate(base_value << shift); // final uplifted value
return (y + kGammaTabRounder) >> kGammaTabFix; // descale
}
#else
static void InitGammaTables(void) {}
static WEBP_INLINE uint32_t GammaToLinear(uint8_t v) { return v; }
static WEBP_INLINE int LinearToGamma(uint32_t base_value, int shift) {
return (int)(base_value << shift);
}
#endif // USE_GAMMA_COMPRESSION
//------------------------------------------------------------------------------
// RGB -> YUV conversion
static int RGBToY(int r, int g, int b, VP8Random* const rg) {
return (rg == NULL) ? VP8RGBToY(r, g, b, YUV_HALF)
: VP8RGBToY(r, g, b, VP8RandomBits(rg, YUV_FIX));
}
static int RGBToU(int r, int g, int b, VP8Random* const rg) {
return (rg == NULL) ? VP8RGBToU(r, g, b, YUV_HALF << 2)
: VP8RGBToU(r, g, b, VP8RandomBits(rg, YUV_FIX + 2));
}
static int RGBToV(int r, int g, int b, VP8Random* const rg) {
return (rg == NULL) ? VP8RGBToV(r, g, b, YUV_HALF << 2)
: VP8RGBToV(r, g, b, VP8RandomBits(rg, YUV_FIX + 2));
}
//------------------------------------------------------------------------------
// Sharp RGB->YUV conversion
static const int kNumIterations = 4;
static const int kMinDimensionIterativeConversion = 4;
// We could use SFIX=0 and only uint8_t for fixed_y_t, but it produces some
// banding sometimes. Better use extra precision.
#define SFIX 2 // fixed-point precision of RGB and Y/W
typedef int16_t fixed_t; // signed type with extra SFIX precision for UV
typedef uint16_t fixed_y_t; // unsigned type with extra SFIX precision for W
#define SHALF (1 << SFIX >> 1)
#define MAX_Y_T ((256 << SFIX) - 1)
#define SROUNDER (1 << (YUV_FIX + SFIX - 1))
#if defined(USE_GAMMA_COMPRESSION)
// We use tables of different size and precision for the Rec709 / BT2020
// transfer function.
#define kGammaF (1./0.45)
static uint32_t kLinearToGammaTabS[kGammaTabSize + 2];
#define GAMMA_TO_LINEAR_BITS 14
static uint32_t kGammaToLinearTabS[MAX_Y_T + 1]; // size scales with Y_FIX
static volatile int kGammaTablesSOk = 0;
static WEBP_TSAN_IGNORE_FUNCTION void InitGammaTablesS(void) {
assert(2 * GAMMA_TO_LINEAR_BITS < 32); // we use uint32_t intermediate values
if (!kGammaTablesSOk) {
int v;
const double norm = 1. / MAX_Y_T;
const double scale = 1. / kGammaTabSize;
const double a = 0.09929682680944;
const double thresh = 0.018053968510807;
const double final_scale = 1 << GAMMA_TO_LINEAR_BITS;
for (v = 0; v <= MAX_Y_T; ++v) {
const double g = norm * v;
double value;
if (g <= thresh * 4.5) {
value = g / 4.5;
} else {
const double a_rec = 1. / (1. + a);
value = pow(a_rec * (g + a), kGammaF);
}
kGammaToLinearTabS[v] = (uint32_t)(value * final_scale + .5);
}
for (v = 0; v <= kGammaTabSize; ++v) {
const double g = scale * v;
double value;
if (g <= thresh) {
value = 4.5 * g;
} else {
value = (1. + a) * pow(g, 1. / kGammaF) - a;
}
// we already incorporate the 1/2 rounding constant here
kLinearToGammaTabS[v] =
(uint32_t)(MAX_Y_T * value) + (1 << GAMMA_TO_LINEAR_BITS >> 1);
}
// to prevent small rounding errors to cause read-overflow:
kLinearToGammaTabS[kGammaTabSize + 1] = kLinearToGammaTabS[kGammaTabSize];
kGammaTablesSOk = 1;
}
}
// return value has a fixed-point precision of GAMMA_TO_LINEAR_BITS
static WEBP_INLINE uint32_t GammaToLinearS(int v) {
return kGammaToLinearTabS[v];
}
static WEBP_INLINE uint32_t LinearToGammaS(uint32_t value) {
// 'value' is in GAMMA_TO_LINEAR_BITS fractional precision
const uint32_t v = value * kGammaTabSize;
const uint32_t tab_pos = v >> GAMMA_TO_LINEAR_BITS;
// fractional part, in GAMMA_TO_LINEAR_BITS fixed-point precision
const uint32_t x = v - (tab_pos << GAMMA_TO_LINEAR_BITS); // fractional part
// v0 / v1 are in GAMMA_TO_LINEAR_BITS fixed-point precision (range [0..1])
const uint32_t v0 = kLinearToGammaTabS[tab_pos + 0];
const uint32_t v1 = kLinearToGammaTabS[tab_pos + 1];
// Final interpolation. Note that rounding is already included.
const uint32_t v2 = (v1 - v0) * x; // note: v1 >= v0.
const uint32_t result = v0 + (v2 >> GAMMA_TO_LINEAR_BITS);
return result;
}
#else
static void InitGammaTablesS(void) {}
static WEBP_INLINE uint32_t GammaToLinearS(int v) {
return (v << GAMMA_TO_LINEAR_BITS) / MAX_Y_T;
}
static WEBP_INLINE uint32_t LinearToGammaS(uint32_t value) {
return (MAX_Y_T * value) >> GAMMA_TO_LINEAR_BITS;
}
#endif // USE_GAMMA_COMPRESSION
//------------------------------------------------------------------------------
static uint8_t clip_8b(fixed_t v) {
return (!(v & ~0xff)) ? (uint8_t)v : (v < 0) ? 0u : 255u;
}
static fixed_y_t clip_y(int y) {
return (!(y & ~MAX_Y_T)) ? (fixed_y_t)y : (y < 0) ? 0 : MAX_Y_T;
}
//------------------------------------------------------------------------------
static int RGBToGray(int r, int g, int b) {
const int luma = 13933 * r + 46871 * g + 4732 * b + YUV_HALF;
return (luma >> YUV_FIX);
}
static uint32_t ScaleDown(int a, int b, int c, int d) {
const uint32_t A = GammaToLinearS(a);
const uint32_t B = GammaToLinearS(b);
const uint32_t C = GammaToLinearS(c);
const uint32_t D = GammaToLinearS(d);
return LinearToGammaS((A + B + C + D + 2) >> 2);
}
static WEBP_INLINE void UpdateW(const fixed_y_t* src, fixed_y_t* dst, int w) {
int i;
for (i = 0; i < w; ++i) {
const uint32_t R = GammaToLinearS(src[0 * w + i]);
const uint32_t G = GammaToLinearS(src[1 * w + i]);
const uint32_t B = GammaToLinearS(src[2 * w + i]);
const uint32_t Y = RGBToGray(R, G, B);
dst[i] = (fixed_y_t)LinearToGammaS(Y);
}
}
static void UpdateChroma(const fixed_y_t* src1, const fixed_y_t* src2,
fixed_t* dst, int uv_w) {
int i;
for (i = 0; i < uv_w; ++i) {
const int r = ScaleDown(src1[0 * uv_w + 0], src1[0 * uv_w + 1],
src2[0 * uv_w + 0], src2[0 * uv_w + 1]);
const int g = ScaleDown(src1[2 * uv_w + 0], src1[2 * uv_w + 1],
src2[2 * uv_w + 0], src2[2 * uv_w + 1]);
const int b = ScaleDown(src1[4 * uv_w + 0], src1[4 * uv_w + 1],
src2[4 * uv_w + 0], src2[4 * uv_w + 1]);
const int W = RGBToGray(r, g, b);
dst[0 * uv_w] = (fixed_t)(r - W);
dst[1 * uv_w] = (fixed_t)(g - W);
dst[2 * uv_w] = (fixed_t)(b - W);
dst += 1;
src1 += 2;
src2 += 2;
}
}
static void StoreGray(const fixed_y_t* rgb, fixed_y_t* y, int w) {
int i;
for (i = 0; i < w; ++i) {
y[i] = RGBToGray(rgb[0 * w + i], rgb[1 * w + i], rgb[2 * w + i]);
}
}
//------------------------------------------------------------------------------
static WEBP_INLINE fixed_y_t Filter2(int A, int B, int W0) {
const int v0 = (A * 3 + B + 2) >> 2;
return clip_y(v0 + W0);
}
//------------------------------------------------------------------------------
static WEBP_INLINE fixed_y_t UpLift(uint8_t a) { // 8bit -> SFIX
return ((fixed_y_t)a << SFIX) | SHALF;
}
static void ImportOneRow(const uint8_t* const r_ptr,
const uint8_t* const g_ptr,
const uint8_t* const b_ptr,
int step,
int pic_width,
fixed_y_t* const dst) {
int i;
const int w = (pic_width + 1) & ~1;
for (i = 0; i < pic_width; ++i) {
const int off = i * step;
dst[i + 0 * w] = UpLift(r_ptr[off]);
dst[i + 1 * w] = UpLift(g_ptr[off]);
dst[i + 2 * w] = UpLift(b_ptr[off]);
}
if (pic_width & 1) { // replicate rightmost pixel
dst[pic_width + 0 * w] = dst[pic_width + 0 * w - 1];
dst[pic_width + 1 * w] = dst[pic_width + 1 * w - 1];
dst[pic_width + 2 * w] = dst[pic_width + 2 * w - 1];
}
}
static void InterpolateTwoRows(const fixed_y_t* const best_y,
const fixed_t* prev_uv,
const fixed_t* cur_uv,
const fixed_t* next_uv,
int w,
fixed_y_t* out1,
fixed_y_t* out2) {
const int uv_w = w >> 1;
const int len = (w - 1) >> 1; // length to filter
int k = 3;
while (k-- > 0) { // process each R/G/B segments in turn
// special boundary case for i==0
out1[0] = Filter2(cur_uv[0], prev_uv[0], best_y[0]);
out2[0] = Filter2(cur_uv[0], next_uv[0], best_y[w]);
WebPSharpYUVFilterRow(cur_uv, prev_uv, len, best_y + 0 + 1, out1 + 1);
WebPSharpYUVFilterRow(cur_uv, next_uv, len, best_y + w + 1, out2 + 1);
// special boundary case for i == w - 1 when w is even
if (!(w & 1)) {
out1[w - 1] = Filter2(cur_uv[uv_w - 1], prev_uv[uv_w - 1],
best_y[w - 1 + 0]);
out2[w - 1] = Filter2(cur_uv[uv_w - 1], next_uv[uv_w - 1],
best_y[w - 1 + w]);
}
out1 += w;
out2 += w;
prev_uv += uv_w;
cur_uv += uv_w;
next_uv += uv_w;
}
}
static WEBP_INLINE uint8_t ConvertRGBToY(int r, int g, int b) {
const int luma = 16839 * r + 33059 * g + 6420 * b + SROUNDER;
return clip_8b(16 + (luma >> (YUV_FIX + SFIX)));
}
static WEBP_INLINE uint8_t ConvertRGBToU(int r, int g, int b) {
const int u = -9719 * r - 19081 * g + 28800 * b + SROUNDER;
return clip_8b(128 + (u >> (YUV_FIX + SFIX)));
}
static WEBP_INLINE uint8_t ConvertRGBToV(int r, int g, int b) {
const int v = +28800 * r - 24116 * g - 4684 * b + SROUNDER;
return clip_8b(128 + (v >> (YUV_FIX + SFIX)));
}
static int ConvertWRGBToYUV(const fixed_y_t* best_y, const fixed_t* best_uv,
WebPPicture* const picture) {
int i, j;
uint8_t* dst_y = picture->y;
uint8_t* dst_u = picture->u;
uint8_t* dst_v = picture->v;
const fixed_t* const best_uv_base = best_uv;
const int w = (picture->width + 1) & ~1;
const int h = (picture->height + 1) & ~1;
const int uv_w = w >> 1;
const int uv_h = h >> 1;
for (best_uv = best_uv_base, j = 0; j < picture->height; ++j) {
for (i = 0; i < picture->width; ++i) {
const int off = (i >> 1);
const int W = best_y[i];
const int r = best_uv[off + 0 * uv_w] + W;
const int g = best_uv[off + 1 * uv_w] + W;
const int b = best_uv[off + 2 * uv_w] + W;
dst_y[i] = ConvertRGBToY(r, g, b);
}
best_y += w;
best_uv += (j & 1) * 3 * uv_w;
dst_y += picture->y_stride;
}
for (best_uv = best_uv_base, j = 0; j < uv_h; ++j) {
for (i = 0; i < uv_w; ++i) {
const int off = i;
const int r = best_uv[off + 0 * uv_w];
const int g = best_uv[off + 1 * uv_w];
const int b = best_uv[off + 2 * uv_w];
dst_u[i] = ConvertRGBToU(r, g, b);
dst_v[i] = ConvertRGBToV(r, g, b);
}
best_uv += 3 * uv_w;
dst_u += picture->uv_stride;
dst_v += picture->uv_stride;
}
return 1;
}
//------------------------------------------------------------------------------
// Main function
#define SAFE_ALLOC(W, H, T) ((T*)WebPSafeMalloc((W) * (H), sizeof(T)))
static int PreprocessARGB(const uint8_t* r_ptr,
const uint8_t* g_ptr,
const uint8_t* b_ptr,
int step, int rgb_stride,
WebPPicture* const picture) {
// we expand the right/bottom border if needed
const int w = (picture->width + 1) & ~1;
const int h = (picture->height + 1) & ~1;
const int uv_w = w >> 1;
const int uv_h = h >> 1;
uint64_t prev_diff_y_sum = ~0;
int j, iter;
// TODO(skal): allocate one big memory chunk. But for now, it's easier
// for valgrind debugging to have several chunks.
fixed_y_t* const tmp_buffer = SAFE_ALLOC(w * 3, 2, fixed_y_t); // scratch
fixed_y_t* const best_y_base = SAFE_ALLOC(w, h, fixed_y_t);
fixed_y_t* const target_y_base = SAFE_ALLOC(w, h, fixed_y_t);
fixed_y_t* const best_rgb_y = SAFE_ALLOC(w, 2, fixed_y_t);
fixed_t* const best_uv_base = SAFE_ALLOC(uv_w * 3, uv_h, fixed_t);
fixed_t* const target_uv_base = SAFE_ALLOC(uv_w * 3, uv_h, fixed_t);
fixed_t* const best_rgb_uv = SAFE_ALLOC(uv_w * 3, 1, fixed_t);
fixed_y_t* best_y = best_y_base;
fixed_y_t* target_y = target_y_base;
fixed_t* best_uv = best_uv_base;
fixed_t* target_uv = target_uv_base;
const uint64_t diff_y_threshold = (uint64_t)(3.0 * w * h);
int ok;
if (best_y_base == NULL || best_uv_base == NULL ||
target_y_base == NULL || target_uv_base == NULL ||
best_rgb_y == NULL || best_rgb_uv == NULL ||
tmp_buffer == NULL) {
ok = WebPEncodingSetError(picture, VP8_ENC_ERROR_OUT_OF_MEMORY);
goto End;
}
assert(picture->width >= kMinDimensionIterativeConversion);
assert(picture->height >= kMinDimensionIterativeConversion);
WebPInitConvertARGBToYUV();
// Import RGB samples to W/RGB representation.
for (j = 0; j < picture->height; j += 2) {
const int is_last_row = (j == picture->height - 1);
fixed_y_t* const src1 = tmp_buffer + 0 * w;
fixed_y_t* const src2 = tmp_buffer + 3 * w;
// prepare two rows of input
ImportOneRow(r_ptr, g_ptr, b_ptr, step, picture->width, src1);
if (!is_last_row) {
ImportOneRow(r_ptr + rgb_stride, g_ptr + rgb_stride, b_ptr + rgb_stride,
step, picture->width, src2);
} else {
memcpy(src2, src1, 3 * w * sizeof(*src2));
}
StoreGray(src1, best_y + 0, w);
StoreGray(src2, best_y + w, w);
UpdateW(src1, target_y, w);
UpdateW(src2, target_y + w, w);
UpdateChroma(src1, src2, target_uv, uv_w);
memcpy(best_uv, target_uv, 3 * uv_w * sizeof(*best_uv));
best_y += 2 * w;
best_uv += 3 * uv_w;
target_y += 2 * w;
target_uv += 3 * uv_w;
r_ptr += 2 * rgb_stride;
g_ptr += 2 * rgb_stride;
b_ptr += 2 * rgb_stride;
}
// Iterate and resolve clipping conflicts.
for (iter = 0; iter < kNumIterations; ++iter) {
const fixed_t* cur_uv = best_uv_base;
const fixed_t* prev_uv = best_uv_base;
uint64_t diff_y_sum = 0;
best_y = best_y_base;
best_uv = best_uv_base;
target_y = target_y_base;
target_uv = target_uv_base;
for (j = 0; j < h; j += 2) {
fixed_y_t* const src1 = tmp_buffer + 0 * w;
fixed_y_t* const src2 = tmp_buffer + 3 * w;
{
const fixed_t* const next_uv = cur_uv + ((j < h - 2) ? 3 * uv_w : 0);
InterpolateTwoRows(best_y, prev_uv, cur_uv, next_uv, w, src1, src2);
prev_uv = cur_uv;
cur_uv = next_uv;
}
UpdateW(src1, best_rgb_y + 0 * w, w);
UpdateW(src2, best_rgb_y + 1 * w, w);
UpdateChroma(src1, src2, best_rgb_uv, uv_w);
// update two rows of Y and one row of RGB
diff_y_sum += WebPSharpYUVUpdateY(target_y, best_rgb_y, best_y, 2 * w);
WebPSharpYUVUpdateRGB(target_uv, best_rgb_uv, best_uv, 3 * uv_w);
best_y += 2 * w;
best_uv += 3 * uv_w;
target_y += 2 * w;
target_uv += 3 * uv_w;
}
// test exit condition
if (iter > 0) {
if (diff_y_sum < diff_y_threshold) break;
if (diff_y_sum > prev_diff_y_sum) break;
}
prev_diff_y_sum = diff_y_sum;
}
// final reconstruction
ok = ConvertWRGBToYUV(best_y_base, best_uv_base, picture);
End:
WebPSafeFree(best_y_base);
WebPSafeFree(best_uv_base);
WebPSafeFree(target_y_base);
WebPSafeFree(target_uv_base);
WebPSafeFree(best_rgb_y);
WebPSafeFree(best_rgb_uv);
WebPSafeFree(tmp_buffer);
return ok;
}
#undef SAFE_ALLOC
//------------------------------------------------------------------------------
// "Fast" regular RGB->YUV
#define SUM4(ptr, step) LinearToGamma( \
GammaToLinear((ptr)[0]) + \
GammaToLinear((ptr)[(step)]) + \
GammaToLinear((ptr)[rgb_stride]) + \
GammaToLinear((ptr)[rgb_stride + (step)]), 0) \
#define SUM2(ptr) \
LinearToGamma(GammaToLinear((ptr)[0]) + GammaToLinear((ptr)[rgb_stride]), 1)
#define SUM2ALPHA(ptr) ((ptr)[0] + (ptr)[rgb_stride])
#define SUM4ALPHA(ptr) (SUM2ALPHA(ptr) + SUM2ALPHA((ptr) + 4))
#if defined(USE_INVERSE_ALPHA_TABLE)
static const int kAlphaFix = 19;
// Following table is (1 << kAlphaFix) / a. The (v * kInvAlpha[a]) >> kAlphaFix
// formula is then equal to v / a in most (99.6%) cases. Note that this table
// and constant are adjusted very tightly to fit 32b arithmetic.
// In particular, they use the fact that the operands for 'v / a' are actually
// derived as v = (a0.p0 + a1.p1 + a2.p2 + a3.p3) and a = a0 + a1 + a2 + a3
// with ai in [0..255] and pi in [0..1<<kGammaFix). The constraint to avoid
// overflow is: kGammaFix + kAlphaFix <= 31.
static const uint32_t kInvAlpha[4 * 0xff + 1] = {
0, /* alpha = 0 */
524288, 262144, 174762, 131072, 104857, 87381, 74898, 65536,
58254, 52428, 47662, 43690, 40329, 37449, 34952, 32768,
30840, 29127, 27594, 26214, 24966, 23831, 22795, 21845,
20971, 20164, 19418, 18724, 18078, 17476, 16912, 16384,
15887, 15420, 14979, 14563, 14169, 13797, 13443, 13107,
12787, 12483, 12192, 11915, 11650, 11397, 11155, 10922,
10699, 10485, 10280, 10082, 9892, 9709, 9532, 9362,
9198, 9039, 8886, 8738, 8594, 8456, 8322, 8192,
8065, 7943, 7825, 7710, 7598, 7489, 7384, 7281,
7182, 7084, 6990, 6898, 6808, 6721, 6636, 6553,
6472, 6393, 6316, 6241, 6168, 6096, 6026, 5957,
5890, 5825, 5761, 5698, 5637, 5577, 5518, 5461,
5405, 5349, 5295, 5242, 5190, 5140, 5090, 5041,
4993, 4946, 4899, 4854, 4809, 4766, 4723, 4681,
4639, 4599, 4559, 4519, 4481, 4443, 4405, 4369,
4332, 4297, 4262, 4228, 4194, 4161, 4128, 4096,
4064, 4032, 4002, 3971, 3942, 3912, 3883, 3855,
3826, 3799, 3771, 3744, 3718, 3692, 3666, 3640,
3615, 3591, 3566, 3542, 3518, 3495, 3472, 3449,
3426, 3404, 3382, 3360, 3339, 3318, 3297, 3276,
3256, 3236, 3216, 3196, 3177, 3158, 3139, 3120,
3102, 3084, 3066, 3048, 3030, 3013, 2995, 2978,
2962, 2945, 2928, 2912, 2896, 2880, 2864, 2849,
2833, 2818, 2803, 2788, 2774, 2759, 2744, 2730,
2716, 2702, 2688, 2674, 2661, 2647, 2634, 2621,
2608, 2595, 2582, 2570, 2557, 2545, 2532, 2520,
2508, 2496, 2484, 2473, 2461, 2449, 2438, 2427,
2416, 2404, 2394, 2383, 2372, 2361, 2351, 2340,
2330, 2319, 2309, 2299, 2289, 2279, 2269, 2259,
2250, 2240, 2231, 2221, 2212, 2202, 2193, 2184,
2175, 2166, 2157, 2148, 2139, 2131, 2122, 2114,
2105, 2097, 2088, 2080, 2072, 2064, 2056, 2048,
2040, 2032, 2024, 2016, 2008, 2001, 1993, 1985,
1978, 1971, 1963, 1956, 1949, 1941, 1934, 1927,
1920, 1913, 1906, 1899, 1892, 1885, 1879, 1872,
1865, 1859, 1852, 1846, 1839, 1833, 1826, 1820,
1814, 1807, 1801, 1795, 1789, 1783, 1777, 1771,
1765, 1759, 1753, 1747, 1741, 1736, 1730, 1724,
1718, 1713, 1707, 1702, 1696, 1691, 1685, 1680,
1675, 1669, 1664, 1659, 1653, 1648, 1643, 1638,
1633, 1628, 1623, 1618, 1613, 1608, 1603, 1598,
1593, 1588, 1583, 1579, 1574, 1569, 1565, 1560,
1555, 1551, 1546, 1542, 1537, 1533, 1528, 1524,
1519, 1515, 1510, 1506, 1502, 1497, 1493, 1489,
1485, 1481, 1476, 1472, 1468, 1464, 1460, 1456,
1452, 1448, 1444, 1440, 1436, 1432, 1428, 1424,
1420, 1416, 1413, 1409, 1405, 1401, 1398, 1394,
1390, 1387, 1383, 1379, 1376, 1372, 1368, 1365,
1361, 1358, 1354, 1351, 1347, 1344, 1340, 1337,
1334, 1330, 1327, 1323, 1320, 1317, 1314, 1310,
1307, 1304, 1300, 1297, 1294, 1291, 1288, 1285,
1281, 1278, 1275, 1272, 1269, 1266, 1263, 1260,
1257, 1254, 1251, 1248, 1245, 1242, 1239, 1236,
1233, 1230, 1227, 1224, 1222, 1219, 1216, 1213,
1210, 1208, 1205, 1202, 1199, 1197, 1194, 1191,
1188, 1186, 1183, 1180, 1178, 1175, 1172, 1170,
1167, 1165, 1162, 1159, 1157, 1154, 1152, 1149,
1147, 1144, 1142, 1139, 1137, 1134, 1132, 1129,
1127, 1125, 1122, 1120, 1117, 1115, 1113, 1110,
1108, 1106, 1103, 1101, 1099, 1096, 1094, 1092,
1089, 1087, 1085, 1083, 1081, 1078, 1076, 1074,
1072, 1069, 1067, 1065, 1063, 1061, 1059, 1057,
1054, 1052, 1050, 1048, 1046, 1044, 1042, 1040,
1038, 1036, 1034, 1032, 1030, 1028, 1026, 1024,
1022, 1020, 1018, 1016, 1014, 1012, 1010, 1008,
1006, 1004, 1002, 1000, 998, 996, 994, 992,
991, 989, 987, 985, 983, 981, 979, 978,
976, 974, 972, 970, 969, 967, 965, 963,
961, 960, 958, 956, 954, 953, 951, 949,
948, 946, 944, 942, 941, 939, 937, 936,
934, 932, 931, 929, 927, 926, 924, 923,
921, 919, 918, 916, 914, 913, 911, 910,
908, 907, 905, 903, 902, 900, 899, 897,
896, 894, 893, 891, 890, 888, 887, 885,
884, 882, 881, 879, 878, 876, 875, 873,
872, 870, 869, 868, 866, 865, 863, 862,
860, 859, 858, 856, 855, 853, 852, 851,
849, 848, 846, 845, 844, 842, 841, 840,
838, 837, 836, 834, 833, 832, 830, 829,
828, 826, 825, 824, 823, 821, 820, 819,
817, 816, 815, 814, 812, 811, 810, 809,
807, 806, 805, 804, 802, 801, 800, 799,
798, 796, 795, 794, 793, 791, 790, 789,
788, 787, 786, 784, 783, 782, 781, 780,
779, 777, 776, 775, 774, 773, 772, 771,
769, 768, 767, 766, 765, 764, 763, 762,
760, 759, 758, 757, 756, 755, 754, 753,
752, 751, 750, 748, 747, 746, 745, 744,
743, 742, 741, 740, 739, 738, 737, 736,
735, 734, 733, 732, 731, 730, 729, 728,
727, 726, 725, 724, 723, 722, 721, 720,
719, 718, 717, 716, 715, 714, 713, 712,
711, 710, 709, 708, 707, 706, 705, 704,
703, 702, 701, 700, 699, 699, 698, 697,
696, 695, 694, 693, 692, 691, 690, 689,
688, 688, 687, 686, 685, 684, 683, 682,
681, 680, 680, 679, 678, 677, 676, 675,
674, 673, 673, 672, 671, 670, 669, 668,
667, 667, 666, 665, 664, 663, 662, 661,
661, 660, 659, 658, 657, 657, 656, 655,
654, 653, 652, 652, 651, 650, 649, 648,
648, 647, 646, 645, 644, 644, 643, 642,
641, 640, 640, 639, 638, 637, 637, 636,
635, 634, 633, 633, 632, 631, 630, 630,
629, 628, 627, 627, 626, 625, 624, 624,
623, 622, 621, 621, 620, 619, 618, 618,
617, 616, 616, 615, 614, 613, 613, 612,
611, 611, 610, 609, 608, 608, 607, 606,
606, 605, 604, 604, 603, 602, 601, 601,
600, 599, 599, 598, 597, 597, 596, 595,
595, 594, 593, 593, 592, 591, 591, 590,
589, 589, 588, 587, 587, 586, 585, 585,
584, 583, 583, 582, 581, 581, 580, 579,
579, 578, 578, 577, 576, 576, 575, 574,
574, 573, 572, 572, 571, 571, 570, 569,
569, 568, 568, 567, 566, 566, 565, 564,
564, 563, 563, 562, 561, 561, 560, 560,
559, 558, 558, 557, 557, 556, 555, 555,
554, 554, 553, 553, 552, 551, 551, 550,
550, 549, 548, 548, 547, 547, 546, 546,
545, 544, 544, 543, 543, 542, 542, 541,
541, 540, 539, 539, 538, 538, 537, 537,
536, 536, 535, 534, 534, 533, 533, 532,
532, 531, 531, 530, 530, 529, 529, 528,
527, 527, 526, 526, 525, 525, 524, 524,
523, 523, 522, 522, 521, 521, 520, 520,
519, 519, 518, 518, 517, 517, 516, 516,
515, 515, 514, 514
};
// Note that LinearToGamma() expects the values to be premultiplied by 4,
// so we incorporate this factor 4 inside the DIVIDE_BY_ALPHA macro directly.
#define DIVIDE_BY_ALPHA(sum, a) (((sum) * kInvAlpha[(a)]) >> (kAlphaFix - 2))
#else
#define DIVIDE_BY_ALPHA(sum, a) (4 * (sum) / (a))
#endif // USE_INVERSE_ALPHA_TABLE
static WEBP_INLINE int LinearToGammaWeighted(const uint8_t* src,
const uint8_t* a_ptr,
uint32_t total_a, int step,
int rgb_stride) {
const uint32_t sum =
a_ptr[0] * GammaToLinear(src[0]) +
a_ptr[step] * GammaToLinear(src[step]) +
a_ptr[rgb_stride] * GammaToLinear(src[rgb_stride]) +
a_ptr[rgb_stride + step] * GammaToLinear(src[rgb_stride + step]);
assert(total_a > 0 && total_a <= 4 * 0xff);
#if defined(USE_INVERSE_ALPHA_TABLE)
assert((uint64_t)sum * kInvAlpha[total_a] < ((uint64_t)1 << 32));
#endif
return LinearToGamma(DIVIDE_BY_ALPHA(sum, total_a), 0);
}
static WEBP_INLINE void ConvertRowToY(const uint8_t* const r_ptr,
const uint8_t* const g_ptr,
const uint8_t* const b_ptr,
int step,
uint8_t* const dst_y,
int width,
VP8Random* const rg) {
int i, j;
for (i = 0, j = 0; i < width; i += 1, j += step) {
dst_y[i] = RGBToY(r_ptr[j], g_ptr[j], b_ptr[j], rg);
}
}
static WEBP_INLINE void AccumulateRGBA(const uint8_t* const r_ptr,
const uint8_t* const g_ptr,
const uint8_t* const b_ptr,
const uint8_t* const a_ptr,
int rgb_stride,
uint16_t* dst, int width) {
int i, j;
// we loop over 2x2 blocks and produce one R/G/B/A value for each.
for (i = 0, j = 0; i < (width >> 1); i += 1, j += 2 * 4, dst += 4) {
const uint32_t a = SUM4ALPHA(a_ptr + j);
int r, g, b;
if (a == 4 * 0xff || a == 0) {
r = SUM4(r_ptr + j, 4);
g = SUM4(g_ptr + j, 4);
b = SUM4(b_ptr + j, 4);
} else {
r = LinearToGammaWeighted(r_ptr + j, a_ptr + j, a, 4, rgb_stride);
g = LinearToGammaWeighted(g_ptr + j, a_ptr + j, a, 4, rgb_stride);
b = LinearToGammaWeighted(b_ptr + j, a_ptr + j, a, 4, rgb_stride);
}
dst[0] = r;
dst[1] = g;
dst[2] = b;
dst[3] = a;
}
if (width & 1) {
const uint32_t a = 2u * SUM2ALPHA(a_ptr + j);
int r, g, b;
if (a == 4 * 0xff || a == 0) {
r = SUM2(r_ptr + j);
g = SUM2(g_ptr + j);
b = SUM2(b_ptr + j);
} else {
r = LinearToGammaWeighted(r_ptr + j, a_ptr + j, a, 0, rgb_stride);
g = LinearToGammaWeighted(g_ptr + j, a_ptr + j, a, 0, rgb_stride);
b = LinearToGammaWeighted(b_ptr + j, a_ptr + j, a, 0, rgb_stride);
}
dst[0] = r;
dst[1] = g;
dst[2] = b;
dst[3] = a;
}
}
static WEBP_INLINE void AccumulateRGB(const uint8_t* const r_ptr,
const uint8_t* const g_ptr,
const uint8_t* const b_ptr,
int step, int rgb_stride,
uint16_t* dst, int width) {
int i, j;
for (i = 0, j = 0; i < (width >> 1); i += 1, j += 2 * step, dst += 4) {
dst[0] = SUM4(r_ptr + j, step);
dst[1] = SUM4(g_ptr + j, step);
dst[2] = SUM4(b_ptr + j, step);
}
if (width & 1) {
dst[0] = SUM2(r_ptr + j);
dst[1] = SUM2(g_ptr + j);
dst[2] = SUM2(b_ptr + j);
}
}
static WEBP_INLINE void ConvertRowsToUV(const uint16_t* rgb,
uint8_t* const dst_u,
uint8_t* const dst_v,
int width,
VP8Random* const rg) {
int i;
for (i = 0; i < width; i += 1, rgb += 4) {
const int r = rgb[0], g = rgb[1], b = rgb[2];
dst_u[i] = RGBToU(r, g, b, rg);
dst_v[i] = RGBToV(r, g, b, rg);
}
}
static int ImportYUVAFromRGBA(const uint8_t* r_ptr,
const uint8_t* g_ptr,
const uint8_t* b_ptr,
const uint8_t* a_ptr,
int step, // bytes per pixel
int rgb_stride, // bytes per scanline
float dithering,
int use_iterative_conversion,
WebPPicture* const picture) {
int y;
const int width = picture->width;
const int height = picture->height;
const int has_alpha = CheckNonOpaque(a_ptr, width, height, step, rgb_stride);
const int is_rgb = (r_ptr < b_ptr); // otherwise it's bgr
picture->colorspace = has_alpha ? WEBP_YUV420A : WEBP_YUV420;
picture->use_argb = 0;
// disable smart conversion if source is too small (overkill).
if (width < kMinDimensionIterativeConversion ||
height < kMinDimensionIterativeConversion) {
use_iterative_conversion = 0;
}
if (!WebPPictureAllocYUVA(picture, width, height)) {
return 0;
}
if (has_alpha) {
assert(step == 4);
#if defined(USE_GAMMA_COMPRESSION) && defined(USE_INVERSE_ALPHA_TABLE)
assert(kAlphaFix + kGammaFix <= 31);
#endif
}
if (use_iterative_conversion) {
InitGammaTablesS();
if (!PreprocessARGB(r_ptr, g_ptr, b_ptr, step, rgb_stride, picture)) {
return 0;
}
if (has_alpha) {
WebPExtractAlpha(a_ptr, rgb_stride, width, height,
picture->a, picture->a_stride);
}
} else {
const int uv_width = (width + 1) >> 1;
int use_dsp = (step == 3); // use special function in this case
// temporary storage for accumulated R/G/B values during conversion to U/V
uint16_t* const tmp_rgb =
(uint16_t*)WebPSafeMalloc(4 * uv_width, sizeof(*tmp_rgb));
uint8_t* dst_y = picture->y;
uint8_t* dst_u = picture->u;
uint8_t* dst_v = picture->v;
uint8_t* dst_a = picture->a;
VP8Random base_rg;
VP8Random* rg = NULL;
if (dithering > 0.) {
VP8InitRandom(&base_rg, dithering);
rg = &base_rg;
use_dsp = 0; // can't use dsp in this case
}
WebPInitConvertARGBToYUV();
InitGammaTables();
if (tmp_rgb == NULL) return 0; // malloc error
// Downsample Y/U/V planes, two rows at a time
for (y = 0; y < (height >> 1); ++y) {
int rows_have_alpha = has_alpha;
if (use_dsp) {
if (is_rgb) {
WebPConvertRGB24ToY(r_ptr, dst_y, width);
WebPConvertRGB24ToY(r_ptr + rgb_stride,
dst_y + picture->y_stride, width);
} else {
WebPConvertBGR24ToY(b_ptr, dst_y, width);
WebPConvertBGR24ToY(b_ptr + rgb_stride,
dst_y + picture->y_stride, width);
}
} else {
ConvertRowToY(r_ptr, g_ptr, b_ptr, step, dst_y, width, rg);
ConvertRowToY(r_ptr + rgb_stride,
g_ptr + rgb_stride,
b_ptr + rgb_stride, step,
dst_y + picture->y_stride, width, rg);
}
dst_y += 2 * picture->y_stride;
if (has_alpha) {
rows_have_alpha &= !WebPExtractAlpha(a_ptr, rgb_stride, width, 2,
dst_a, picture->a_stride);
dst_a += 2 * picture->a_stride;
}
// Collect averaged R/G/B(/A)
if (!rows_have_alpha) {
AccumulateRGB(r_ptr, g_ptr, b_ptr, step, rgb_stride, tmp_rgb, width);
} else {
AccumulateRGBA(r_ptr, g_ptr, b_ptr, a_ptr, rgb_stride, tmp_rgb, width);
}
// Convert to U/V
if (rg == NULL) {
WebPConvertRGBA32ToUV(tmp_rgb, dst_u, dst_v, uv_width);
} else {
ConvertRowsToUV(tmp_rgb, dst_u, dst_v, uv_width, rg);
}
dst_u += picture->uv_stride;
dst_v += picture->uv_stride;
r_ptr += 2 * rgb_stride;
b_ptr += 2 * rgb_stride;
g_ptr += 2 * rgb_stride;
if (has_alpha) a_ptr += 2 * rgb_stride;
}
if (height & 1) { // extra last row
int row_has_alpha = has_alpha;
if (use_dsp) {
if (r_ptr < b_ptr) {
WebPConvertRGB24ToY(r_ptr, dst_y, width);
} else {
WebPConvertBGR24ToY(b_ptr, dst_y, width);
}
} else {
ConvertRowToY(r_ptr, g_ptr, b_ptr, step, dst_y, width, rg);
}
if (row_has_alpha) {
row_has_alpha &= !WebPExtractAlpha(a_ptr, 0, width, 1, dst_a, 0);
}
// Collect averaged R/G/B(/A)
if (!row_has_alpha) {
// Collect averaged R/G/B
AccumulateRGB(r_ptr, g_ptr, b_ptr, step, /* rgb_stride = */ 0,
tmp_rgb, width);
} else {
AccumulateRGBA(r_ptr, g_ptr, b_ptr, a_ptr, /* rgb_stride = */ 0,
tmp_rgb, width);
}
if (rg == NULL) {
WebPConvertRGBA32ToUV(tmp_rgb, dst_u, dst_v, uv_width);
} else {
ConvertRowsToUV(tmp_rgb, dst_u, dst_v, uv_width, rg);
}
}
WebPSafeFree(tmp_rgb);
}
return 1;
}
#undef SUM4
#undef SUM2
#undef SUM4ALPHA
#undef SUM2ALPHA
//------------------------------------------------------------------------------
// call for ARGB->YUVA conversion
static int PictureARGBToYUVA(WebPPicture* picture, WebPEncCSP colorspace,
float dithering, int use_iterative_conversion) {
if (picture == NULL) return 0;
if (picture->argb == NULL) {
return WebPEncodingSetError(picture, VP8_ENC_ERROR_NULL_PARAMETER);
} else if ((colorspace & WEBP_CSP_UV_MASK) != WEBP_YUV420) {
return WebPEncodingSetError(picture, VP8_ENC_ERROR_INVALID_CONFIGURATION);
} else {
const uint8_t* const argb = (const uint8_t*)picture->argb;
const uint8_t* const a = argb + (0 ^ ALPHA_OFFSET);
const uint8_t* const r = argb + (1 ^ ALPHA_OFFSET);
const uint8_t* const g = argb + (2 ^ ALPHA_OFFSET);
const uint8_t* const b = argb + (3 ^ ALPHA_OFFSET);
picture->colorspace = WEBP_YUV420;
return ImportYUVAFromRGBA(r, g, b, a, 4, 4 * picture->argb_stride,
dithering, use_iterative_conversion, picture);
}
}
int WebPPictureARGBToYUVADithered(WebPPicture* picture, WebPEncCSP colorspace,
float dithering) {
return PictureARGBToYUVA(picture, colorspace, dithering, 0);
}
int WebPPictureARGBToYUVA(WebPPicture* picture, WebPEncCSP colorspace) {
return PictureARGBToYUVA(picture, colorspace, 0.f, 0);
}
int WebPPictureSharpARGBToYUVA(WebPPicture* picture) {
return PictureARGBToYUVA(picture, WEBP_YUV420, 0.f, 1);
}
// for backward compatibility
int WebPPictureSmartARGBToYUVA(WebPPicture* picture) {
return WebPPictureSharpARGBToYUVA(picture);
}
//------------------------------------------------------------------------------
// call for YUVA -> ARGB conversion
int WebPPictureYUVAToARGB(WebPPicture* picture) {
if (picture == NULL) return 0;
if (picture->y == NULL || picture->u == NULL || picture->v == NULL) {
return WebPEncodingSetError(picture, VP8_ENC_ERROR_NULL_PARAMETER);
}
if ((picture->colorspace & WEBP_CSP_ALPHA_BIT) && picture->a == NULL) {
return WebPEncodingSetError(picture, VP8_ENC_ERROR_NULL_PARAMETER);
}
if ((picture->colorspace & WEBP_CSP_UV_MASK) != WEBP_YUV420) {
return WebPEncodingSetError(picture, VP8_ENC_ERROR_INVALID_CONFIGURATION);
}
// Allocate a new argb buffer (discarding the previous one).
if (!WebPPictureAllocARGB(picture, picture->width, picture->height)) return 0;
picture->use_argb = 1;
// Convert
{
int y;
const int width = picture->width;
const int height = picture->height;
const int argb_stride = 4 * picture->argb_stride;
uint8_t* dst = (uint8_t*)picture->argb;
const uint8_t *cur_u = picture->u, *cur_v = picture->v, *cur_y = picture->y;
WebPUpsampleLinePairFunc upsample =
WebPGetLinePairConverter(ALPHA_OFFSET > 0);
// First row, with replicated top samples.
upsample(cur_y, NULL, cur_u, cur_v, cur_u, cur_v, dst, NULL, width);
cur_y += picture->y_stride;
dst += argb_stride;
// Center rows.
for (y = 1; y + 1 < height; y += 2) {
const uint8_t* const top_u = cur_u;
const uint8_t* const top_v = cur_v;
cur_u += picture->uv_stride;
cur_v += picture->uv_stride;
upsample(cur_y, cur_y + picture->y_stride, top_u, top_v, cur_u, cur_v,
dst, dst + argb_stride, width);
cur_y += 2 * picture->y_stride;
dst += 2 * argb_stride;
}
// Last row (if needed), with replicated bottom samples.
if (height > 1 && !(height & 1)) {
upsample(cur_y, NULL, cur_u, cur_v, cur_u, cur_v, dst, NULL, width);
}
// Insert alpha values if needed, in replacement for the default 0xff ones.
if (picture->colorspace & WEBP_CSP_ALPHA_BIT) {
for (y = 0; y < height; ++y) {
uint32_t* const argb_dst = picture->argb + y * picture->argb_stride;
const uint8_t* const src = picture->a + y * picture->a_stride;
int x;
for (x = 0; x < width; ++x) {
argb_dst[x] = (argb_dst[x] & 0x00ffffffu) | ((uint32_t)src[x] << 24);
}
}
}
}
return 1;
}
//------------------------------------------------------------------------------
// automatic import / conversion
static int Import(WebPPicture* const picture,
const uint8_t* rgb, int rgb_stride,
int step, int swap_rb, int import_alpha) {
int y;
// swap_rb -> b,g,r,a , !swap_rb -> r,g,b,a
const uint8_t* r_ptr = rgb + (swap_rb ? 2 : 0);
const uint8_t* g_ptr = rgb + 1;
const uint8_t* b_ptr = rgb + (swap_rb ? 0 : 2);
const int width = picture->width;
const int height = picture->height;
if (!picture->use_argb) {
const uint8_t* a_ptr = import_alpha ? rgb + 3 : NULL;
return ImportYUVAFromRGBA(r_ptr, g_ptr, b_ptr, a_ptr, step, rgb_stride,
0.f /* no dithering */, 0, picture);
}
if (!WebPPictureAlloc(picture)) return 0;
VP8LDspInit();
WebPInitAlphaProcessing();
if (import_alpha) {
// dst[] byte order is {a,r,g,b} for big-endian, {b,g,r,a} for little endian
uint32_t* dst = picture->argb;
const int do_copy = (ALPHA_OFFSET == 3) && swap_rb;
assert(step == 4);
if (do_copy) {
for (y = 0; y < height; ++y) {
memcpy(dst, rgb, width * 4);
rgb += rgb_stride;
dst += picture->argb_stride;
}
} else {
for (y = 0; y < height; ++y) {
#ifdef WORDS_BIGENDIAN
// BGRA or RGBA input order.
const uint8_t* a_ptr = rgb + 3;
WebPPackARGB(a_ptr, r_ptr, g_ptr, b_ptr, width, dst);
r_ptr += rgb_stride;
g_ptr += rgb_stride;
b_ptr += rgb_stride;
#else
// RGBA input order. Need to swap R and B.
VP8LConvertBGRAToRGBA((const uint32_t*)rgb, width, (uint8_t*)dst);
#endif
rgb += rgb_stride;
dst += picture->argb_stride;
}
}
} else {
uint32_t* dst = picture->argb;
assert(step >= 3);
for (y = 0; y < height; ++y) {
WebPPackRGB(r_ptr, g_ptr, b_ptr, width, step, dst);
r_ptr += rgb_stride;
g_ptr += rgb_stride;
b_ptr += rgb_stride;
dst += picture->argb_stride;
}
}
return 1;
}
// Public API
#if !defined(WEBP_REDUCE_CSP)
int WebPPictureImportBGR(WebPPicture* picture,
const uint8_t* rgb, int rgb_stride) {
return (picture != NULL && rgb != NULL)
? Import(picture, rgb, rgb_stride, 3, 1, 0)
: 0;
}
int WebPPictureImportBGRA(WebPPicture* picture,
const uint8_t* rgba, int rgba_stride) {
return (picture != NULL && rgba != NULL)
? Import(picture, rgba, rgba_stride, 4, 1, 1)
: 0;
}
int WebPPictureImportBGRX(WebPPicture* picture,
const uint8_t* rgba, int rgba_stride) {
return (picture != NULL && rgba != NULL)
? Import(picture, rgba, rgba_stride, 4, 1, 0)
: 0;
}
#endif // WEBP_REDUCE_CSP
int WebPPictureImportRGB(WebPPicture* picture,
const uint8_t* rgb, int rgb_stride) {
return (picture != NULL && rgb != NULL)
? Import(picture, rgb, rgb_stride, 3, 0, 0)
: 0;
}
int WebPPictureImportRGBA(WebPPicture* picture,
const uint8_t* rgba, int rgba_stride) {
return (picture != NULL && rgba != NULL)
? Import(picture, rgba, rgba_stride, 4, 0, 1)
: 0;
}
int WebPPictureImportRGBX(WebPPicture* picture,
const uint8_t* rgba, int rgba_stride) {
return (picture != NULL && rgba != NULL)
? Import(picture, rgba, rgba_stride, 4, 0, 0)
: 0;
}
//------------------------------------------------------------------------------
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